The border of the greatest distribution of glaciation on the map. Relief of areas of continental glaciation

The question of where the boundary of maximum glaciation should be drawn within the Ural Range and what was the role of the Urals as an independent center of glaciation in the Quaternary remains open to this day, despite the obvious importance that it has for solving the problem of synchronization of glaciations in the North Eastern part of the Russian plain and the West Siberian lowland.

Usually survey geological maps of the European and Asian parts of the Union show the boundary of maximum glaciation or the boundary of maximum distribution of erratic boulders.

In the western part of the USSR, in the region of the Dnieper and Don glacial tongues, this boundary has long been established and has not undergone significant changes.

The question of the maximum boundary of the distribution of glaciation to the east of the Kama River is in a completely different position, i.e. in the Urals and adjacent parts of the European Plain and the West Siberian Lowland.

It is enough to look at the attached map (Fig. 1), which shows the boundaries according to different authors, to see that there is no consistency on this issue.

So, for example, the maximum boundary of the distribution of erratic boulders on the map of the Quaternary deposits of the European part of the USSR and adjacent countries (on a scale of 1: 2,500,000, 1932, edited by S.A. Yakovlev) is shown in the Urals south of the Konzhakovsky stone, those. south of 60 ° N, and on the geological map of the European part of the USSR (on a scale of 1: 2,500,000, 1933, edited by A.M. Zhirmunsky), the boundary of the maximum distribution of glaciers is shown, and in the Urals it runs to the north from Mount Chistop, i.e. at 61°40"N

Thus, on two maps published by the same institution almost simultaneously, in the Urals the difference in drawing the same border, only called differently, reaches two degrees.

Another example of inconsistency in the issue of the maximum glaciation limit in the Urals can be seen in two works by G.F. Mirchinka, which were published at the same time - in 1937.

In the first case - on the map of Quaternary deposits, placed in the Great Soviet Atlas of the World, G.F. Mirchink shows the boundary of the distribution of boulders of the Rice time and draws it to the north of Mount Chistop, i.e. at 61°35"N

In another work - "The Quaternary period and its fauna" the authors [Gromov and Mirchink, 1937 ] draw the boundary of maximum glaciation, which is described in the text as Ris, only slightly north of the latitude of Sverdlovsk.

Thus, the border of the distribution of rice glaciation is shown here in the Urals 4 ½ degrees south of the border of the distribution of boulders of rice time!

From a review of the factual material underlying these constructions, it is easy to see that, due to the lack of data for the Urals proper, there was a wide interpolation between the extreme southern points of the location of glacial deposits in the adjacent parts of the lowlands. And so the border of glaciation in the mountains was drawn to a large extent arbitrarily, in the interval from 57 ° N.L. up to 62° N

It is also obvious that there were several ways of drawing this boundary. The first way was that the border was drawn in the latitudinal direction, ignoring the Urals as a major orographic unit. Although it is quite clear that orographic factors have always been and are of great importance for the distribution of glaciers and firn fields.

Other authors preferred to draw the boundary of the maximum ancient glaciation within the range, relying on those points for which there are indisputable traces of ancient glaciation. In this case, the boundary, contrary to the well-known principles of vertical climatic zonality (and now well-defined within the Urals), deviated significantly to the north (up to 62° N).

Such a boundary, although drawn in accordance with the actual data, involuntarily led to ideas about the presence of special physical and geographical conditions that existed along the edge of the glacier at the time of maximum glaciation. Moreover, these conditions obviously influenced such a peculiar distribution of the ice cover in the Urals and in the adjacent lowlands.

Meanwhile, the question here was decided solely by the absence of facts, and the boundary deviated to the north without any regard for the orography of the ridge.

Still others marked the boundary also at points for which there are indisputable traces of glaciation. However, they made a significant mistake, since the boundary was drawn on the basis of a number of facts concerning exceptionally fresh and very young glacial forms (cars, cirques) that arose in the Northern Urals in the post-Würmian time. (Proof of the latter is a whole series of observations of fresh Alpine forms of glaciation in the Subpolar Urals, Taimyr, etc.)

Therefore, it is not clear how it was possible to link the ancient boundary of maximum glaciation with these fresh forms of very young glaciation.

Finally, another solution to the problem has been proposed only very recently. It consists in drawing the border of glaciation within the mountains, to the south of the corresponding border in the adjacent parts of the lowlands, taking into account the significant height of the Ural Range, on which, at the time of the onset of the climatic minimum, local centers of glaciation should have naturally developed first of all. However, this boundary was drawn purely hypothetically, since there were no actual data on traces of glaciation within the ridge south of the latitude of the Konzhakovsky stone (see below).

From this, the interest that the study of Quaternary deposits and the geomorphology of the Ural segment, which lies directly to the south of the places where unconditional signs of glaciation were found (south of 61 ° 40 "N. latitude), is obvious. At the same time, already old works, in which there were detailed description of the relief of the Urals in the basins of Lozva, Sosva and Vishera [Fedorov, 1887; 1889; 1890; Fedorov and Nikitin, 1901; Duparc & Pearce, 1905a; 1905b; Duparc et al., 1909], showed that here one has to deal with a peculiar relief, characterized by an almost complete absence of glacial forms and a very wide development of upland terraces, in which only a few researchers [Aleshkov, 1935; Aleschkow, 1935] consider it possible to see traces of past glacial activity.

Thus, the question of drawing the boundary of glaciation within the mountains here is closely connected with the solution of the problem of upland terraces.

In their conclusions, the authors rely on the factual material obtained as a result of work in the basins pp. Vishera, Lozva and Sosva (in 1939) and during a number of previous years in the Subpolar Urals, in the Kama-Pechora region and in the West Siberian lowland (S.G. Boch, 1929-1938; I.I. Krasnov, 1934 -1938).

In particular, in 1939 the authors visited the following points within the Ural Range and the adjacent parts of the lowlands between 61°40"N and 58°30"N. immediately south of the boundary of the distribution of glacial boulders indicated by E.S. Fedorov [1890 ]: peaks and massifs of Mt. Chistop (1925 m); Oika-Chakur; Molebny Kamen (Yalping-ner, 1296 m); Isherim city (1331 m); Ant Stone (Khus-Oika peak, 1240 m); Martai (1131 m); Alder Stone; Tulymsky Stone (northern tip); Pu-Tump; Fifth Tump; Khoza-Tump; Belt Stone (peaks 1341 m and 1252 m); Quarkush; Denezhkin Stone (1496 m); Zhuravlev Stone (788 m); Kazansky Stone (1036 m); Kumba (929 m); Konzhakovsky Stone (1670 m); Kosvinsky Stone (1495 m); Sukhogorsky Stone (1167 m); Kachkanar (886 m); Bassegui (987 m). Valleys were also passed: r. Vishera (from the city of Krasnovishersk to the mouth of the B. Moiva river) and its left tributaries - B. Moiva, Velsa and Ulsa with a tributary of the Kutim; R. Lozva (from the village of Ivdel to the mouth of the Ushma river), the upper reaches of pp. Vizhaya, Toshemki, Vapsos, r. Kolokolnaya, Vagran (from the village of Petropavlovsk to the upper reaches and the river Kosya).

At the same time, some routes of L. Duparc and E.S. were partially repeated. Fedorov in order to verify and link observations.

* * *

Before proceeding to the description of the material and conclusions, we should dwell on a review of the literature, which contains factual data on the issues of glaciation of the Urals.

Evidence of glaciation in a mountainous area, as is well known, can serve, in addition to glacial deposits (moraines), which are far from preserved everywhere, also glacial landforms. First of all - trogs and punishments. Observations on glacial polishing and scarring could also be of significant importance. However, due to the energy of the processes of frosty weathering in the Northern Urals, they have not survived almost anywhere.

Starting the survey from the extreme northern parts of the ridge, located above 65 ° 30 "N, we are convinced that glacial deposits and landforms are extremely pronounced here (see descriptions: E. Hoffman [Hofmann, 1856]; O.O. Backlund [ 1911 ]; B.N. Gorodkova [1926a; 1926b; 1929]; A.I. Aleshkova [ 1935 ]; G.L. Padalki [ 1936 ]; A.I. Zavaritsky [1932 ]).

B.N. Gorodkov [1929 ], A.I. Aleshkov [1931; 1935; 1937 ], T.A. Dobrolyubova and E.S. Soshkina [1935 ], V.S. Govorukhin [1934 ], S.G. Bochem [ 1935 ] and N.A. Sirin [ 1939 ].

In the entire area mentioned above, the moraine usually occurs in negative relief forms, lining the bottoms of the troughs and forming hilly-morainic landscapes and chains of terminal moraines in the troughs and at the mouths of the kars. On the slopes of mountain ranges and flat surfaces of mountains, only single erratic boulders are usually found.

South of 64°N and up to 60° N, i.e. in that part of the Urals, which is now commonly called the Northern Urals, traces of glaciation fade as they move from north to south.

Finally, south of the latitude of Konzhakovsky Kamen, there is no information about glacial deposits and glacial landforms.

The transition from the area of ​​ubiquitous development of glacial deposits to the area where they are absent is apparently not so gradual and is undoubtedly associated with the passage of the boundary of repeated glaciation in this area (Wurm - in the terminology of most researchers). So, V.A. Varsonofyeva outlines three areas in the Urals: one with fresh traces of glaciation, located north of 62 ° 40 ", the other with traces of ancient glaciation (Rice), clearly visible up to 61 ° 40" N, and the third, lying south of 61°40", where the "only monuments" of glaciation are the few boulders of the strongest and most stable rocks that survived the destruction. These latter are (according to V.L. Varsonofyeva) problematic traces of the Mindel glaciation [1933; 1939 ].

Already E.S. Fedorov [1889 ] noted that “boulder sediment is very atypical in the southern parts of the North. Urals, where the nature of these deposits is the same as modern fluvial deposits of such rivers as the Nyays. In addition, in the mountainous region this sequence is so eroded that it is difficult to find small preserved areas of its former distribution” (p. 215). Such surviving sites are marked along the river. Elma, as well as along the eastern foot of the High Parma. Works by E.S. Fedorova [1890; Fedorov and Nikitin, 1901 ], V.A. Varsonofyeva [1932; 1933; 1939 ] in the basins of the Nyays, Unya, and Ilych showed that moraine occurs only sporadically in the mountainous region, and only individual erratic boulders were found on flat-topped watershed areas. The glacial landforms here are also strongly shaded, with the exception of young kars, which is explained, first of all, by the vigorous transformation of the relief by subaerial denudation in the postglacial period. Directly for the area where the authors made observations in 1939, E.S. Fedorov [1890 ] indicates (p. 16) “that many private facts hint at the presence in the past of insignificant glaciers descending from the mountains of the Central Ural Range, but not reaching significant development”, while indicating the origins of pp. Capelins and Toshemki and the area located from them to the north. At the head of the river Ivdel such traces, according to E.S. Fedorov, no.

These traces consist of “unstratified and thin sandy-argillaceous deposits abounding in boulders, and in some places just a large pile of boulders” [Fedorov, 1890]. In connection with these deposits, the presence of small lakes or simply hollows is observed on the crest of the Urals, as well as a kind of rocky edging of the beginnings of some valleys (the valley of the M. Niulas river is especially relief). “These borders can be interpreted as the remains of circuses, firn fields, and glaciers that were here.”

Even more specific are the instructions of L. Duparc, who in his works [Duparc & Pearce, 1905a; 1905b; Duparc et al., 1909] describes a number of glacial forms in the area of ​​the Konzhakovsky Kamen mountain range, located 15 km north of the Kytlym platinum mine, i.e. at a latitude of 59 ° 30 ". When describing the eastern slopes of the Tylaya (the southwestern peak 5 km from the top of the Konzhakovsky Stone), Duparc describes the sources of the rivers originating from the Tylaya. In his opinion, they may represent insignificant punishments.

On the western slope of the Tylaya, at the head of the river. Garevoy, L. Duparc describes the erosion circus. Obviously, the same erosion cut, and not a car, is a deep ravine at the top of the river. Job. He mentions ravines in the shape of a horseshoe with very steep slopes, very similar to the car.

At the top of the Serebryansky Stone, located 10 km east of the top of the Konzhakovsky Stone, a large rocky circus is described in the upper reaches of the river. V. Katysherskaya. The same cirque-shaped headwaters have the valleys of B. Konzhakovskaya and the river. Half day. The author describes in detail the form of these circuses.

It is characteristic that all the rivers of the eastern slope of the watershed - B. Katysherskaya, B. and M. Konzhakovskaya, Poludnevka and Iov have similar valleys. The rivers cut into the ancient alluvium, which begins at the very foot of the rocky slopes and reaches a thickness of up to 12-20 m. It can be assumed that this is not ancient alluvium, but glacial deposits.

In numerous sections in the area with. Pavda, L. Duparc did not find anything similar to glacial deposits, but the features of the relief at the sources of the rivers led him to the idea that the most elevated ridges, like Tylay, Konzhakovsky Kamen and Serebryansky Kamen, carried small isolated glaciers during the Ice Age, whose activity explains the peculiar relief of the sources of Konzhakovka and Poludnevka.

Insignificant traces of glacial activity were also discovered by the authors at a number of new points in the summer of 1939. For example, on the northeastern slope of the Prayer Stone (Yalping-Ner), directly below the main peak of the mountain, at an altitude of about 1000 m, there is a strongly arranged cirque-shaped depression with a slightly concave bottom and destroyed walls, open towards the valley of the river. Vizhaya. Similar forms are found between the northern and southern peaks of Mount Oika-Chakur, located 10 km north of the Prayer Stone. Here, a modern snowfield was encountered at an altitude of 800 m.

On the western slope of the Belt Stone, at the headwaters of the Kutimskaya Lampa, there is a circus-shaped depression with a flat bottom at an altitude of about 900 m, which can be considered an ancient reservoir of a large snowfield, which has now melted. At the foot of this depression there is an accumulation of boulder-pebble material, which forms wide plumes descending into the valley of the river. Lamps.

On Denezhkin Kamen there are also insignificant traces of the activity of snowfields that were recently here in the form of niches expanded with a flat bottom, located at the head of the river. Shegultan and left tributaries of the river. Sosva, above the forest zone, at an altitude of about 800-900 m. At present, the bottoms of these niches, composed of thick layers of crushed stone sediment, are cut through by deep erosion ruts.

Some cirque-shaped river tops described by L. Duparc were examined on Konzhakovsky Kamen, and the authors are inclined to consider these forms as analogs of cirque-shaped depressions on Denezhkin and Poyasovo Kamen. But in all likelihood, these depressions, which are not typical circuses, also represent receptacles of ancient snowfields, which have now melted.

Despite careful searches, the authors failed to find in the mountains of the Northern Urals south of 62° N. latitude. undoubted glacial deposits. True, at several points boulder loam was encountered, similar in appearance to normal bottom moraine. So, for example, in the valley of the river. Velsa, north of the mountain: Martai, a moraine-like rock was found in the pits of the Zauralye mine. In these loams, boulders and pebbles of only local origin were found, and, judging by the conditions of occurrence, it was possible to make sure that they compose the lower end of the deluvial plume. Absence in the river valley The wells of any moraine formations and the wide development of deluvial plumes descending from the slopes of the mountains make us attribute the found loam to deluvium.

Similar coarse deluvial loams with pebbles, and sometimes with boulders, were also found in the area of ​​the Sosva mine on the slopes of Denezhkin Kamen. Thus, the observation of E.S. Fedorov, the absence of “typical glacial deposits” in the Urals south of 61 ° 40 "was confirmed. In no case did we manage to find moraines and even erratic boulders, so characteristic of the region of the Subpolar Urals.

As an illustration of what these boulder strata are, we present a section of an outcrop located at the headwaters of the B. Capelin, east of the southern tip of Olkhovy Kamen. Apparently, the outcrop that was noted by E.S. Fedorov [1890 ] under No. 486.

Here the river flows between two mountain ranges elongated in the meridional direction - Alder Stone and Pu-Tump. The floodplain of the river cuts into older deposits that fill the bottom of the valley. The height of the outcrop edge is 5 m above the low water level of the river. In the direction of Alder Stone, the area is swampy and gradually rises. Numerous large (up to 1 m in diameter) blocks of quartzite are observed in the outcrop, occurring among fine gravel of dark gray slates with rare gabbro-diorite pebbles. The coarse clastic material is neo-rolled and cemented by yellowish-brown loamy sandy loam. Layering is clearly visible in places, however, differing from the layering of typical alluvium. This rock differs from the moraine developed, for example, in the valleys of the Subpolar Urals: 1) the presence of layering and 2) the absence of glacial processing (polishing, scars) on large blocks of quartzite (on which it is usually well preserved). In addition, it should be pointed out that the composition of the fragments here is exclusively local. True, due to the uniformity of the rocks, this feature will not be decisive in this case.

To understand the intensity of deluvial processes, interesting results were obtained from observations at the origins of pp. M. Capelin, Prayer, Vizhay and Ulsinsky Lampy. In all these cases, we are dealing with very wide bath-like valleys, turning into gentle watershed passes (M. Moiva, Ulsinskaya Lampa, Vizhay) or enclosed by more or less high massifs (Molebnaya). In the upper reaches of such valleys, it is necessary to state a very insignificant influence of modern erosion. There is no doubt that such valleys are very reminiscent of some valleys of the glacial region of the Subpolar Urals, namely those that are pumped up among lowered mountain ranges where there were no conditions necessary for the formation of kars (for example, the Pon-yu River - the right tributary of the Kozhim , Nameless rivers originating at the western foot of the Kosh-ver mountain, the sources of Khartes, etc.). The bottoms of the valleys are lined with large fragments of those rocks that emerge on the slopes of the valleys and along their bottom. The fragments are acute-angled and lie among fine gruss and sandy-argillaceous deposits, among which structural soils are sometimes observed. In these sediments, no traces of their transfer by flowing water can be seen, and only in the very channel of the river is layered alluvium with a large number of already noticeably rounded boulders observed.

When tracing the valley in the transverse direction, the gradual transition of these deposits into the deluvium of the slopes is striking. At the headwaters of M. Capelin and Ulsinskaya Lampa, long plumes of unsoddy placers are especially pronounced, elongated in the direction from the foot of the steep slopes of the valley to its lowest axial part. This testifies to the wide development of deluvial processes in the valleys as well.

Curious data illustrating the role of deluvial processes were obtained as a result of the petrographic determination of boulders at the top of the river. Prayer. Here, the eastern side of the valley is composed of quartz-quartzite conglomerates, while the western side is composed of quartzites and quartzite shales.

The analysis showed that the distribution of clastic material of the western and eastern sides is strictly marked by the channel of the river. Prayer, and only here does it mix as a result of redeposition by flowing water.

Since the trails of screes are elongated in the direction of the slope of the bedrock of the valley, i.e. they are mostly located perpendicular to the slope normal (and to the axis of the valleys), and in the valleys themselves we do not find any traces of glacial accumulation in the form of hilly-morainic landscapes, terminal moraines or eskers, then we must assume that if we are dealing here with glacial deposits, the latter are so altered by subsequent denudation and displaced from their original occurrence by deluvial processes that it is hardly possible now to separate them from deluvium.

It should also be emphasized that we absolutely do not find rounded pebbles and “river beds” above the level of the modern floodplain and the first terrace above the floodplain. Usually, only deluvial deposits are found higher up the slope, represented by unrounded (but sometimes edged) fragments of local rocks occurring in yellowish loamy sandy loam or reddish clay (southern part of the region). In the following, the term "deluvium" is widely understood to mean all loose weathering products displaced downhill under the influence of gravity, without the direct influence of flowing water, ice, or wind.

The assumption made by many authors about the erosion of moraine deposits by river waters within the entire width of the valleys of the Vishersky and Lozvinsky Urals is doubtful. On the other hand, one has to come to the conclusion that even in the valleys, deluvial processes had a very wide development.

From the foregoing, it can be seen that in the Northern Urals, south of 62 ° N, traces of glacial activity are found only in a few points, in the form of scattered, weakly expressed, rudimentary forms - mainly underdeveloped kars and receptacles of snowfields.

As you move south, these tracks become less and less. The last southern point, where there are still insignificant signs of glacial forms, is the massif of Konzhakovsky Stone.

All fresh glacial forms, widespread in the Subpolar Urals, are found, as mentioned above, only on some of the highest peaks of the Northern Urals. Therefore, the authors believe that during the last glacial epoch (Wurm) in the Visher Urals, there were only minor glaciers that did not go beyond the slopes of the highest mountain peaks.

Thus, the limited distribution of glacial forms in the mountains and the absence of any young glacial deposits in the valleys indicate that the Northern Urals in the space between 62° and 59°30" N was not subjected to continuous glaciation during the last ice age and, therefore, could not be a significant center of glaciation.

That is why deluvial formations are extremely widespread in the Northern Urals.

Let us now turn to the consideration of traces of glaciation in the peripheral parts of the Northern Urals, surrounding high-mountain regions.

As is known, on the western slope of the Urals, in the area of ​​the city of Solikamsk, glacial deposits were first established by P. Krotov [1883; 1885 ].

P. Krotov met individual glacial boulders east of the river. Kamy, in pools pp. Deaf Vl lions, Yazva, Yaiva and its tributaries - Ivaki, Chanva and Ulvicha.

In addition, Krotov describes the "glacial polish of rocks" on the river. Yaive 1.5 miles above the mouth of the river. Kadya.

All these points are still the extreme eastern points for finding traces of glacier activity. This author points out that "... After all, Cherdyn and, probably, the entire Solikamsk county should be included in the area of ​​distribution of traces of glacial phenomena." Without denying the fact that traces of glacier activity in the foothill zone are found only occasionally, Krotov, arguing with Nikitin, writes: “The very singularity of such facts is explained by the conditions in which the Urals were and are in relation to the destroyers of rocks.”

P. Krotov was one of the first to point out the importance of the Vishera Urals as an independent center of glaciation and allowed the possibility of ice movement, in contrast to the opinion of S.N. Nikitin, from the Urals to the west and southwest. In addition, Krotov correctly noted the great role of frost weathering processes in the formation of the relief of the Urals and in the destruction of traces of ancient glaciation.

On many of the latest geological maps, the boundary of the distribution of glacial deposits is shown according to the data of P. Krotov, published in 1885.

P. Krotov's conclusions about the existence of an independent Ural center of glaciation were vigorously challenged by S.N. Nikitin [1885 ], who approached the solution of this issue in a very biased way. So, for example, S.N. Nikitin wrote [1885 , p. 35]: "... Our modern knowledge of the western slope of the Urals ... gave reliable support for the decisive assertion that in the Urals before the Pechora watershed, at least, there were no glaciers in the Ice Age."

Nikitin's views influenced the researchers of the Urals for a long time. To a large extent, under the influence of Nikitin's views, many subsequent authors drew the boundary of the distribution of erratic boulders in the Urals north of 62°.

The views of S.N. Nikitin is to a certain extent confirmed by the results of M.M. Tolstikhina [1936 ], which in 1935 specifically studied the geomorphology of the Kizelovsky region. MM. Tolstikhina did not find any traces of glacial activity in the area of ​​her research, despite the fact that it is located only 20-30 km south of the places where P. Krotov describes single finds of glacial boulders. MM. Tolstikhina believes that the main surface of the studied area is pre-Quaternary peneplain.

Thus, the basins of the Kosva and upper reaches, the Vilva rivers, according to M.M. Tolstikhina, are already located in the extraglacial zone.

However, the data of P. Krotov are confirmed by the latest research.

The results of the work of the Kama-Pechora expedition in 1938 showed that the moraine of ancient glaciation is widespread over large areas on the right bank of the river. Kamy, south of the city of Solikamsk. On the left bank of the river Kamy, between the city of Solikamsk and the valley of the river. Deaf Vilva, the moraine occurs only occasionally, mainly in the form of boulder accumulations left after the erosion of the moraine. Even further east, i.e. within the hilly-ridged strip, no traces of glacial deposits have been preserved. The wedging out of glacial deposits from west to east, as they approach the Urals, is noted by V.M. Yankovsky for about 150 km, i.e. in the strip from the upper reaches of the river. Kolva to Solikamsk. The thickness of the moraine increases with the distance from the Urals to the west and northwest. Meanwhile, this moraine contains a significant amount of boulders from rocks of undoubtedly Ural origin. Obviously, the eastward wedging out of the moraine is a phenomenon of a later order, resulting from the action of intense denudation processes over a long period of time, which, undoubtedly, acted more intensively in the mountains.

On the eastern slope of the Urals, the southern boundary of the distribution of glacial deposits has not yet been finally established.

In 1887 E.S. Fedorov, in a note about the discovery of chalk and boulder deposits in the Ural part of Northern Siberia, described "traces of small glaciers descending from the crest of the Urals." The author described tarns in the upper reaches of the river. Lozva (in particular, Lake Lundhusea-tur) and hilly ridges in the basins of Northern Sosva, Manya, Ioutynya, Lepsia, Nyaysya and Leplya, which are composed of non-layered sandy clay or clayey sand with a huge number of boulders. The author pointed out that "the rocks of these boulders are real Ural."

Based on the data of E.S. Fedorova [1887 ], the border of continuous glaciation in the Urals was drawn north of 61 ° 40 "N. E.S. Fedorov and V.V. Nikitin denied the possibility of continuous glaciation of the area of ​​the Bogoslovsky mountain district [Fedorov and Nikitin, 1901 , pp. 112-114)], but allowed here, i.e. to the latitude of Denezhkin Kamen, the existence of local glaciers (alpine type).

E.S. data Fedorov are confirmed by subsequent observations of E.P. Moldavantsev, who also described traces of local glaciers south of 61 ° 40 "N. So, for example, E.P. Moldavantsev writes [1927 , p. 737)]: “In the channels of pp. Purma and Ushma, to the west of Chistop and Khoi-Ekva, among the riverbeds, consisting of rocks of the greenstone strata, it is possible to occasionally meet small boulders of coarse-grained gabbro rocks occurring to the east, which indicates the possible spread of glaciers in the direction from the named massifs to the west, i.e. against the current flow of rivers.

It should be noted that the finds of boulders confined only to the riverbed do not deserve full confidence, especially since in 1939 we did not find any traces of glacial forms on the slopes of the Chistop and Hoi-Ekva mountains that should have been preserved from the last ice age. However, the fact that this indication is not a single one forces us to pay attention to it.

To the south of the described rivers, in the area of ​​the village of Burmantova, E.P. Moldovans [1927 , p. 147)] found boulders of deep rocks - gabbro-diorites and quartz diorites, as well as boulders of metamorphic rocks: albite-micaceous gneisses, micaceous medium-grained sandstones and quartzites. E.P. Moldavantsev draws the following conclusion: “If we take into account, on the one hand, the sharp petrographic difference between the named boulders from the bedrocks of the area, their size - their appearance, and on the other hand, the wide development of similar basic deep and metamorphic rocks to the west of Burmantovo (in the distance about 25-30 km), then it becomes quite possible to assume the existence in the past at this latitude of local alpine-type glaciers advancing here from the west, i.e. from the Ural Range. The author believes that the valley of the river. Lozva partly owes its origin to the eroding activity of one of the local, probably polysynthetic glaciers. The deposits of this glacier (lateral moraines), according to E.P. Moldavantsev, destroyed by subsequent erosion.

One of the extreme southern points where glacial deposits are indicated is the area of ​​the village of Elovki, near the Nadezhda plant in the Northern Urals, where, during the exploration of a native copper deposit, E.P. Moldavaitsev and L.I. Demchuk [1931 , p. 133] indicate the development of brown viscous clays, up to 6-7 m thick, containing rare inclusions of rounded pebbles in the upper horizons, and a large amount of coarse material in the lower ones.

The glacial nature of the deposits in the area of ​​the village of Elovka is established by all collected materials and samples of collections - S.A. Yakovlev, A.L. Reingard and I.V. Danilovsky.

It can be seen from the description that these brown viscous clays are similar to those that are developed throughout the territory of the city of Serov (Nadezhdinsk Bay) and its environs. In the summer of 1939, a water pipeline was laid in the city of Serov, and in trenches up to 5-6 m deep, crossing the entire city, the authors had the opportunity to study the nature of the Quaternary cover, which rests on opoka-like Paleogene clays. The thickness of chocolate-brown and brown dense loams, 4-5 m thick, usually contains gruss and pebbles in the lower horizons, and gradually turns upwards into a typical lilac mantle loam, which in places has a characteristic loess-like columnar and porosity.

The authors were able to compare the surface deposits of the area of ​​the city of Serov with typical mantle loams from the areas of the village of. Ivdel, p. Pavda, the city of Solikamsk, the city of Cherdyn, the city of N. Tagil and others and came to the conclusion that brown loams, widely developed in the area of ​​the city of Serov, also belong to the type of mantle loams, and not to glacial deposits.

The conclusions of the authors about the absence of glacial deposits in the area of ​​the city of Serov are consistent with the data of S.V. Epshteyia, who studied the Quaternary deposits of the eastern slope of the Northern Urals in 1933 [1934 ]. S.V. Epstein explored the valleys of the river. Lozva from the mouth to the village of Pershino, the watershed between Lozva and Sosva and the basin of the river. Tours. He did not meet glacial deposits anywhere and describes only alluvial and eluvial-deluvial formations.

Until now, there are no reliable indications of the presence of glacial deposits in the plain in the Sosva, Lozva and Tavda basins.

From the above review of the material on the issue of traces of ancient glaciation in the Urals, we are convinced that within the actual Ural ridge, these traces have been preserved less than in the adjacent parts of the lowlands. As noted above, the reason for this phenomenon lies in the intensive development of deluvial processes, which destroyed the traces of ancient glaciation in the mountains.

The assumption suggests itself that the formation of the dominant landforms in the mountains is due to the same processes.

Therefore, before making final conclusions about the boundaries of maximum glaciation, it is necessary to dwell on the question of the origin of upland terraces and on elucidating the degree of intensity of frost-solifluction and deluvial processes in the mountains.

On the origin of upland terraces

Turning directly to the upland terraces, it should be emphasized that we have placed the main emphasis on the material that characterizes the genetic side of this phenomenon, including a number of important details in the structure of the upland terraces, to which L. Duparc paid no attention at all and whose significance was highlighted in a number of contemporary works [Obruchev, 1937].

We have already noted the almost universal development of upland terraces, which determines the whole character of the landscape of the Vishersky Urals, which is far from being said about the more northern parts of the Urals.

Such a predominant development of these forms in the more southern parts of the Urals alone indicates that they are hardly directly related to the activity of glaciers, as A.N. Aleshkov [Aleshkov, 1935a; Aleschkow, 1935], and even firn snowfields, because in this case we would have to expect just the opposite distribution of upland terraces within the ridge. Namely, their maximum development in the north, where glacial activity undoubtedly manifested itself more intensively and over a longer period of time.

If the upland terraces are the result of post-glacial weathering, then all the more attention should be paid to them, since in this case the relief underwent a very significant transformation in a relatively short time, losing all the signs that the former glaciation could imprint on it.

In view of the great controversy of this problem and the diversity of points of view on the origin of upland terraces, but mainly in view of the very limited number of facts underlying all the proposed hypotheses without exception, we have identified the following main issues, the solution of which certainly required the collection of additional factual material : a) connection of upland terraces with bedrock; b) the influence of slope exposure and the role of snow in the formation of upland terraces; c) the structure of the terraces and the thickness of the cloak of loose clastic deposits in various parts of upland terraces; d) the significance of permafrost phenomena and solifluction for the formation of upland terraces.

The collection of factual material was carried out over a number of years, hiding there was an opportunity to examine a large number of deep mine workings (pits and ditches) set in various parts of upland terraces, as well as to excavate structural soils.

a) On the question of the connection of upland terraces with bedrocks, their occurrence and nature of cracks which are developed in them, the collected material gives the following indications.

Upland terraces in the Urals are developed on a variety of rocks (quartzites, quartz-chlorite and other micaceous metamorphic schists, hornfels schists, green shales, gabbro-diabases, gabbro, on ultrabasic rocks, in granites, granite-gneisses, grano-diorites and diorites) , which is clear not only from our observations, but also from the observations of other authors.

The widespread opinion that the upland terraces have a selective capacity for certain breeds must be rejected. The apparent preferred development of these forms in the area of ​​quartzite outcrops (for example, in the Vishera Urals) is explained by the fact that it is these hardly weathered rocks that form the highest modern massifs here, where climatic conditions are favorable for the formation of upland terraces (see below).

As for the weak development of upland terraces on Denezhkin Kamen and Konzhakovsky Kamen, the highest insular mountains of the eastern slope in this part of the Urals, one should emphasize their much greater dissection by erosion than, for example, located to the west of Poyasovoye Kamen. The significance of erosion as a factor that negatively affects the possibility of formation of upland terraces, we will still be able to shade below.

The influence of the tectonics factor and structural features of bedrock occurrence on the development of upland terraces, after the work of S.V. Obruchev [1937 ], it would be possible not to touch it if it were not for the note by N.V. Dorofeeva [1939 ], where these factors are of decisive importance in the formation of upland terraces. It is hardly necessary to prove that in this case, taking into account the complex tectonics of the Urals, one would expect the development of upland terraces only in strictly defined zones, while we observe in the same Vishera Urals the widespread development of terraces, starting with the Poyasovyi Kamen in the east and ending with Tulymsky Stone in the west. Here, the fact that this phenomenon is entirely due to climatic factors and is primarily determined by them comes out especially clearly. This factor is completely not taken into account by N.V. Dorofeev, and therefore it is not clear why terraces do not develop in lower relief zones.

Development of upland terraces in the area of ​​the destroyed wing of the anticline in the zone of strong shearing (Karpinsky town), on folds overturned to the east (Lapcha town), in the area of ​​quartzites steeply dipping to the east and set on their heads (Poyasovy Kamen) and strata gently dipping to the east (Yarota), in the area of ​​development of significant granite massifs (Neroi massif) and gabbro outcrops, under conditions of various rock occurrences and various fissure tectonics, once again confirms that these factors are not of decisive importance for the formation of terraces.

The distribution of heights in the position of individual terraces, depending on the horizontal cracks of separation, which is indicated by N.V. Dorofeev [1939 ], is refuted by a number of facts. For example, observed everywhere in the Vishera Urals, there is a different altitudinal distribution of upland terraces on two slopes facing each other, which have exactly the same structure (the western slope of the Poyasovy Kamen at the headwaters of the Ulsinskaya Lampa). In the same place, on two similar spurs of the western slope, which have the same geological structure and are separated only by a narrow erosional valley, we observe 28 terraces on the northern spur, and only 17 well-formed terraces on the southern spur. Finally, on a relatively small terraced hill composed of gabbro-diabase (on the surface of Kvarkush), a different number of steps are observed on the slopes facing south and north. In addition, as measurements on Poyasovy Kamen show, horizontal separation in quartzites usually develops in the range from 6 to 12 m, while the difference in the levels of upland terraces ranges from 3-5 to 60 m. As we will show below, due to vigorously ongoing frost processes, the surface terraces should decrease, and, consequently, horizontal cracks of units can play a role only in the initial stages of development of upland terraces.

Instruction N.V. Dorofeeva [1939 ] that the edge of the terrace allegedly necessarily coincides with the outcrop of harder rocks, also does not find confirmation and can be easily refuted by the example of the same Belt Stone, where, following the strike of the rocks, one can observe terraces in completely homogeneous quartzites on the slopes any exposure. The same is confirmed by observations on the northern spurs of the Tulymsky Stone, on the Ant Stone, on the watershed of the Pechora Son and its right tributary, the Marina stream, and at other points. The above example with terracing of a hill folded with gabbro is also indicative. Finally, numerous observations confirm that the same terraced surface crosses the contacts of different rocks (diabases and quartzites on the Man-Chuba-Nyol mountain, maidelsteins and micaceous schists on the watershed of the Pechora Synya and Sedyu, granites and green schists on the Tender Ridge, quartzites and mica-quartzite schists at a height of 963 m, etc.). In short, terrace ledges do not necessarily coincide with the contacts of various rocks and in this respect do not reflect their distribution and tectonics, as follows from Dorofeev. Examples of the opposite only show that during weathering, the resistance of rocks plays an important role, which is why we observe that individual outcrops of harder rocks form hills (tumps) protruding above the common surface.

However, one should not forget that these hills are also terraced, although their composition is homogeneous.

b) slope exposure apparently also has no effect on the development of upland terraces, as can be seen from the data below. This circumstance is especially striking when examining Mr. Isherim and Prayer Stone (Yalpingner). There are terraced peaks of Isherim and all three of its spurs, stretched in different directions. The northeastern spurs of Isherim, in turn, are connected by a pass with the Prayer Stone, and the mountains go around the upper reaches of the river. Prayer, flowing in the direction to the north. The entire crest of the pass, forming a smooth arc, elongated to the east, and oriented in the north-south direction, the mountains of the left bank of the river. Prayer and massif Yalping-ner - terraced. Thus, here, in a relatively small area, we see beautifully formed terraces on the slopes of the most varied exposition. It should also be emphasized that for terraced mountain peaks (the uppermost levels of upland terraces), the exposure cannot have any significance at all.

However, the issue of slope exposure is very important for the distribution of snow, the role of which in the formation of terraces was especially emphasized by S.V. Obruchev [1937 ].

Snowwalls at the foot of the ledge and on the slopes of upland terraces, as shown by numerous observations in the mountains of the Subpolar and Vishera Urals, are formed on the slopes of the northern, northeastern and eastern exposures and, as an exception, on the slopes of the southern, southwestern and western. Thus, as A.N. Aleshkov [1935a], in their distribution, the decisive role belongs to the conditions of shading and the prevailing winds (western quarter). Moreover, detailed observations revealed that only those snowfields that persist for most or all of the summer have a significant impact on their receptacle (slope), causing vigorous destruction of the ledge of the upland terrace and the formation of solifluction leveling areas at the foot of the slope. Their positive role in the formation of upland terraces also lies in the fact that, having a large supply of moisture, they, giving it away during melting, gradually activate the processes of solifluction on the lower surface of the upland terrace.

However, one has to deny behind them the significance and the role that S.V. ascribed to them in the formation of upland terraces. Obruchev [1937 ]. This is confirmed by the structure of the terraces (see below) and a huge number of facts, when on two terraced slopes of directly opposite exposure, in one case, we observe summer snow faces at the foot of the terrace ledges, and in the other they are not. Meanwhile, the terraces on both slopes do not differ at all from each other in their morphological and other characteristics, as we have already noted above. The same can be clearly seen on rounded terraced hills (for example, on Kvarkush). Thus, the role of snow cannot in any way be recognized as decisive, since otherwise we would observe a noticeable asymmetry in the development of terraces depending on the exposure of the slope.

c) Go to description of the structure of upland terraces.

As shown by numerous workings, there is no fundamental difference in the structure of upland terraces of various sizes and different rocks located in the area of ​​development. This applies both to the uppermost terrace levels (truncated peaks) and to the upland terraces of the slopes located at various levels.

The structure of the terraces turned out to be so standard that the generality of the cause of their formation and independence from the bedrocks cannot be subject to any doubt. It should be noted here that some authors, for example, A.N. Aleshkov [ 1935a], following morphological features, include in the concept of upland terraces vast upland plateaus and upland valleys stretching for several tens of kilometers. These very large landforms in a number of cases undoubtedly have a different origin than the upland terraces we are describing. Forms of frost-solifluction terracing are superimposed here on more ancient landforms.

Using the terminology of S.V. Obruchev [1937 , p. 29], we will distinguish: the cliff (or slope) of the terrace, the edge and the surface of the terrace, dividing it into the frontal (adjacent to the edge), middle and rear parts.

terrace slopehas an angle of inclination from 25 to 75° (on average 35-45°) and, as a rule, a sustained fall in this area (see Fig. 4, 5). However, upon closer examination, one can see that often in the lower third the slope has a steeper drop (up to vertical). On the other hand, we can find more laid down sections of the slope, especially in the edge area. As a rule, and not as an exception, along the slope, mainly in the lower third of it, among the coarse clastic scree, bedrock outcrops are observed. Not a single pit found a thick clastic cover along the slope, as was to be expected from S.V. Obruchev [1937 ]. On the contrary, the correctness of A.I. Aleshkov, who wrote that "the ledges of upland areas are represented by outcrops of bedrock" [1935a, p. 277].

The surface of upland terraces turned out to be covered with a mantle of clastic deposits, the average thickness of which is from 1.5 to 2.5 m. It never exceeded 3.5–4 m, but bedrock often occurs at a depth of only 0.5 m. °). The thickness of the cover is usually less in the most elevated parts of the surface. But the elevated zone is by no means always confined to the rear part of the terrace surface (to the foot of the slope of the overlying terrace). It can be located in the edge area, in the center and in other places (usually an elevated part with a thin cover is located in the place where protrusions - remnants existed until recently). The flow of soil is oriented in the direction of these weak slopes and sometimes runs parallel to the foot of the slope, terrace or from the edge inward. Hence it is clear that it is far from always possible to expect zoning in the structure of terraces in the direction from the foot of the ledge to the crest.

It is quite characteristic that we do not observe accumulations of colluvium at the foot of the scarp (Figs. 2, 5), and only when the surface of the underlying terrace is strongly sodden is the foot of the scarp surrounded by an accumulation of detrital material that forms a kind of border.

d) Both the external features and the structure of the clastic cloak indisputably indicate solifluction processes flowing on the surface of the terrace and its slopes. They are expressed, first of all, in the orientation of the differentiated coarse-clastic and fine-earth material in accordance with the slope of the surface (Fig. 4). Stone strips, composed of sharp-angled coarse-grained material, alternate with earthen strips, elongated in the direction of the weak slopes of the terrace surface. However, very often earth strips are divided into separate cells of structural soils. Highly leveled upland terraces are characterized by a more or less uniform distribution (Fig. 3) of structural soil cells over the entire site. The type of structural soils remains more or less constant in different parts of the upland terraces. In addition to the slope, it depends on the quantitative ratio of fine earth and clastic material. For the latter, the size of the debris and their shape play a role.

However, some peculiarity in the types of structural soils also depends on the nature of the underlying bedrock, due to the weathering of which they arise. This is very clearly seen in cases where the terrace surface captures outcrops of various rocks. Then it can be observed that different types of structural cells are marked with a contact line. Our observations do not confirm the presence of persistent edge ramparts in the front part of the terraces (with the exception of isolated cases). The dropping of material occurs in the form of flows of stone material through the reduced sections of the edge. Apparently, no creeping and crushing occurs in the marginal zone, since the process of solifluction itself is associated with the buoyancy of the soil and proceeds only at the moments when this buoyancy takes place. Therefore, the flow of soil is carried out in the direction of least resistance. The marginal (very thin, descending to the wedge) part of the snow face, if the latter is developed, cannot in any way play the role of a stop. Solifluction will simply choose another direction (of least resistance). This is all the more so since most of the sites have three open slopes of different exposure. And if a snow face develops, then only on one of them. In addition, on high ledges, the face does not reach the edge at all or has an insignificant thickness here and melts very quickly (simultaneously with the release of the terrace surface). The absence of ramparts is also explained by the fact that the ledge itself and the edge of the terrace are steadily and vigorously receding towards themselves. The same circumstance explains the predominant occurrence of coarse-grained material along the crest and slope of upland terraces. In the stone strips directed to the edge, longitudinal axial hollows are sometimes observed. This phenomenon arises due to two reasons, often acting together. One of them is that due to the frost shear acting in opposite directions from two adjacent earth strips, deep furrows appear in the coarse-grained material, similar to those that are observed almost everywhere between individual elevated cells of structural soils. Another reason lies in the fact that these large fragmental bands are water drainage routes, and here, on the one hand, fine earth is carried out, and on the other hand, fragments are vigorously destroyed (from below) when the temperature fluctuates around the freezing point of water. As a result, the placer settles along the drainage flow line. Finally, it should also be emphasized that structural soils are secondary phenomena and rather mask the direction of soil movement in a given area. The fact that the latter actually takes place in the uppermost parts of the cover (in the active layer of permafrost) is evidenced by the displacement of rock crystals from collapsing primary nests located on the surface of the terraces. The crystals are distributed in the form of jets in the direction of a slight slope of the terrace surface. As can be seen from the inspection of numerous pits and ditches, the structure of the soil in the area of ​​the terrace area is characterized by the following features. The lowest horizon represents an uneven surface of bedrocks, covered with coarse-grained eluvium bound by permafrost. Above, there is an accumulation of fine gravel and sometimes interlayers of fine earth (yellowish loam with fine gruss), in which larger fragments lie. The upper horizon is an accumulation of debris, among which frost sorting is observed in the form of cells of structural soils (its depth does not exceed 70 cm from the surface). In some places, one can see how clay masses are squeezed upwards among larger fragments as a result of expansion of the volume - wet fine earth during freezing. Traces of the flow are noticeable within the active layer of permafrost at a depth of up to 1.5 m (but usually not more than 1 m) and are expressed in the orientation of fine gravel material parallel to the terrace surface, as well as the presence of crumples at the site of outcrops of bedrocks [Boch, 1938b; 1939]. It is also obvious that long-term seasonal permafrost (thaws only by mid-August, for only 1 month), in spring and in the first half of summer, plays the same role as permafrost, creating a water-resistant surface necessary for waterlogging the upper soil horizons and developing solifluction (Vishera Urals).

On the basis of the superimposed, it is impossible not to come to the conclusion that the received factual material is in conflict with existing hypotheses, even with those in which the role of frosty and snowy weathering and solifluction is shaded. This gives us the right to offer a somewhat different explanation for the origin and development of upland terraces, which is more consistent with the observed facts. It can be assumed that for the emergence of terraces, it is sufficient that there are outcrops of bedrock on the slope. Then, under the condition of vigorous frost damage, as a result of differential weathering or tectonics features, including cracks in parts (in homogeneous rocks), a ledge appears - a small horizontal platform and a steep slope limiting it.

A certain amount of clastic material begins to accumulate on the site. In subarctic and arctic climates, detrital material will be cemented by permafrost. Thus, already at the very beginning, for each given site, a more or less constant denudation level arises due to the preservation of the site by permafrost. The weathering conditions for a flat-horizontal platform and for a slope from this moment on become sharply different. In this case, the bare slope will vigorously collapse and retreat, while the platforms will only slowly decline. For the speed of retreat of the edge, in addition to climatic factors, exposure, composition and properties of bedrocks certainly play a role. However, these factors are of secondary importance and never decide matters. The significance of a more or less constant level of the site, however, is not only in this, but also in the fact that here, as a result of a sharp break in the profile, moisture always accumulates, flowing down the slope and appearing as a result of thawing permafrost. Thus, with temperature fluctuations around the freezing point of water, the most effective frost weathering will occur here at the foot of the slope. Hence the break in the slope profile mentioned above. But since gravity forces the fluid soil of the permafrost active zone to tend to the horizontal plane, both the foot of the ledge and the platform lie almost strictly in the horizontal plane (the role of this foot line is comparable to that attributed to the bergschrund in the formation of kars). From here, the site is obtained as a result of the retreat of the slope, and the desire of the waterlogged part of the soil to occupy the possible lowest position leads to solifluction leveling of the surface that has arisen. In general, any protrusion above the surface of the terrace will be destroyed (cut down) in the same way by frost weathering.

The role of solifluction transport is very important, since it is due to its presence that we do not observe accumulations of colluvium at the foot of the slope. The latter circumstance is of great importance in the formation of the terrace. However, it must be remembered that, due to the backward retreat of the ledge and edge, we always get a somewhat exaggerated idea of ​​the speed and significance of the solifluction ejection of material.

As a result of the gradual grinding of debris and the removal of fine earth, the areas of terraces occupying a low position are relatively enriched in fine earth.

However, it must be remembered that by no means all the clastic material resulting from the destruction of the slope falls on the surface of the underlying terrace, since the demolition is carried out not only in the direction of the lower terrace. For example, on terraced ridges, two sides of the site are usually limited by an erosion slope, towards which the deluvium is also thrown.

In the formation of terraces, in our opinion, sufficient moisture and alternate freezing and thawing and the presence of at least long-term seasonal permafrost play an important role. In this regard, it is interesting to emphasize that, according to the information collected, the surfaces of the upland terraces are almost completely bare of snow in winter, due to which the freezing of the soil occurs here especially deeply. At the same time, the slope is subject to destruction both under the snow cover and in the parts exposed from it.

Turning to generalizations, it should be pointed out that, in contrast to S.V. Obruchev, we believe that the lower terraces “eat up” the upper ones, and not vice versa (Fig. 6, 7). Most of the leveled areas along the peaks were obtained as a result of the above-described cutting of ledges by the surface of the terraces. All stages of this process can be observed on the Belt Stone with the utmost clarity. Therefore, there is no need to accept any special conditions for the upper levels of upland terraces, as S.V. Obruchev.

The emergence of terrace areas in the way indicated by G.L. Padalka [1928 ], actually takes place under the given especially favorable conditions. However, they have nothing in common with the development of frost-solifluction terraces, although the latter can develop from the relief areas of G.L. Padalki. Such rudimentary ledges, partly turning into frost-solifluction areas, are clearly visible on the southern ridge of Kentner.

The development of terraces along ridges and on relatively gentle slopes (the total slope of the order of not more than 45 °) finds an explanation for the fact that erosion processes do not interfere with the formation of terraces here, since the formation of terraces still takes time, and the destructive work of erosion is too fast. demolition interrupt the process at its very beginning. On steep slopes, solifluction processes proceed, by the way, no less intensively, although they form somewhat different forms (solifluction influxes, stone rivers).

No less significant is the question of what causes the lower level of development of the terraces. The above considerations indicate that this limit is generally climatic and is associated with the boundary of the distribution of permafrost (permafrost and long-term seasonal). However, another important factor, according to the authors, is the boundary of forest vegetation. Its presence or attack on formed terraces (in the Vishera Urals) significantly changes the mode of solifluction processes.

Ultimately, the solifluctional drift slows down and causes colluvium to accumulate at the foot of the slope. Due to this, the role of the foot line is reduced to nothing and the renewal of the slope (retreat of the edge) is less and less intensive.

We have already noted the influence of erosion above. We will only point out that it is precisely in erosion that it is often necessary to look for the reason why upland terraces are poorly developed, despite suitable climatic conditions, as follows from comparisons of the relief of Denezhkin Kamen and Poyasovoye Kamen.

It remains for us to confirm our ideas about the origin of upland terraces by tracing their distribution within the Urals. When moving from south to north, there is a progressive decrease in these forms, but at the same time a decrease in the absolute marks to which they descend (Iremel > 1100 m, Vishera Urals > 700 m, Subpolar Urals > 500 m, Novaya Zemlya > 150 m).

Naturally, frost-solifluction terracing is most clearly developed on the most elevated and sharply relief mountain ranges and falls precisely at that period (following the departure of ice) when erosion has not yet had time to dissect the relief and become the dominant agent of denudation. Abrasion (Novaya Zemlya) and crust formation (Polar and Subpolar Urals) have the same effect. But the smoothed surfaces of the ancient peneplains were also subjected to the influence of frost-solifluction processes in their parts not protected by a powerful moraine cover. In the Urals, from Iremel to Pai-Khoi, forms of "frosty peneplain" are superimposed on older landforms. Glacial forms are being transformed before our eyes under the influence of these processes. So, sharp ridges - jumpers between fresh, but already dying off caravans (the Salner and Hieroiki massifs) turn into a staircase of upland terraces.

Even on Novaya Zemlya, the mountain surfaces that have just emerged from under the ice cover are already captured by frost-solifluction terracing [Miloradovich, 1936, p. 55]. It is possible that the high terraces of Grönli have the same origin [Grönlie, 1921].

Noted by A.I. Aleshkov [1935a] the facts of finding erratic boulders on the surface of upland terraces, as our studies have shown, do not contradict the conclusions drawn, since in all cases we are dealing here with frosty to solifluction phenomena altered by the glacial relief of the demolition area, where the moraine cover on the tops and slopes of the mountains is actually was absent and could not prevent the destruction of bedrock.

Around the mountainous regions, where the processes of subaerial denudation proceeded with the greatest force, there is a peripheral zone, where the predominant type of sediment is a kind of mantle loam, in which one cannot but see the consequences of the same processes [Gerenchuk, 1939], but taking place in a slightly different physical and geographical setting. This type of weathering is characteristic of periglacial regions and indicates that these regions have not been subjected to glaciation for a long time. On the Kama-Pechora watershed and in the West Siberian lowland, only one ancient (ris) moraine is developed. The second moraine (Würm) appears north of 64°N. However, it is curious to note that in the Vishera Urals there are only fresh traces of the last phase of the last glaciation, comparable with the moment of maximum development of modern glaciers in the region of the Sablya, Manaraga, Narodnaya mountains and at the head of the Grube-yu. These forms have not yet been sufficiently altered by subaerial denudation, which literally reworked the rest of the relief (see the drawings in Duparc's article [Duparc et al., 1909] and fig. 4). It is interesting to compare this phenomenon with the tectonic movements of the Northern Urals in the Quaternary. Instruction N.A. Sirina [1939 ] on the interglacial uplift of the Urals with an amplitude of 600-700 m seems little substantiated, since the boreal transgression in the Bolshezemelskaya tundra and in the north of the West Siberian lowland falls on the interglacial time. Observations for the Vishera Ural show that here an uplift of the order of 100-200 m probably took place at the end of the Würmian time (or in the post-Würmian time). As a result, we have an incision of modern valleys into ancient valleys, transformed by deluvial processes. Thus, the uplift at the time of the last climatic depression created favorable conditions for the development of embryonic glacial forms.

findings

1) The wide development of upland terraces in the Northern Urals makes us pay attention to their origin and distribution within the entire range.

2) Upland terraces are formed in conditions of permafrost or long-term seasonal permafrost, with sufficient moisture, in arctic and subarctic climates.

3) The formation of upland terraces does not depend on the composition, conditions of occurrence and structure of crown rocks. The exposure of the slope and the location of snow faces in the formation of terraces are also not of decisive importance.

4) The upland terraces are formed as a result of frost-solifluction processes acting together. Frosty weathering causes a relatively quick understandable retreat of the slope, and solifluction causes a slower decrease in the terrace surface under the influence of planation of loose weathering products and their removal from the foot of the terrace, where the most intense weathering of bedrock occurs.

5) The processes of frost-solifluction terracing cause the transformation of the relief towards the development of a stepped profile and a general decrease in the level of mountain ranges lying above the lower boundary of the permafrost, ultimately tending to the development of "frosty peneplain".

6) The processes of terrace formation are hindered by: erosion, abrasion and caving. Therefore, terraces develop predominantly in periglacial areas in those areas where erosion and other factors of denudation have not yet become decisive.

7) In the Urals, there is a progressive decrease in upland terraces from south to north, which is explained by the earlier release of the southern part of the Northern Urals from the ice cover and the longer duration of frost-solifluction processes in the southern regions.

Forms of frost-solifluction terracing are superimposed on older, in particular, glacial landforms.

8) In the southern part of the Northern Urals, no traces of ancient glaciation have been preserved, which is explained by the development of intense frost-solifluction, deluvial and erosion processes here. Meanwhile, at the same latitude, in the piedmont ridge zone adjacent to the mountains and in the plains, traces of the activity of the ancient Ural glacier have been preserved.

In the foothill zone of the western and eastern ridges, boulders from eroded ancient glacial deposits are occasionally found on watersheds, and in the plains, i.e. in areas of weaker development of denudation processes, a continuous moraine cover of ancient glaciation has been preserved.

9) The authors establish the extreme southern points of development of glacial deposits in the plains and outline zones of intensive demolition in the mountains. These mountainous regions, despite the absence at present of traces of ancient glaciation, could play the role of ancient centers of glaciation.

Considering the orographic significance of the Northern Urals as an independent center of glaciation, the authors raise the question of clarifying the boundary of maximum glaciation in the Urals.

10) The boundary of maximum glaciation in the Urals was drawn by different authors in the range from 57 to 62 ° N. latitude. without taking into account the orographic significance of the Urals or on the basis of insignificant traces of the last ice age, etc., which indicates inconsistency in this issue. The above considerations about the genesis of upland terraces, as well as the establishment of zones of different intensity of deluvial drift, make it possible to outline the next boundary of maximum glaciation (see the attached map of Fig. 8).

S. BOČ and I. KRASNOV

ON THE BOUNDARY OF THE MAXIMUM QUATERNARY GLACIATION IN THE URALS IN THE CONNECTION WITH THE OBSERVATIONS OF MOUNTAINOUS TERRACES

Summary

1. Broad development of mountainous terraces in the North Urals attracts one "s attention to their origin and occurrence within the boundaries of the whole range.

2. The mountainous terraces are formed in the conditions of perpetually frozen grounds or continuously seasonally frozen ones in the case of sufficient moisture in the Arctic or Subarctic climate.

3. The formation of the mountainous terraces does not depend on the composition, bedding and structure of the country rocks. Exposure of a slope and location of snow drifts as well do not represent the chief factors of their formation.

4. They appear due to simultaneous effect of frost and solifluction processes. Frost, weathering causes relatively quick retreat of a slope, while solifluction effects a more moderate lowering of the terrace surface due to the leveling of disintegrated products of weathering and their removal from the foot of the terrace, where the most intense weathering of the country rocks occurs.

5. The processes of the frost-solifluction terrace formation cause a change of relief towards the working out of a step profile and general lowering of the level of mountainous massifs, which lie above the lower boundary of permanently frozen grounds, a tendency existing to work out finally a "frost peneplain".

The authors suggest lo call the mountainous terraces - the frost-solifluction terraces, which put a stress on their difference from the drift solifluction terraces.

6. The processes of terrace formation are hindered by erosion, abrasion and formation of kars. Therefore, they develop chiefly in periglacial regions on the areas, where erosion and other factors of denudation have not yet become of predominant importance.

7. In the Urals the mountainous terraces diminish progressively in number and size from the south to the north, which is explained by earlier disappearance of glacial cover in the south part of the North Urals and by more continuous activity of frost-solifluction processes in southern regions.

The forms of frost-solifluction terrace formation are superposed upon the more ancient and, particularly, on the glacial forms of the relief.

8. No traces of ancient glaciation are preserved in the south, part of the North Urals, which is explained here by an intense development of the frost-solifluction, deluvial and erosion processes. Meanwhile on the same latitude the traces of activity of ancient Uralian glacier have been preserved in the foothill zone and on the plains.

Boulders from the denudated ancient glacial deposits occur sometimes in the foothill zone on the west and east slopes and continuous cover of moraine of ancient glaciation has been preserved in plains, i.p. in the regions of weaker development of denudation.

9. The authors establish the extreme southern points of occurrence of glacial deposits in the plains and indicate the zones of intense denudation in the mountains. These mountainous regions, notwithstanding they presently show no signs of ancient glaciation, could play part of ancient-centres of glaciation.

Considering the orographic importance of the North Urals as of an independent center of glaciation, the authors put forward a question concerning a more accurate boundary of maximum glaciation in the Urals.

10. The boundary of maximum glaciation in the Urals has been drawn by different authors in the interval between 57 and 62° of the north latitude without any consideration of orographic importance of the Urals or on the basis of insignificant traces of the last glaciation which means an inconsistent treatment of the question. The mentioned above data concerning the origin of mountainous terraces, as well as the establishing of the zones of different intensity of deluvial denudation, allow to draw the following boundary of maximum glaciation shown on the map (Fig. 8).

LITERATURE

1. Aleshkov A.N. Dunite-peridotite massifs of the Polar Urals. Mat. Com. forwarder research Academy of Sciences of the USSR. No. 18. 1929.

2. Aleshkov A.N. In the Northern Urals. Proceedings of the Russian Geographical Society. 1931 vol. LXIII, no. 4, pp. 1-26.

3. Aleshkov A.N. Geological outline of the region of the Neroika Mountains. Sat. "Polar Urals", ed. SOPS AN USSR. 1937, pp. 3-55.

4. Aleshkov A.N. On the upland terraces of the Urals. Sat. "Uralsk. polar regions". Tr. Glacier. expedit., vol. IV. L.: 1935, pp. 271-292.

5. Aleshkov A.N. Mount Saber and its glaciers. Sat. "Uralsk. polar regions". Tr. Glacier. expedit., vol. IV. L .: 1935, p. 56-74.

6. Aleschkow A.N. Uber Hochterrassen des Ural. Zeichtrift fur Geomorphologie, Bd. IX, Heft . 4. 1935.

7. Backlund O.O. General overview of the activities of esped. br. Kuznetsov to the Polar Urals in the summer of 1909 Zap. Imp. AN. series VIII. v. XXV III. L. 1, St. Petersburg, 1911.

8. Boch S.G. Geomorphological outline of the district of the city of Narodnaya. Sat. "Urlsk. Subpolar regions. Tr. Glacier. expedit., vol. I V. L.: 1935. pp. 116-149.

9. Boch S.G. On finding permafrost in the Northern Urals. Nature. No. 5. 1938.

10. Boch S.G. On solifluction terraces of the Subpolar Urals (Abstract of the report read at the meeting of the Geomorphological Commission of the State Geographical Islands on February 19, 1938). Izv. State. geogr. Islands No. 3, 1938.

11. Boch S.G. On some types of deluvial deposits of the Subpolar Urals. Bull. Moscow natural islands, Geology, No. 6, 1939.

12. Varsonofyeva V.A. Geomorphological observations in the Northern Urals. Izv. State. geogr. about-va, vol. 2-3. v. LXI V, 1932.

13. Varsonofyeva V.A. On traces of glaciation in the Northern Urals. Tr. Com. according to the study Quaternary period, vol. III, 1933, pp. 81-105.

14. Varsonofyeva V.A. Quaternary deposits of the Upper Pechora basin in connection with general questions of the Quaternary geology of the Pechora region. Uchen. app. Dept. geol. Moscow state ped. in-ta, 1939, pp. 45-115.

15. Vvedensky L.V. On traces of Alpine glaciation in the North. Urals on the example of the Hoffmann glacier. For the industry owls. East, 1934.

16. Gorodkov B.N. Polar Ural in the upper turning of the river. Soubi. Tr. Bot. Museum of the Academy of Sciences of the USSR, no. XIX. 1926.

17. Gorodkov B.N. The Polar Urals in the upper reaches of the Sob and Voikara rivers. Izv. Academy of Sciences of the USSR. 1926.

18. Gorodkov B.N. Polar Urals in the upper reaches of the Voikara, Synya and Lyapina rivers. Com. forwarder research Academy of Sciences of the USSR, 1929.

19. Govorukhin V.S. Introduction to tundra. Issue. 1, M., 1934.

20. Gerenchuk K.I. Solifluction as a factor in the formation of mantle loams on moraine. Uchen. app. Moscow state university Geography, vol. 25, 1939.

21. Gromov V.I. and Mirchink G.F. Quaternary period and its fauna. Fauna of the USSR, Zoologist. Institute of the Academy of Sciences of the USSR, 1937.

22. Gronlie O.T. Contributions to the Quaternary geology of the Nowaya Zemlya. Rep. Scient. Res. norw. N. Z. Exp. 1921, No. 21. Oslo, 1921.

23. Dobrolyubova T.A., Soshkina E.D. General geological map of the European part of the USSR (Northern Urals), sheet. 123. Tr. Leningrad. geol.-hydro-geogr. trust, vol. 8, 1935.

24. Dorofeev N.V. On the issue of the genesis of upland terraces. Problems of the Arctic, No. 6, 1939, pp. 89-91.

25. Duparc L., Pearce F. Sur la presence de hautes terrasses dans l'Oural du Nord. La geography. Bull. de la Societe de Geographie, Paris, 1905.

26. Duparc L., Pearce F. Sur 1 "existence de hautes terrasses dans l'Oural du Nord. Paris, 1905.

27. Duparc L., Pearce F., Tikanowitch M. Le bassin de la haute Wichera. Geneve. 1909, p. 111.

28. Hoffmann Ernst. Der Nördliche Ural und das Küstengebirge Pai-Choi, Band I-II. 1856, St. Petersburg.

29. Zavaritsky A.N. Rai-iz peridotite massif in the Polar Urals. Vses. geol.-exp. obed., 1932, pp. 1-281.

30. Kler V.O. On the stone placers of the Urals. Zap. Uralsk. about-va loves. natural in Yekaterinburg, vol. XXXI, no. 1. 1911. p. 9.

31. Krotov P.I. Geological research on the western slope of the Cherdyn Urals, carried out on behalf of the Geological Committee in the summer of 1883. Ed. Geol. com., dep. reprint, 1883.

32. Krotov P.I. Traces of the ice age in the north-eastern part of European Russia and the Urals. Tr. islands of nature. at Kazansk. un-those, vol. XIV, no. 4, Kazan, 1885.

33. Lamakins V.V. and N.V. Sayano-Dzhida Highlands (according to research in 1928). Geography, vol. 32, no. 1-2, M., 1930, pp. 21-54.

34. Miloradovich B.V. Geological outline of the northeastern coast of Severny Island of Novaya Zemlya. Tr. Arctic. in-ta, v. XXXVIII. L., 1936.

35. Moldavantsev E.P. Deposits of platinum in the Burmantovo region in the Northern Urals. Izv. Geol. Kom., 1927, v. 46, No. 2.

36. Moldavantsev E.P., Demchuk A.I. Geological outline of the district Elovki and its deposits of native copper near the Nadezhda plant in the Northern Urals. Izv. Vses. geol.-exp. united, vol. 50, no. 90, 1931.

37. Moldavantsev E.P.. Geological outline of the Chistop and Khoi-Ekva region in the Northern Urals. Izv. Geol. Kom., 1927, vol. 46, no. 7.

38. Nikitin S.N. Limits of distribution of glacial traces in Central Russia and the Urals. Izv. Geol. Kom., vol. IV, 1885, pp. 185-222.

39. Obruchev S.V. Solifluction (upland) terraces and their genesis on the basis of work in the Chukotka region. Problems of the Arctic, no. 3-4. L.: 1937.

40. Padalka G.L. About high terraces in the Northern Urals. News. Geol. Kom., vol. III, No. 4, 1928.

41. Padalka G.L. The Payer peridotite massif in the Polar Urals. Tr. Arctic Institute. T. 47. L.: 1936.

42. Sirin N.A. Some data on the geological structure of the Lyapinsky Territory in the Subpolar Urals. Problems of the Arctic, No. 3, 1939, pp. 70-75.

43. Tolstikhina M.M. Materials for the geomorphology of the Kizelovsky region on the Western slope of the Urals. Izv. State. geogr. ob-va, v. 68, no. 3, 1936, pp. 279-313.

44. Tyulina L.N. On the phenomena associated with soil permafrost and frost weathering on Mount Iremel (Southern Urals). Izv. Geogr. islands, vol. 63, no. 2-3, L., 1931, pp. 124-144.

45. Fedorov E.S. Geological research in the Northern Urals in 1884-1886, St. Petersburg, 1890, Horn, journal, vol. I and II.

46. Fedorov E.S. Geological research in the Northern Urals in 1887-1889. (Report on the activities of the geological party of the Northern Expedition). SPb., 1889, Gorn. journal, vol. II.

47. Fedorov E.S. Note on the finding of chalk and boulder deposits in the Ural part of Northern Siberia. Izv. Geol. com., vol. 7, .1887, pp. 239-250.

48. Fedorov E.S., Nikitin V.V.. Bogoslovsky Mining District. Monograph. ed. Stasyulevich, 1901.

49. Epstein S.V. Route geological and geomorphological observations on the eastern slope of the Northern Urals. Izv. State. geogr. about-va, vol. 2, vol. 46, 1934.

50. Edelshtein Ya.S. Instruction for geomorphological study and mapping of the Urals. Ed. Glavsevmorput, L., 1936.

1. What external processes and how do they affect the relief of Russia?

The following processes influence the relief of the Earth's surface: the activity of wind, water, glaciers, the organic world and man.

2. What is weathering? What are the types of weathering?

Weathering is a set of natural processes that lead to the destruction of rocks. Weathering is conditionally divided into physical, chemical and biological.

3. What influence do flowing waters, wind, permafrost have on the relief?

Temporary (formed after rains or melting snow) and rivers erode rocks (this process is called erosion). Temporary streams of water cut through ravines. Over time, erosion can decrease, then the ravine gradually turns into a beam. Rivers form river valleys. Groundwater dissolves some rocks (limestone, chalk, gypsum, salt), resulting in the formation of caves. The destructive work of the sea is provided by the impact of waves on the shore. Wave blows form niches in the shore, and from the remains of rocks, first stony, and then a sandy beach is formed. Sometimes the waves along the coast wash up narrow spits. The wind performs three types of work: destructive (blowing and blowing loose rocks), transport (transportation of rock fragments by wind over long distances) and creative (deposition of the transferred debris and the formation of various eolian surface forms). Permafrost affects the relief, since water and ice have different densities, as a result of which freezing and thawing rocks are subject to deformation - heaving associated with an increase in the volume of water during freezing.

4. What influence did the ancient glaciation have on the relief?

Glaciers have a significant impact on the underlying surface. They smooth out uneven terrain and demolish rock fragments, and widen river valleys. In addition, they create landforms: troughs, karts, circuses, carlings, hanging valleys, "sheep's foreheads", eskers, drumlins, stained ridges, kams, etc.

5. On the map in Figure 30, determine: a) where were the main centers of glaciation; b) where the glacier flowed from these centers; c) how is the boundary of maximum ice cover; d) which territories were covered by the glacier, which did not reach.

A) The centers of glaciation were: the Scandinavian Peninsula, the islands of Novaya Zemlya, the Taimyr Peninsula. B) The movement from the center of the Scandinavian Peninsula was directed radially, but the south-easterly direction received the advantage; the glaciation of the islands of Novaya Zemlya was also radial and generally directed to the south; glaciation of the Taimyr Peninsula was directed to the southwest. C) The boundary of maximum glaciation runs along the northwestern part of Eurasia, while in the European part of Russia it is more widespread to the south than in Asia, where it is limited only to the north of the Central Siberian Plateau. D) The glacier covered the territories of the northern and central parts of the East European Plain, reached 600 north latitude in Western Siberia and 62-630 north latitude in the Serden-Siberian Plateau. The territories of the north-east of the country (Eastern Siberia and the Far East), as well as the mountain belt of Southern Siberia, the south of Western Siberia and the East European Plain, the Caucasus, were outside the glaciation zone.

6. On the map in Figure 32, trace what part of the territory of Russia is occupied by permafrost.

Approximately 65% ​​of the territory of Russia is occupied by permafrost. It is mainly distributed in Eastern Siberia and Transbaikalia; at the same time, its western border begins from the areas of the extreme north of the Pechersk lowland, then goes through the territory of Western Siberia in the region of the middle course of the Ob River, and descends to the south, where it begins at the headwaters of the right bank of the Yenisei; in the east it turns out to be limited by the Bureinsky ridge.

7. Carry out the following work but the definition of the concept of "weathering": a) give a definition you know; b) find other definitions of the concept in reference books, encyclopedias, the Internet; c) compare these definitions and formulate your own.

Weathering is the destruction of rocks. Definitions taken from the Internet: “Weathering is a set of processes of physical and chemical destruction of rocks and minerals that compose them at their place of occurrence: under the influence of temperature fluctuations, freezing cycles and chemical effects of water, atmospheric gases and organisms”; "Weathering is the process of destruction and change of rock under the conditions of the earth's surface under the influence of the mechanical and chemical effects of the atmosphere, ground and surface waters and organisms." Synthesis of my own definition and definitions taken from the Internet: "Weathering is a constant process of destruction of rocks under the influence of the external forces of the Earth, in a physical, chemical and biological way"

8. Prove that the relief changes under the influence of human activities. What arguments in your answer will be the most significant?

In the anthropogenic impact on the relief, there are: A) technogenic destruction of rocks, through the extraction of minerals and the creation of quarries, mines, adits; B) movement of rocks - transportation of the necessary minerals, unnecessary soils during the construction of buildings, etc.; C) the accumulation of displaced rocks, for example, the construction of a dam, a dam, the formation of waste heaps (dumps) of empty, unnecessary rocks.

9. What relief-forming processes are most typical in the modern period for your area? What are they due to?

In the Chelyabinsk region, at the present time, all types of weathering can be found: physical - the destruction of the Ural Mountains with constantly blowing winds, also constant temperature changes lead to the physical destruction of rocks, the flowing waters of mountain rivers, although slowly but constantly expand the channel and increase river valleys , in the east of the region every spring, with heavy snowmelt, ravines are formed. Also on the border with the Republic of Bashkortostan, in the mountainous regions, processes of karstization occur - the formation of caves. Also, biological weathering occurs on the territory of the region, so in the east beavers create dams, sometimes peat deposits burn out in swamps, forming voids. The developed mining industry of the region has a strong impact on the relief, creating quarries and mines, waste heaps and dumps, leveling uplifts.

One of the mysteries of the Earth, along with the emergence of Life on it and the extinction of dinosaurs at the end of the Cretaceous period, is - Great Glaciations.

It is believed that glaciations are repeated on Earth regularly every 180-200 million years. Traces of glaciation are known in deposits that are billions and hundreds of millions of years ago - in the Cambrian, in the Carboniferous, in the Triassic-Permian. The fact that they could be, "say" the so-called tillites, breeds very similar to moraine last one, to be exact. last glaciations. These are the remains of ancient deposits of glaciers, consisting of a clay mass with inclusions of large and small boulders scratched during movement (hatched).

Separate layers tillites, found even in equatorial Africa, can reach power of tens and even hundreds of meters!

Signs of glaciation have been found on different continents - in Australia, South America, Africa and India which is used by scientists to reconstruction of paleocontinents and are often cited as evidence theories of plate tectonics.

Traces of ancient glaciations indicate that continental-scale glaciations- this is not at all a random phenomenon, it is a natural phenomenon that occurs under certain conditions.

The last of the ice ages began almost a million years ago, in the Quaternary time, or the Quaternary period, the Pleistocene was marked by the extensive distribution of glaciers - Great Glaciation of the Earth.

Under thick, many kilometers of ice covers were the northern part of the North American continent - the North American ice sheet, reaching a thickness of up to 3.5 km and extending to about 38 ° north latitude and a significant part of Europe, on which (ice cover up to 2.5-3 km thick) . On the territory of Russia, the glacier descended in two huge tongues along the ancient valleys of the Dnieper and Don.

Partially, the glaciation also covered Siberia - there was mainly the so-called "mountain-valley glaciation", when glaciers did not cover the entire space with a powerful cover, but were only in the mountains and foothill valleys, which is associated with a sharply continental climate and low temperatures in Eastern Siberia . But almost all of Western Siberia, due to the fact that the rivers were springing up and their flow into the Arctic Ocean stopped, turned out to be under water, and was a huge sea-lake.

In the Southern Hemisphere, under the ice, as now, was the entire Antarctic continent.

During the period of maximum distribution of Quaternary glaciation, glaciers covered over 40 million km 2–about a quarter of the entire surface of the continents.

Having reached the greatest development about 250 thousand years ago, the Quaternary glaciers of the Northern Hemisphere began to gradually decrease, as the glacial period was not continuous throughout the Quaternary period.

There are geological, paleobotanical and other evidence that glaciers disappeared several times, replaced by epochs. interglacial when the climate was even warmer than today. However, the warm epochs were replaced by cold spells, and the glaciers spread again.

Now we live, apparently, at the end of the fourth epoch of the Quaternary glaciation.

But in Antarctica, glaciation arose millions of years before the time when glaciers appeared in North America and Europe. In addition to climatic conditions, this was facilitated by the high mainland that existed here for a long time. By the way, now, due to the fact that the thickness of the glacier of Antarctica is huge, the continental bed of the "ice continent" is in some places below sea level ...

Unlike the ancient ice sheets of the Northern Hemisphere, which disappeared and reappeared, the Antarctic ice sheet has changed little in its size. The maximum glaciation of Antarctica was only one and a half times greater than the modern one in terms of volume, and not much more in area.

Now about the hypotheses ... There are hundreds, if not thousands, of hypotheses why glaciations occur, and whether they were at all!

Usually put forward the following main scientific hypotheses:

• Volcanic eruptions, leading to a decrease in the transparency of the atmosphere and cooling throughout the Earth;
• Epochs of orogeny (mountain building);
• Reducing the amount of carbon dioxide in the atmosphere, which reduces the "greenhouse effect" and leads to cooling;
• The cyclical activity of the Sun;
• Changes in the position of the Earth relative to the Sun.

But, nevertheless, the causes of glaciation have not been finally clarified!

It is assumed, for example, that glaciation begins when, with an increase in the distance between the Earth and the Sun, around which it rotates in a slightly elongated orbit, the amount of solar heat received by our planet decreases, i.e. Glaciation occurs when the Earth passes the point in its orbit that is farthest from the Sun.

However, astronomers believe that changes in the amount of solar radiation hitting the Earth alone are not enough to start an ice age. Apparently, fluctuations in the activity of the Sun itself also matter, which is a periodic, cyclic process, and changes every 11-12 years, with a cycle of 2-3 years and 5-6 years. And the largest cycles of activity, as established by the Soviet geographer A.V. Shnitnikov - approximately 1800-2000 years.

There is also a hypothesis that the emergence of glaciers is associated with certain parts of the Universe through which our solar system passes, moving with the entire Galaxy, either filled with gas, or “clouds” of cosmic dust. And it is likely that "space winter" on Earth occurs when the globe is at the point furthest from the center of our Galaxy, where there are accumulations of "cosmic dust" and gas.

It should be noted that usually before the epochs of cooling there are always epochs of warming, and there is, for example, the hypothesis that the Arctic Ocean, due to warming, is sometimes completely freed from ice (by the way, this is happening now), increased evaporation from the surface of the ocean , currents of humid air are directed to the polar regions of America and Eurasia, and snow falls over the cold surface of the Earth, which does not have time to melt in a short and cold summer. This is how ice sheets form on the continents.

But when, as a result of the transformation of part of the water into ice, the level of the World Ocean drops by tens of meters, the warm Atlantic Ocean ceases to communicate with the Arctic Ocean, and it gradually becomes covered with ice again, evaporation from its surface stops abruptly, less and less snow falls on the continents and less, the "feeding" of glaciers is deteriorating, and the ice sheets begin to melt, and the level of the World Ocean rises again. And again the Arctic Ocean connects with the Atlantic, and again the ice cover began to gradually disappear, i.e. the cycle of development of the next glaciation begins anew.

Yes, all these hypotheses quite possible, but so far none of them can be confirmed by serious scientific facts.

Therefore, one of the main, fundamental hypotheses is climate change on the Earth itself, which is associated with the above hypotheses.

But it is quite possible that the processes of glaciation are associated with the combined impact of various natural factors, which could act jointly and replace each other, and it is important that, having begun, glaciations, like “wound clocks”, are already developing independently, according to their own laws, sometimes even “ignoring” some climatic conditions and patterns.

And the ice age that began in the Northern Hemisphere about 1 million years back, not finished yet, and we, as already mentioned, live in a warmer period of time, in interglacial.

Throughout the epoch of the Great Glaciations of the Earth, the ice either receded or advanced again. On the territory of both America and Europe, there were, apparently, four global ice ages, between which there were relatively warm periods.

But the complete retreat of the ice occurred only about 20 - 25 thousand years ago, but in some areas the ice lingered even longer. The glacier retreated from the area of ​​modern St. Petersburg only 16 thousand years ago, and in some places in the North small remnants of the ancient glaciation have survived to this day.

Note that modern glaciers cannot be compared with the ancient glaciation of our planet - they occupy only about 15 million square meters. km, i.e. less than one-thirtieth of the earth's surface.

How can you determine whether there was a glaciation in a given place on the Earth or not? This is usually quite easy to determine by the peculiar forms of geographical relief and rocks.

Large accumulations of huge boulders, pebbles, boulders, sands and clays are often found in the fields and forests of Russia. They usually lie directly on the surface, but they can also be seen in the cliffs of ravines and in the slopes of river valleys.

By the way, one of the first who tried to explain how these deposits were formed was the outstanding geographer and anarchist theorist, Prince Peter Alekseevich Kropotkin. In his work "Investigations on the Ice Age" (1876), he argued that the territory of Russia was once covered by huge ice fields.

If we look at the physical and geographical map of European Russia, then in the location of hills, hills, basins and valleys of large rivers, we can notice some patterns. So, for example, the Leningrad and Novgorod regions from the south and east are, as it were, limited Valdai Upland, which has the form of an arc. This is exactly the line where, in the distant past, a huge glacier, advancing from the north, stopped.

To the southeast of the Valdai Upland is the slightly winding Smolensk-Moscow Upland, stretching from Smolensk to Pereslavl-Zalessky. This is another of the boundaries of the distribution of sheet glaciers.

Numerous hilly winding uplands are also visible on the West Siberian Plain - "manes", also evidence of the activity of ancient glaciers, more precisely glacial waters. Many traces of stops of moving glaciers flowing down the mountain slopes into large basins have been found in Central and Eastern Siberia.

It is difficult to imagine ice several kilometers thick on the site of the current cities, rivers and lakes, but, nevertheless, the glacial plateaus were not inferior in height to the Urals, the Carpathians or the Scandinavian mountains. These gigantic and, moreover, mobile masses of ice influenced the entire natural environment - relief, landscapes, river flow, soils, vegetation and wildlife.

It should be noted that in Europe and the European part of Russia from the geological epochs preceding the Quaternary period - the Paleogene (66-25 million years) and the Neogene (25-1.8 million years) practically no rocks were preserved, they were completely eroded and redeposited during the Quaternary, or as it is often called, Pleistocene.

Glaciers originated and moved from Scandinavia, the Kola Peninsula, the Polar Urals (Pai-Khoi) and the islands of the Arctic Ocean. And almost all the geological deposits that we see on the territory of Moscow are moraine, more precisely moraine loams, sands of various origins (water-glacial, lake, river), huge boulders, as well as cover loams - all this is evidence of the powerful impact of the glacier.

On the territory of Moscow, traces of three glaciations can be distinguished (although there are many more of them - different researchers distinguish from 5 to several dozen periods of advances and retreats of ice):

• Okskoe (about 1 million years ago),
• Dnieper (about 300 thousand years ago),
• Moscow (about 150 thousand years ago).

Valdai the glacier (disappeared only 10 - 12 thousand years ago) "did not reach Moscow", and the deposits of this period are characterized by water-glacial (fluvio-glacial) deposits - mainly the sands of the Meshchera lowland.

And the names of the glaciers themselves correspond to the names of those places to which the glaciers reached - to the Oka, the Dnieper and the Don, the Moscow River, Valdai, etc.

Since the thickness of the glaciers reached almost 3 km, one can imagine what a colossal work he did! Some elevations and hills on the territory of Moscow and the Moscow region are powerful (up to 100 meters!) Deposits that the glacier “brought”.

The best known, for example Klinsko-Dmitrovskaya moraine ridge, separate hills on the territory of Moscow ( Vorobyovy Gory and Teplostan Upland). Huge boulders weighing up to several tons (for example, the Maiden's Stone in Kolomenskoye) are also the result of the work of the glacier.

Glaciers smoothed out uneven terrain: they destroyed hills and ridges, and the resulting rock fragments filled depressions - river valleys and lake basins, transferring huge masses of stone fragments over a distance of more than 2 thousand km.

However, huge masses of ice (considering its colossal thickness) pressed so hard on the underlying rocks that even the strongest of them could not withstand and collapsed.

Their fragments were frozen into the body of a moving glacier and, like emery, scratched rocks composed of granites, gneisses, sandstones and other rocks for tens of thousands of years, developing depressions in them. Until now, numerous glacial furrows, "scars" and glacial polishing on granite rocks, as well as long hollows in the earth's crust, subsequently occupied by lakes and swamps, have been preserved. An example is the countless depressions of the lakes of Karelia and the Kola Peninsula.

But glaciers did not plow out all the rocks on their way. The destruction was mainly those areas where the ice sheets originated, grew, reached a thickness of more than 3 km and from where they began their movement. The main center of glaciation in Europe was Fennoscandia, which included the Scandinavian mountains, the plateaus of the Kola Peninsula, as well as the plateaus and plains of Finland and Karelia.

Along the way, the ice was saturated with fragments of destroyed rocks, and they gradually accumulated both inside the glacier and under it. When the ice melted, masses of debris, sand and clay remained on the surface. This process was especially active when the movement of the glacier stopped and the melting of its fragments began.

At the edge of glaciers, as a rule, water flows arose, moving along the surface of the ice, in the body of the glacier and under the ice layer. Gradually, they merged, forming whole rivers, which, over thousands of years, formed narrow valleys and washed away a lot of clastic material.

As already mentioned, the forms of glacial relief are very diverse. For moraine plains many ridges and ridges are characteristic, indicating the stops of moving ice and the main form of relief among them are shafts of terminal moraines, usually these are low arched ridges composed of sand and clay with an admixture of boulders and pebbles. The depressions between the ridges are often occupied by lakes. Sometimes among the moraine plains one can see outcasts- blocks hundreds of meters in size and weighing tens of tons, giant pieces of the glacier bed, transferred by it over great distances.

Glaciers often blocked the flow of rivers and near such "dams" huge lakes arose, filling the depressions of river valleys and depressions, which often changed the direction of river flow. And although such lakes existed for a relatively short time (from a thousand to three thousand years), they managed to accumulate on their bottom lake clays, layered precipitation, counting the layers of which, one can clearly distinguish the periods of winter and summer, as well as how many years these precipitations accumulated.

In the era of the last Valdai glaciation arose Upper Volga glacial lakes(Mologo-Sheksninskoe, Tverskoe, Verkhne-Molozhskoe, etc.). At first, their waters had a flow to the southwest, but with the retreat of the glacier, they were able to flow to the north. Traces of the Mologo-Sheksninskoye Lake remained in the form of terraces and coastlines at an altitude of about 100 m.

There are very numerous traces of ancient glaciers in the mountains of Siberia, the Urals, and the Far East. As a result of ancient glaciation, 135-280 thousand years ago, sharp peaks of mountains appeared - "gendarmes" in Altai, in the Sayans, the Baikal and Transbaikalia, in the Stanovoy Highlands. The so-called "reticulate type of glaciation" prevailed here, i.e. if one could look from a bird's eye view, one could see how ice-free plateaus and mountain peaks rise against the background of glaciers.

It should be noted that during the periods of glacial epochs, rather large ice massifs were located on part of the territory of Siberia, for example, on Severnaya Zemlya archipelago, in the Byrranga mountains (Taimyr Peninsula), as well as on the Putorana Plateau in northern Siberia.

Extensive mountain-valley glaciation was 270-310 thousand years ago Verkhoyansk Range, Okhotsk-Kolyma Highlands and in the mountains of Chukotka. These areas are considered glaciation centers of Siberia.

Traces of these glaciations are numerous bowl-shaped depressions of mountain peaks - circuses or karts, huge moraine shafts and lake plains in place of melted ice.

In the mountains, as well as on the plains, lakes arose near ice dams, periodically the lakes overflowed, and giant masses of water rushed at incredible speed through low watersheds into neighboring valleys, crashing into them and forming huge canyons and gorges. For example, in Altai, in the Chuya-Kurai depression, “giant ripples”, “boilers of drilling”, gorges and canyons, huge outlier blocks, “dry waterfalls” and other traces of water streams escaping from ancient lakes “only - just "12-14 thousand years ago.

"Intruding" from the north on the plains of Northern Eurasia, the ice sheets either penetrated far to the south along the depressions of the relief, or stopped at some obstacles, for example, hills.

Probably, it is not yet possible to determine exactly which of the glaciations was the “greatest”, however, it is known, for example, that the Valdai glacier was sharply inferior in area to the Dnieper glacier.

The landscapes at the borders of the sheet glaciers also differed. So, in the Oka epoch of glaciation (500-400 thousand years ago), to the south of them there was a strip of Arctic deserts about 700 km wide - from the Carpathians in the west to the Verkhoyansk Range in the east. Even further, 400-450 km to the south, stretched cold forest-steppe, where only such unpretentious trees as larches, birches and pines could grow. And only at the latitude of the Northern Black Sea region and Eastern Kazakhstan did comparatively warm steppes and semi-deserts begin.

In the era of the Dnieper glaciation, the glaciers were much larger. Tundra-steppe (dry tundra) with a very harsh climate stretched along the edge of the ice cover. The average annual temperature approached minus 6°C (for comparison: in the Moscow region, the average annual temperature is currently about +2.5°C).

The open space of the tundra, where in winter there was little snow and severe frosts, cracked, forming the so-called "permafrost polygons", which in plan resemble a wedge in shape. They are called "ice wedges", and in Siberia they often reach a height of ten meters! Traces of these "ice wedges" in ancient glacial deposits "speak" of the harsh climate. Traces of permafrost, or cryogenic impact, are also visible in the sands, these are often disturbed, as if “torn” layers, often with a high content of iron minerals.

Water-glacial deposits with traces of cryogenic impact

The last "Great Glaciation" has been studied for over 100 years. Many decades of hard work of outstanding researchers were spent on collecting data on its distribution on the plains and in the mountains, on mapping terminal moraine complexes and traces of glacier-dammed lakes, glacial scars, drumlins, and “hilly moraine” areas.

True, there are researchers who generally deny the ancient glaciations, and consider the glacial theory to be erroneous. In their opinion, there was no glaciation at all, but there was “a cold sea on which icebergs floated”, and all glacial deposits are just bottom sediments of this shallow sea!

Other researchers, "recognizing the general validity of the theory of glaciations", however, doubt the correctness of the conclusion about the grandiose scales of the glaciations of the past, and the conclusion about the ice sheets that leaned on the polar continental shelves is especially strong distrust, they believe that there were "small ice caps of the Arctic archipelagos”, “bare tundra” or “cold seas”, and in North America, where the largest “Laurentian ice sheet” in the Northern Hemisphere has long been restored, there were only “groups of glaciers merged at the bases of domes”.

For Northern Eurasia, these researchers recognize only the Scandinavian ice sheet and isolated "ice caps" of the Polar Urals, Taimyr and the Putorana Plateau, and in the mountains of temperate latitudes and Siberia - only valley glaciers.

And some scientists, on the contrary, “reconstruct” “giant ice sheets” in Siberia, which are not inferior in size and structure to the Antarctic.

As we have already noted, in the Southern Hemisphere, the Antarctic ice sheet extended to the entire continent, including its underwater margins, in particular, the regions of the Ross and Weddell seas.

The maximum height of the Antarctic ice sheet was 4 km, i.e. was close to modern (now about 3.5 km), the area of ​​ice increased to almost 17 million square kilometers, and the total volume of ice reached 35-36 million cubic kilometers.

Two more large ice sheets were in South America and New Zealand.

The Patagonian Ice Sheet was located in the Patagonian Andes, their foothills and on the neighboring continental shelf. Today it is reminded of by the picturesque fjord relief of the Chilean coast and the residual ice sheets of the Andes.

"South Alpine Complex" New Zealand- was a reduced copy of the Patagonian. It had the same shape and also advanced to the shelf, on the coast it developed a system of similar fjords.

In the Northern Hemisphere, during periods of maximum glaciation, we would see huge arctic ice sheet resulting from the union North American and Eurasian covers into a single glacial system, and an important role was played by floating ice shelves, especially the Central Arctic ice shelf, which covered the entire deep-water part of the Arctic Ocean.

The largest elements of the Arctic ice sheet were the Laurentian Shield of North America and the Kara Shield of Arctic Eurasia, they had the form of giant plano-convex domes. The center of the first of them was located over the southwestern part of the Hudson Bay, the peak rose to a height of more than 3 km, and its eastern edge extended to the outer edge of the continental shelf.

The Kara ice sheet occupied the entire area of ​​the modern Barents and Kara Seas, its center lay over the Kara Sea, and the southern marginal zone covered the entire north of the Russian Plain, Western and Central Siberia.

Of the other elements of the Arctic cover, the East Siberian Ice Sheet which spread on the shelves of the Laptev, East Siberian and Chukchi seas and was larger than the Greenland ice sheet. He left traces in the form of large glaciodislocations New Siberian Islands and the Tiksi region, are also associated with grandiose glacial-erosion forms of Wrangel Island and the Chukotka Peninsula.

So, the last ice sheet of the Northern Hemisphere consisted of more than a dozen large ice sheets and many smaller ones, as well as of the ice shelves that united them, floating in the deep ocean.

The periods of time in which glaciers disappeared, or were reduced by 80-90%, are called interglacials. The landscapes freed from ice in a relatively warm climate were transformed: the tundra retreated to the northern coast of Eurasia, and the taiga and broad-leaved forests, forest-steppes and steppes occupied a position close to the modern one.

Thus, over the past million years, the nature of Northern Eurasia and North America has repeatedly changed its appearance.

Boulders, crushed stone and sand, frozen into the bottom layers of a moving glacier, acting as a giant “file”, smoothed, polished, scratched granites and gneisses, and peculiar strata of boulder loams and sands formed under the ice, characterized by high density associated with the impact of glacial load - the main, or bottom moraine.

Since the dimensions of the glacier are determined balance between the amount of snow that falls on it annually, which turns into firn, and then into ice, and what does not have time to melt and evaporate during the warm seasons, then as the climate warms, the edges of the glaciers recede to new, “equilibrium boundaries”. The end parts of the glacial tongues stop moving and gradually melt, and the boulders, sand and loam included in the ice are released, forming a shaft that repeats the outlines of the glacier - terminal moraine; the other part of the clastic material (mainly sand and clay particles) is carried out by melt water flows and is deposited around in the form fluvioglacial sand plains (zandrov).

Similar flows also act in the depths of glaciers, filling cracks and intraglacial caverns with fluvioglacial material. After the melting of glacial tongues with such filled voids on the earth's surface, chaotic heaps of hills of various shapes and compositions remain on top of the melted bottom moraine: ovoid (when viewed from above) drumlins, elongated like railway embankments (along the axis of the glacier and perpendicular to the terminal moraines) ozes and irregular shape kamy.

All these forms of the glacial landscape are very clearly represented in North America: the boundary of ancient glaciation is marked here by a terminal moraine ridge with heights of up to fifty meters, stretching across the entire continent from its eastern coast to its western one. To the north of this "Great Ice Wall" glacial deposits are represented mainly by moraine, and to the south of it - by a "cloak" of fluvioglacial sands and pebbles.

As for the territory of the European part of Russia, four epochs of glaciation have been identified, and for Central Europe, four glacial epochs have also been identified, named after the corresponding alpine rivers - gunz, mindel, riss and wurm, and in North America Nebraska, Kansas, Illinois and Wisconsin glaciations.

Climate periglacial(surrounding the glacier) territories was cold and dry, which is fully confirmed by paleontological data. In these landscapes, a very specific fauna appears with a combination of cryophilic (cold-loving) and xerophilic (dry-loving) plants – tundra-steppe.

Now similar natural zones, similar to periglacial ones, have been preserved in the form of so-called relic steppes- islands among the taiga and forest-tundra landscape, for example, the so-called alasy Yakutia, the southern slopes of the mountains of northeastern Siberia and Alaska, as well as the cold, arid highlands of Central Asia.

tundrosteppe differed in that it the herbaceous layer was formed mainly not by mosses (as in the tundra), but by grasses, and it was here that formed cryophilic version herbaceous vegetation with a very high biomass of grazing ungulates and predators - the so-called "mammoth fauna".

In its composition, various types of animals were fancifully mixed, both characteristic of tundra – reindeer, caribou, musk ox, lemmings, for steppes - saiga, horse, camel, bison, ground squirrels, as well as mammoths and woolly rhinos, saber-toothed tiger - smilodon, and giant hyena.

It should be noted that many climatic changes were repeated as if "in miniature" in the memory of mankind. These are the so-called "Little Ice Ages" and "Interglacials".

For example, during the so-called "Little Ice Age" from 1450 to 1850, glaciers everywhere advanced, and their size exceeded modern ones (snow cover appeared, for example, in the mountains of Ethiopia, where it is not now).

And in the preceding "Little Ice Age" Atlantic optimum(900-1300) glaciers, on the contrary, decreased, and the climate was noticeably milder than the current one. Recall that it was at that time that the Vikings called Greenland the “Green Land”, and even settled it, and also reached the coast of North America and the island of Newfoundland on their boats. And the Novgorod merchants-Ushkuiniki passed through the "Northern Sea Route" to the Gulf of Ob, founding the city of Mangazeya there.

And the last retreat of the glaciers, which began over 10 thousand years ago, is well remembered by people, hence the legends of the Flood, so a huge amount of melt water rushed down to the south, rains and floods became frequent.

In the distant past, the growth of glaciers occurred in epochs with low air temperature and increased humidity, the same conditions developed in the last centuries of the last era, and in the middle of the last millennium.

And about 2.5 thousand years ago, a significant cooling of the climate began, the Arctic islands were covered with glaciers, in the countries of the Mediterranean and the Black Sea at the turn of the eras, the climate was colder and more humid than now.

In the Alps in the 1st millennium BC. e. glaciers moved to lower levels, cluttered mountain passes with ice and destroyed some high-lying villages. It was during this era that glaciers in the Caucasus became sharply activated and grew.

But by the end of the 1st millennium, climate warming began again, mountain glaciers retreated in the Alps, the Caucasus, Scandinavia and Iceland.

The climate began to seriously change again only in the 14th century, glaciers began to grow rapidly in Greenland, the summer thawing of the soil became more and more short-lived, and by the end of the century permafrost was firmly established here.

From the end of the 15th century, the growth of glaciers began in many mountainous countries and polar regions, and after the relatively warm 16th century, severe centuries came, and were called the Little Ice Age. In the south of Europe, severe and long winters often repeated, in 1621 and 1669 the Bosporus froze, and in 1709 the Adriatic Sea froze off the coast. But the "Little Ice Age" ended in the second half of the 19th century and a relatively warm era began, which continues to this day.

Note that the warming of the 20th century is especially pronounced in the polar latitudes of the Northern Hemisphere, and fluctuations in glacial systems are characterized by the percentage of advancing, stationary and retreating glaciers.

For example, for the Alps there are data covering the entire past century. If the proportion of advancing alpine glaciers in the 40-50s of the XX century was close to zero, then in the mid-60s of the XX century, about 30% of the surveyed glaciers advanced here, and in the late 70s of the XX century - 65-70%.

Their similar state indicates that the anthropogenic (technogenic) increase in the content of carbon dioxide, methane and other gases and aerosols in the atmosphere in the 20th century did not affect the normal course of global atmospheric and glacial processes. However, at the end of the last, twentieth century, glaciers began to retreat everywhere in the mountains, and the ice of Greenland began to melt, which is associated with climate warming, and which especially intensified in the 1990s.

It is known that the increased amount of technogenic emissions of carbon dioxide, methane, freon and various aerosols into the atmosphere seems to be helping to reduce solar radiation. In this regard, “voices” appeared, first of journalists, then of politicians, and then of scientists about the beginning of a “new ice age”. Ecologists "sounded the alarm", fearing "the coming anthropogenic warming" due to the constant growth of carbon dioxide and other impurities in the atmosphere.

Yes, it is well known that an increase in CO 2 leads to an increase in the amount of retained heat and thereby increases the air temperature near the Earth's surface, forming the notorious "greenhouse effect".

Some other gases of technogenic origin have the same effect: freons, nitrogen oxides and sulfur oxides, methane, ammonia. But, nevertheless, far from all carbon dioxide remains in the atmosphere: 50-60% of industrial CO 2 emissions end up in the ocean, where they are quickly assimilated by animals (corals in the first place), and of course, assimilated by plants–remember the process of photosynthesis: plants absorb carbon dioxide and release oxygen! Those. the more carbon dioxide - the better, the higher the percentage of oxygen in the atmosphere! By the way, this has already happened in the history of the Earth, in the Carboniferous period ... Therefore, even a multiple increase in the concentration of CO 2 in the atmosphere cannot lead to the same multiple increase in temperature, since there is a certain natural control mechanism that sharply slows down the greenhouse effect at high concentrations of CO 2.

So all the numerous “scientific hypotheses” about the “greenhouse effect”, “rising the level of the World Ocean”, “changes in the course of the Gulf Stream”, and of course the “coming Apocalypse” are mostly imposed on us “from above”, by politicians, incompetent scientists, illiterate journalists, or simply science swindlers. The more you intimidate the population, the easier it is to sell goods and manage ...

But in fact, a normal natural process is taking place - one stage, one climatic epoch is replaced by another, and there is nothing strange in this ... And the fact that natural disasters occur, and that there are supposedly more of them - tornadoes, floods, etc. - so another 100-200 years ago, vast areas of the Earth were simply uninhabited! And now there are more than 7 billion people, and they often live where exactly floods and tornadoes are possible - along the banks of rivers and oceans, in the deserts of America! Moreover, remember that natural disasters have always been, and even ruined entire civilizations!

And as for the opinions of scientists, which both politicians and journalists like to refer to so much ... Back in 1983, American sociologists Randall Collins and Sal Restivo wrote in plain text in their famous article “Pirates and Politicians in Mathematics”: “... There is no fixed set of norms that guide the behavior of scientists. Only the activity of scientists (and other types of intellectuals related to them) is unchanged, aimed at acquiring wealth and fame, as well as gaining the opportunity to control the flow of ideas and impose their own ideas on others ... The ideals of science do not predetermine scientific behavior, but arise from the struggle for individual success in various conditions of competition ... ".

And a little more about science ... Various large companies often provide grants for so-called "research" in certain areas, but the question arises - how competent is the person conducting the research in this area? Why was he chosen out of hundreds of scientists?

And if a certain scientist, a “certain organization”, for example, orders “some research on the safety of nuclear energy”, then it goes without saying that this scientist will be forced to “listen” to the customer, since he has “quite certain interests”, and it is understandable that he, most likely, will “adjust” “his conclusions” for the customer, since the main question is already not a question of scientific research–what does the customer want to get, what result. And if the result of the customer not satisfied, then this scientist will no longer be invited, and not in any "serious project", i.e. "monetary", he will no longer participate, as they will invite another scientist, more "compliant" ... Much, of course, depends on the citizenship, and professionalism, and reputation as a scientist ... But let's not forget how much they "receive" in Russia scientists... Yes, in the world, in Europe and in the USA, a scientist lives mainly on grants... And any scientist also "wants to eat."

In addition, the data and opinions of one scientist, albeit a major specialist in his field, are not a fact! But if the research is confirmed by some scientific groups, institutes, laboratories, t only then can research be worthy of serious attention.

Unless of course these "groups", "institutes" or "laboratories" were not funded by the customer of this study or project ...

A.A. Kazdym,
candidate of geological and mineralogical sciences, member of MOIP

DO YOU LIKE THE MATERIAL? SUBSCRIBE TO OUR EMAIL NEWSLETTER:

We will send you a digest of the most interesting materials of our site by email.

The land surface was repeatedly subjected to continental glaciation (Fig. 110). Evidence of the repeated glaciations on the plain in the Pleistocene is the presence of remains of relatively heat-loving plants in the intermorainic deposits.
In the era of maximum glaciation, glaciers covered more than 30% of the land area. In the northern hemisphere, they were located in the northern parts of Europe and America. The main centers of glaciation in Eurasia were on the Scandinavian Peninsula, Novaya Zemlya, the Urals and Taimyr. In North America, the centers of glaciation were the Cordillera, Labrador, and the area west of the Hudson Bay (Kivatinsky Center).
In the relief of the plains, traces of the last glaciation (which ended 10 thousand years ago) are most clearly expressed: Valdai - on the Russian Plain, Wurm - in the Alps, Wisconsin - in North America.
The moving glacier changed the relief of the underlying surface. The degree of its impact was different and depended on the rocks that made up the surface, on its relief, on the thickness of the glacier. The surface, composed of soft rocks, was smoothed by the glacier, destroying sharp ledges. He destroyed fractured rocks, breaking off and carrying away their pieces. Freezing into a moving glacier from below, these pieces contributed to the destruction of the surface.

Encountering hills on the way, composed of hard rocks, the glacier polished (sometimes to a mirror shine) the slope facing towards its movement. Frozen pieces of hard rock left scars, scratches, and created complex glacial shading. The direction of ice scars can be used to judge the direction of movement of the glacier. On the opposite slope, the glacier broke out pieces of rock, destroying the slope. As a result, the hills acquired a characteristic streamlined shape. "lamb foreheads". Their length varies from several meters to several hundred meters, their height reaches 50 m. also in Canada and Scotland.
A moraine was deposited at the edge of the melting glacier. If the end of the glacier, due to melting, was delayed at a certain boundary, and the glacier continued to supply sediments, ridges and numerous hills arose. terminal moraines. Moraine ridges on the plain often formed near protrusions of the subglacial bedrock relief. Ridges of terminal moraines reach a length of hundreds of kilometers at a height of up to 70 m. Sometimes they are located parallel to each other. The depressions separating the uplands in the region of the terminal moraine are often occupied by swamps and lakes. A striking example of a terminal moraine ridge is Salpausselska (Finland). When advancing, the glacier moves the terminal moraine deposited by it and loose deposits in front of it, creating pressure moraine- wide asymmetric ridges (steep slope facing the glacier). Many scientists believe that most of the terminal moraine ridges were created by the pressure of the glacier.
When the glacier body melts, the moraine contained in it is projected onto the underlying surface, greatly softening its irregularities and creating a relief. main moraine. This relief, which is a flat or hilly plain with swamps and lakes, is characteristic of the areas of ancient continental glaciation.
In the area of ​​the main moraine one can see drumlins- oblong hills, elongated in the direction of movement of the glacier. The slope facing towards the moving glacier is steep. The length of drumlins ranges from 400 to 1000 m, width - from 150 to 200 m, height - from 10 to 40 m. Drumlins are located in groups in the peripheral glaciation area, on the plain or in the foothill areas. From the surface, they are composed of moraine, enveloping a core of bedrock deposits or deposits of meltwater flows. Their origin is still unclear. It is assumed that the moraine, frozen into the bottom of the glacier, lingered at the elevations of the glacial bed, increasing them. dimensions, and the glacier gave them a smoothed shape.
On the territory of Russia, drumlins exist in Estonia, on the Kola Peninsula, in Karelia and in some other places. They are found, also in Ireland, in North America.
The water flows that occur during the melting of the glacier wash out and carry away mineral particles, depositing them where the flow slows down. With the accumulation of deposits of melt water, strata of loose sediments arise, which differ from moraine in the sorting of the material. The landforms created by meltwater flows both as a result of erosion and sediment accumulation are very diverse.
Ancient runoff valleys melted glacial waters - wide (from 3 to 25 km) hollows stretching along the edge of the glacier and crossing the pre-glacial river valleys and their watersheds. Deposits of glacial waters filled these hollows. Modern rivers partially use them and often flow in disproportionately wide valleys.
Ancient valleys can be observed on the territory of Russia (the Baltic States, Ukraine), Poland, Germany.
Kamy - rounded or oblong hills with flat tops and gentle slopes, outwardly resembling moraine hills. Their height is 6-12 m (rarely up to 30 m). The depressions between the hills are occupied by swamps and lakes. Kames are located near the glacier boundary, on its inner side, and usually form groups, creating a characteristic kame relief.
Kams, in contrast to moraine hills, are composed of roughly sorted material. The varied composition of these deposits and especially the thin clays found among them suggest that they accumulated in small lakes that arose on the surface of the glacier. During the melting of the glacier, the accumulated deposits were projected onto the surface of the main moraine. The question of the formation of kams is not yet clear.
The thawing of individual blocks of dead ice hidden in the deposits of glacial waters explains the origin of glacial baths (zolls) - relatively small rounded depressions (diameter - several tens of meters, depth - several meters). Glacial baths are also found in areas of permafrost.
Oz- ridges resembling railway embankments. The length of the lakes is measured in tens of kilometers (30-40 km), the width - in tens (rarely hundreds) of meters, the height is very different: from 5 to 60 m. The slopes are usually symmetrical, steep (up to 40 °).
The eskers extend independently of the modern terrain, often crossing river valleys, lakes, and watersheds. Sometimes they branch, forming systems of ridges, which can be divided into separate hills. The eskers are composed of diagonally stratified and, more rarely, horizontally stratified deposits: sand, gravel, and pebbles.
The origin of the eskers can be explained by the accumulation of sediments carried by meltwater flows in their channels, as well as in cracks inside the glacier. When the glacier melted, these deposits were projected onto the surface.
Zander- spaces adjacent to the terminal moraines, covered with deposition of melt water (washed moraine). At the end of the valley glaciers, sandra are insignificant in area, composed of medium-sized rubble and poorly rounded pebbles. At the edge of the ice cover on the plain, they occupy large spaces, forming a wide strip of outwash plains. Outwash plains are composed of vast flat fans of subglacial flows that merge and partially overlap each other. On the surface of the outwash plains, landforms created by the wind often appear.
An example of outwash plains can be a strip of "woodlands" on the Russian Plain (Pripyat, Meshcherskaya).

In areas that have experienced glaciation, there is a certain regularity in the distribution of the relief, its zoning(Fig. 111). In the central part of the glaciation area (Baltic Shield, Canadian Shield), where the glacier arose earlier, persisted longer, had the greatest power and speed of movement, an erosional glacial relief was formed. The glacier demolished pre-glacial loose deposits and had a destructive effect on the bedrock (crystalline) rocks, the degree of which depended on the nature of the rocks and the pre-glacial relief. The cover of a thin moraine, which lay on the surface during the retreat of the glacier, did not obscure the features of its relief, but only softened them. The accumulation of moraine in deep depressions reaches 150–200 m, while there is no moraine in neighboring areas with bedrock projections.
In the peripheral part of the glaciation area, glaciation existed for a shorter time, had less power and slower movement. The latter is explained by a decrease in head with distance from the glacier feeding center and its congestion with clastic material. In this part, the glacier was mainly unloaded from clastic material and created accumulative landforms.
Outside the border of the glacier distribution, directly adjoining it, there is a zone, the features of the relief of which are associated with the erosive and accumulative activity of melted glacial waters. The cooling effect of the glacier also affected the formation of the relief of this zone.
As a result of the repeated glaciation and spread of the glacial cover in different glacial epochs, as well as as a result of shifts in the edge of the glacier, forms of glacial relief of various origins turned out to be superimposed on each other and greatly changed.
The glacial topography of the surface freed from the glacier was affected by other exogenous factors. The earlier the glaciation was, the stronger, naturally, the processes of erosion and denudation changed the relief. At the southern boundary of maximum glaciation, the morphological features of the glacial relief are absent or have been preserved very weakly. Evidence of glaciation are the boulders brought by the glacier and the remnants of heavily altered glacial deposits preserved in places. The relief of these areas is typically erosional. The river network is well formed, the rivers flow in wide valleys and have a developed longitudinal profile. To the north of the boundary of the last glaciation, the glacial relief has retained its features and is a disorderly accumulation of hills, ridges, closed basins, often occupied by shallow lakes. Moraine lakes are relatively quickly filled with sediment, often they are drained by rivers. The formation of the river system at the expense of lakes "strung" by the river is typical for areas with glacial relief. Where the glacier has lasted the longest, the glacial relief has changed comparatively little. These areas are characterized by a river network that has not yet been completely formed, an undeveloped river profile, and lakes “not drained” by rivers.