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The results of 100-year-long observations of the glacial geosystem dynamics in the Munku-Sardyk massif
Geography and Natural Resources 30 (2009) 272–278
The results of 100-year-long observations of the glacial geosystem dynamics in the Munku-Sardyk massif A. D. Kitov a , S. N. Kovalenko b and V. M. Plyusnin a, * Institute of Geography SB RAS, Irkutsk Irkutsk State Pedagogical University, Irkutsk a
b
Received 10 December 2008
Abstract Using the glaciers of the Munku-Sardyk massif as an example, we examine the patterns of changes of glaciological landscapes as revealed through instrumental observations. We present the quantitative parameters of the dynamics of nival-glacial geosystems obtained by using state-of-the-art remote sensing and GIS analysis facilities. Interesting new features reflecting the state of geosystems are described, and particularizing geoinformation calculations and a mapping are performed for a subsequent monitoring of their state. Keywords: geosystems, glaciers, Eastern Sayan, dynamics, instrumental observations, GIS technologies.
Introduction The highest summit of the Eastern Sayan mountains is Mt. Munku-Sardyk (3491 m above the sea level); it is called by the aboriginal population the “Eternally White Golets”, and the surrounding mountain landscapes have attracted for a long time the attention of explorers and travelers. A century has elapsed since the institution of monitoring observations of nival-glacial geosystems based on acquiring instrumental data. Several periods are identifiable in the history of observations of this mountain massif. The first of them involves evidence for the occurrence of glaciers in the massif from the year 1859 [1], the second period is associated with the conquering of the summit and the quantitative description of the glaciers due to S. P. Peretolchin as well as with the publication of the results in 1908 [2], the third period corresponds to E. V. Maksimov’s exploration [3] (in the mid-20th century) which extended the description of geosystems, and the fourth period has to do with the research done by V. E. Arefiev and R. M. Mukhametov (during the 1980s) [4] based on using refining phototheodolite survey. And, finally, the modern period that began in the 21st century; it is characterized by investigations made with GPS instruments, remotely sensed satellite data, and by the continuation of regular observations on the Munku-Sardyk massif during
* Corresponding author. E-mail address: [email protected] (V. M. Plyusnin)
2006–2008 by staff members of the V. B. Sochava Institute of Geography SB RAS and the Irkutsk State Pedagogical University [5–7]. The relative accessibility of the Munku-Sardyk massif, the results of field descriptions accumulated for 100 years, and the new glacial formations as discovered by our expeditions permit this area to be considered a unique key site as regards the possibility of revealing the development tendencies of mountain and nival-glacial geosystems and building reconstructive and predictive models of the development of mountain landscapes under the conditions of the ever-increasing anthropogenic pressures. Objects and methods of investigation Physicogeographically, the Munku-Sardyk mountain massif refers to the Southern-Siberian mountainous region, the Oka-Tunka mountain-taiga-golets province, and to the Kitoi-Tunka golets-high mountain district [8]. The middle part of the massif is represented by alpine-type systems of castellated ridged watersheds with pointed peaks with abs. alt. 3400 m or more, separated by numerous cirques, often with lakes in their bottoms. The valleys of the contemporary rivers of the massif (Bely Irkut, Muguvek, Bugovek, Sredny Irkut, and others) represent stepped troughs [5]. Their bottoms bear evidence of former glacial activity in the form of “roches moutonnées”, and parallel ridges of moraines; sometimes there occur lateral moraines leaning upon the valley slopes and clearly pronounced in the relief. The steeply
Copyright © 2009 IG SB, Siberian Branch of RAS. Published by Elsevier B.V. All rights reserved doi:10.1016/j.gnr.2009.09.012
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sloping rocky sides of troughs and cirques, with cones and aprons of taluses and screes were formed by glacial processes, and by the contemporary gravitational slope processes. The periglacial spurs lowering along the southern and northern direction from the mountain range’s axis below 3000 m become subdued, which is the result of the activity of cryogenic processes. Numerous scours, gullies, and narrow pebble-laden river channels, often squeezed tightly within gorges between cliffs, constitute the water-erosion component of the relief. Geologically, the territory has not been adequately explored. There is only one geological map at a scale of 1:200 000 as compiled in 1961 [9] with the explanatory note [10] as well as a few scientific publications offering rather meager information on this area [11, 12]. According to the cited references and to our observations, the study area has a relatively simple structure. Its western, orographically highest half is occupied by Mid-Paleozoic igneous granitoid rocks comprising our identified alimentation region of ancient and contemporary glaciers. This complex on the geological map is referred to as the Munku-Sardyk complex and consists of quartz diorites, plagioclase granites and granodiorites, microcline granites and granosyenites as well as of granite porphyries. The eastern, lower part of the area is composed by Ordovician sedimentary, weakly metamorphized rocks; the territory represents a drainage and transit region for the glaciers in the past as well as a region of intense contemporary water erosion. The southern and northern slopes of the massif distinctly differ. The southern slopes that are located on the territory of Mongolia are more gentle in their summit part, and the troughs further out often come abruptly to an end and, in the form of a gentle ramp, extend 10–15 km toward the depression of Lake Hovsgol. The cirques of this side of the mountain range represent shallow graded hollows with almost no traces of moraines of modern glaciation. The glaciers occurring on the southern slope of the Munku-Sardyk massif are relatively gently sloping, show virtually no activity and are oriented along the southward and southeastward directions. In this area, we identified and described three glaciers with exposed ice, and one rock glacier. The northern slope, located on the territory of Russia, is, on the contrary, steep and is largely represented by sheer rock walls which are hazardous because of constantly recurring rockfalls, taluses, avalanches, and debris flows. The spurs are shorted when compared with the southern slope and are directed toward the area’s main artery, the Irkut river. This area clearly shows the results of glacial (ancient as well as modern) activity, which confirms the stepped pattern of the slope. The bottoms of the cirques end with lakes or a cascade of them. Contemporary glaciers are hanging glaciers, they are active and oriented along a northern direction. The indicator of contemporary glaciation in the mountains is provided by the altitudinal location of the lower level of chionosphere above which the annual number of days with snow cover reaches 365, i.e. the altitude where, with an
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increase in the abundance of snow or at the time of climate cooling, formation of glaciers is possible. For the MunkuSardyk mountain massif this indicator is 3550 m [3] and, according to data reported by S. P. Peretolchin, 3050 m [2]. In real situations, however, glaciers are generated below this level because of snowstorm- and avalanche-caused accumulation of snow in the cirques and on the shadowed slopes of the valleys. In the Eastern-Sayan mountains, nival-glacial geosystems are represented by glaciers, perennial snow patches, overflow ice (icings), and rock glaciers. The glaciers in this area are formed by relatively abundant solid precipitation, and by subzero temperatures. According to the morphological type, cirque glaciers predominate. This type of glaciers includes also the glaciers of the Munku-Sardyk under investigation. During 2002–2008 the field expeditions to the area of this mountain massif collected ice samples, carried out the descriptions of the relief and vegetation, and found (July 2006) the minimum thermometer installed by S. P. Peretolchin in 1900. In 2008, samples were taken of remains of Siberian larch buried under loose debris material which grew previously above the contemporary forest limit. The satellite navigation GPS receiver was used in making measurements of the boundaries and absolute altitudes of five glaciers: the Southern and Northern Peretolchin, Radde, Babochka and Pogranichny glaciers (Fig. 1). The measurement results and contemporary characteristics of the glaciers are provided in Tables 1 and 2. The open surface lengths of the glaciers were calculated from data on altitude boundaries (top-bottom), and from the extent in plan on the map or on the space-acquired image. The morainic deposit-free surface area of the glaciers was determined by mans of the 3D-tools of the ArcView GIS package.
Fig. 1. A portion of the map of contemporaneous glaciation of the Munku-Sardyk massif. 1 – contemporary glaciers; 2 – lakes; 3 – altitude figures and summit names; 4 – contour lines run out every 40 m; 5 – streams.
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Table 1 General characteristics of open parts of glaciers Data of S. P. Peretolchin (1908) [2]
Parameter
Data of E. V. Maksimov (1963) [3]
Contemporaneous data, August 2008
Southern Peretolchin glacier on the territory of the MPR Ice area, km
2
Lower boundary above sea level, m Length, m
0.4
–
0.17
3173
–
3215
–
–
575
Northern Peretolchin glacier on the territory of Russia Ice area, km2
0.68
–
0.53
Lower boundary above sea level, m
2776
2908
2935
Length, m
1503
–
1072
0.3
0.3–0.4
0.28
Lower boundary above sea level, m
2800
2830
2805
Length, m
600
600
840
–
0.0187
Radde glacier on the territory of Russia Ice area, km2
Babochka glacier on the territory of the MPR –
Ice area, km2 Lower boundary above sea level, m
–
–
2884
Length, m
–
–
245
Glacier at the Pogranichny peak on the territory of the MPR Ice area, km2
–
–
0.181
Lower boundary above sea level, m
–
–
3068
Length, m
–
–
657
Buried glacier in the valley а the Zhokhoi river (not detected by us) Ice area, km2 Lower boundary above sea level, m Length, m
0.3
–
–
2800
2600
–
–
1500
–
Note. «–» – data not available. Table 2 Morphological characteristics of the open surface of the glaciers of the Munku-Sardyk massif
Glacier name
Upper boundary
Lower boundary
Height
above sea level, m
Length in map projection
Length of surface
Area of surface
m
Area in map projection km2
Southern Peretolchin
3425
3215
210
535
574.74
0.1659
0.1506
Northern Peretolchin
3485
2935
577
920
1071.87
0.5284
0.4428
Radde
3120
2796
324
775
840.0
0.2846
0.2439
Babochka
2890
2884
6
245
245.07
0.0187
0.0171
Pogranichny
3380
3068
312
578
656.83
0.1807
0.1516
Glacial objects of the Munku-Sardyk mountain massif The Northern Peretolchin glacier is the largest of the family of glaciers of this mountain massif. It is located on the northern slope of the main mountain range (the territory of Russia). This glacier was most thoroughly studied by all
investigators of the Munku-Sardyk. In terms of its outward appearance, it is recognized as the most typical cirque glacier with active processes of formation of terminal moraines. According to observations reported by E. V. Maksimov [3], it is not as stable as the similar northern Radde glacier, although it is younger than the Radde glacier. Early in its existence the
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open part of the glacier had two glacial lobes flowing round the “Faraon” riegel, and they were lower by more than 100 m than their contemporary position. Only a part of the righthand lobe has remained open to date, but the ends of the lobes, covered in rock fragments, persist at the same level. Since the glacier is considerably steep (up to 50°) and is constantly experiencing rockfall taluses, the amount of arriving debris material is large, and the formation of the contemporary terminal moraine is significant. The glacier shows a host of cracks and glacial drainage channels. In 2006 and, especially, in 2008, an intensification of the ablation processes and subsidence of morainic material along the glacial drainage channel caused outcropping of the buried ice in the debris-clad parts of the right-hand as well as left-hand glacial lobes. The open surface of the glacier is the home of active growth of algae, which was pointed out by all investigators. Based on the readings of the minimum thermometer (оС), installed in 1900 by S. P. Peretolchin, the temperature regime has remained virtually unchanged for 100 years. 1900/1901
1901/1902
1902/1903
1903/1904
1904/1905
1905/1906
–36.0
–35.5
–33.5
–35.5
–32.4
–35.0
1906/1907
1907-1937
1937-1940
2006/2007
2007/2008
–34.2
–44.5
–49.5
–31.5
–34.2
The Southern Peretolchin glacier is located on the territory of the Mongolian People’s Republic (MPR); it is more gently sloping (with a steepness of 40о) when compared with the Northern glacier. In recent years its summit part has virtually not merged together with the Northern glacier. The glacier does not show any hazardous rockfalls. We managed to outline the glacier on the map by means of the GPS receiver. Its outline coincided with the image based on QuickBird ultrahigh-resolution remote sensing data. The glacier shows a great number of shallow (0.5–1 m) scours. The lower part of the open ice flattens out to become a nearly horizontal surface and changes to a rock glacier with small moraines shaped as humpies up to 3 m in height, and 20 m in diameter. The Radde glacier is located on the territory of Russia, at the Bely Irkut riverhead. It descends from the crest of the mountain range northward into a narrow trough valley. The area and length of the open ice in a completely filled-up cirque are 0.28 km2 and 0.84 km, respectively. Unlike the Peretolchin glacier, the open part of which has the largest steepness in its upper part, the Radde glacier smoothly flows down the crest; after that, it steeply (up to 40°) comes down the riegel to the trough valley where it is actually overlapped by morainic large-block material (up to 5–10 m across) composed by granitoid rock fragments. Morainic deposits extend well beyond the open part of the glacier and steeply terminate above a next step. During rainy weather, the open part of the glacier imposes severe hazards upon people because of the constant occurrence of rockfalls. It is the most stable glacier of the mountain massif.
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The Babochka glacier is located on the territory of Mongolia, in the southeastern cirque of the southern arm of the main mountain range. The glacier is far and away the smallest in area (see Tables 1 and 2) and heavily graded, but the movement of the ice facilitates transportation of fragmented rock to generate the terminal moraine. Its continuation, overlapped by layers of ancient and modern moraines, represents a hummocky convex field eaten by sinkholes and extended crevasses exposing formations of buried ice on the bottom. We discovered this glacier in 2007 and investigated it in greater detail in 2008. Although it is located in the upper part of the cirque, it resembles a valley glacier because of its weak gradient of slope and its very small height (6 m). The glacier at the Pogranichny Peak is also located in Mongolia and remains virtually unexplored. It is typical cirque-type hanging glacier oriented along a southeastern direction. At the time of our observations, it did not show any severe rockfalls. Similar to the Southern Peretolchin glacier, it precipitates itself with its high step in the relief into the valley of the tributary of Lake Hovsgol. The lower part of the glacier distinctly shows a riegel shaped like a flattened “roche moutonnée”, and hence the glacier breaks down into two lobes. As is the case with the other glaciers in the area, its lower part exhibits a mobile rock glacier, and because of the sharp steep escarpment, the relief does not create any favorable conditions for formation of terminal moraines. Unlike the Southern Peretolchin glacier which is concave along the center line, this glacier is a convex one. The other glacial objects in the area of this mountain massif are represented by icing phenomena. First and foremost there are two large clearly identifiable icings within deep near-channel incisions of the idle parts of the Muguvek and Bely Irkut rivers as well as in the lower reaches and mouths of these rivers. Furthermore, icings are produced along the channel of the Ledyanoi creek in its lower reaches, and on several lateral tributaries of the Muguvek and Bely Irkut. During the period of observation of these glacial formations from 2002 to 2008, instrumental measurements were made of their area, thickness and dynamics of occurrence. As the investigations showed, the development intensity of icings decreased substantially during the aforementioned years. While as early as 2005, in the lower reaches of the Bely Irkut river there still persisted icings till the end of June and a cross-country vehicle traveling on such icings in May could reach the spit of the Muguvek and Bely Irkut rivers, some stretches of them exposed in 2007–2008 pebble-clad riverbed, so that the route became impassable. On the creeks flowing into the Bely Irkut, the thickness of icings decreased by about 2 m. Discussion During 2002–2008, we studied the glaciers of the MunkuSardyk mountain massif, on its northern and southern sides. Their minimum and maximum elevations are 2805 and 3485 m, whereas the summits of the cirque walls reach 3490 m.
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The glaciers are small in size. In the winter they are fed by atmospheric precipitation, avalanches, and blizzard-induced snow sweeping off. We look in the Southern and Northern Peretolchin glaciers in the greatest detail. According to current remotely sensed data, the mountains show glaciers that are missing on topographic maps; on the other hand, the presence of previously reported glaciers is sometimes not confirmed. Thus, topographic and tourist maps at scales smaller than 1:50 000 display a glacier on the southwestern slope of the main summit of the Munku-Sardyk. However, the schematic map of S. P. Peretolchin [2] shows only the Southern and Northern glaciers but do not indicate the glaciation of the southwestern slopes. A portion of the contemporary tourist map, however, shows the existing glaciers as well as the erroneously included glaciers (Fig. 2).
Measurements showed that the lower part of the open ice of the Northern Peretolchin glacier is currently at an altitude of 2935 m above the sea level. A comparison with earlier data revealed that the lower boundary of the open part of the glacier in 2006 was 132 m higher than in 1906, by 38 m higher than in 1963, and by 86 m higher than in 1982. The movement of the open part of the glacier, recorded in 1982, was associated with a cooling during 1960–1970 which enhanced the transport activity of the glacier. On the whole, however, there is a correlation with a climate warming, as the firn portion of the Peretolchin glacier is gradually reducing its size. Nevertheless, the bulk of the glacier is changing less distinctly – only its lower edge gradually changes to a rock glacier, lateral moraines are traceable within 180 m, and the
Fig. 2. The maps of the glaciers of the Munku-Sardyk massif. а – schematic map by S. P. Peretolchin (1908); b – a portion of the contemporaneous tourist map “Munku-Sardyk – An Eternally White Golets” (2003). 1 – the Northern and Southern glaciers according to S. P. Peretolchin’s schematic map; 2 – glaciers on the contemporaneous tourist map; 3 – screes and taluses; 4 – lakes; 5 – altitude figures and summit names; 6 – principal summit of the Munku-Sardyk; 7 – passes and their numbers; 8 – contour lines run out every 40 m; 9 – streams; 10 – state border.
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bank of the terminal moraine reaches a height of 39 m. The movement of the glacier is suggested by transverse cracks in the open part of the ice up to 25 m long and up to 6 m deep, as well as the numerous transverse and diagonal subsidence cracks in the lower part. The southern glaciers in their lower part steeply precipitate into the gorge, and this does not create favorable conditions for formation of distinct terminal moraines. In the summer time, especially in foul weather, the Peretolchin glacier is hazardous because of its frequently occurring rockfalls (according to our observations, rockfalls recur at intervals of 15–20 min). The state of firn snow changes dramatically with climatic conditions of a year. Sometimes it is a sinter ice but more often a solid firn. In the summer of 2006, we discovered sinks in the terminal moraine which exposed the buried body of the glacier. In the warmer year of 2008, within the righthand lobe there emerged a further three such sinks, while the former sinks became significantly deeper. A study of these ice caves showed that the glacier actually did not decrease its length, but the lobe more than 100 m in length developed a stony jacket 1–1.5 m in thickness which gradually changed to a morainic bank. The fact that the site of emergence of the glacial flow from beneath the moraine changes every year also confirms the existence of a rock glacier. Recent years witnessed an abrupt warming and, accordingly, distinct changes of glacial-nival objects. Glaciers in their terminal part, without reducing in length, transform to rock glaciers, and the visible lower boundary of the glacier increased in height (by 17 m during 2006–2008 as evidence by GPS measurements). In the summit part, there was an increase of the gap between the Northern and Southern glaciers. Icings decay substantially toward the autumn, decreasing in height (compared with the old marks on tree stems) by about 2 m. The number and thickness of perennial snow patches decreased. There is taking place an encroachment of forest geosystems into mountain-tundra geosystems manifesting itself as the appearance of separate undersized larch trees (1–2 m) above the contemporary forest limit. On the other hand, some stems of dead trees that were detected on the morainic slope in the valley of the Bugovek river suggest that previously (perhaps in the Holocene) trees grew above the contemporary upper forest limit. The preserved stumps of larch trees are 1 m in diameter and presumably 250 years old. Results of radiocarbon analysis of wood samples would be instrumental in drawing the more accurate conclusions about the changes of climate in that historical period. It will be possible to refine the boundaries of the mountain geosystems and their genetic links through the use of the landscape map for the Munku-Sardyk massif whose compilation was started on the basis of remotely sensed data. Conclusion For the last 100 years the annual values of the positive trend of air temperatures have been 0.2–0.5 °С averaged
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over 10 years [13]. This leads to the northward displacement of the permafrost line, the rise of the upper forest limit in the mountains, the retreat of glaciers and their transformation to rock glaciers, and to a decrease in the area of golets (Alpine rocks). Structural transformation of geosystems is favored not only by a rise of air temperature but also by regional changes in humidification as well as by local anthropogenic impacts. Phenomena of this kind were recorded across the extended territories of Siberia, Northern Mongolia and Northwestern China [6, 7] and suggest the conclusion that these processes are fairly peculiar to local glaciological systems [14, 15]. Genetically, the rock glaciers occurring at the trough valley heads represent continuations of existing glaciers produced by accumulation of fragmented rock which is transported by this same glacier and fill up its lower part. At periods of warming, moraines and intermontane depressions develop thawed patches exposing the buried ice of the glacier. With a further development of the process of warming in the mountains in Eurasia deep inland, distinctive changes should be expected to occur in the established structure of geosystems: the mountain-forest, mountain-steppe, golets, mountain-tundra and nival-glacial geosystems. Investigations in key areas will offer a means of determining the trend of these changes and to create the quantitative information base for the dynamics of mountain geosystems. It would be of great interest to determine quantitative data on the movement of glacier snouts for given time intervals and on the development dynamics of the overflow ice, identify buried glaciers, and to compile the landscape map for the mountain massif with the use of state-of-the-art GIS technologies, navigation-topographic instruments and information obtained through remote sensing of the Earth. Using the latest remotely sensed data and GIS instrumentation we generated the maps for the surfaces of glaciers, and their steepness and relief pattern, which adds to and enhances, at the new information and time-efficiency level, our knowledge of mountain landscapes and glaciological processes not easily accessible on the globe. References 1. The History of the Semi-Centennial Activity of the Imperial Russian Geographical Society. 1845–1895. SPb, 1896, 468 p. 2. Peretolchin S. P. The glaciers of the Munku-Sardyk Range. Izv. Tomsk. tekhn. in-ta, 1908, v. 9, pp. 1–47. 3. Maksimov E. V. Concerning the glaciers of the Munku-Sardyk massif in the Eastern Sayan mountains. Izv. VGO, 1965, v. 97, issue 2, pp. 176–180. 4. Arefiev V. and Mukhametov R. On the Glaciers of the Altai and Sayan Mountains. Barnaul, 1996, 176 p. 5. Kitov A. D., Kovalenko S. N. and Drozdova O. V. Some details of the use of state-of-the-art methods of analyzing the MunkuSardyk landscapes. Proc. 13th Scient. Meeting of Geographers of Siberia and the Far East Commemorating the 50th Anniversary of the Institute of Geography SB RAS (Irkutsk, 27–29 No-
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vember 2007). Irkutsk: Institute of Geography SB RAS Publisher, 2007, v. 1, pp. 141–142. Plyusnin V. M., Drozdova O. V., Kitov A. D., and Kovalenko S. N. The dynamics of the mountain geosystems of southern Siberia. Geografiya i prirod. resursy, 2008, No. 2, pp. 5–13. Kitov A. D. and Plyusnin V. M. Features of local glaciological phenomena in mountain landscapes (exemplified by the Baikal-Urumchi transect). In: Sustainable Development of Territories: GIS Theory and Practical Experience: proc. Intern. Conf. InterCarto-InterGIS–14, Saratov–Urumchi, 24–26 June 2008. Saratov: International Cartographic Association, 2008, v. 1, pp. 130–137. Atlas of Lake Hovsgol. Moscow: GUGK, 1989, 118 p. Geological Map of the USSR. М–47–V. Ser. Eastern Sayan. Sc. 1:200 000. Author and compiler V. P. Arsentiev. Moscow: MINGEO SSSR, 1961, 1 sheet. Explanatory Note to the Geological Map of the USSR at a Scale
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of 1:200 000. М–47–V. Ser. Eastern Sayan. Moscow: Gosgeoltekhizdat, 1962, 56 p. The Evolution of the Earth’s Crust in the Pre-Cambrian and Palaeozoic (Sayan-Baikal Mountainous Region). Belichenko V. G., Shmotov A. P., Sezko A. I. et al. Novosibirsk: Nauka, 1988, 161 p. Lodochnikov V. N. The petrology of the Ilchiro-Mondinsky District. Trudy Vost.-Sib. geologoupravleniya, 1941, issue 28, 197 p. Gustokashina N. N. Long-Term Changes of the Main Elements of Climate on the Territory of the Baikal Region. Irkutsk: Institute of Geography SB RAS Publisher, 2003, 107 p. Plyusnin V. M. Landscape Analysis of Mountain Territories. Irkutsk, 2003, 257 p. Plyusnin V. M. Response of inland mountain systems to global climate change. Geografiya i prirod. resursy, 2007, No. 3, pp. 67–74.
The results of 100-year-long observations of the glacial geosystem dynamics in the Munku-Sardyk massif A. D. Kitov a , S. N. Kovalenko b and V. M. Plyusnin a, * Institute of Geography SB RAS, Irkutsk Irkutsk State Pedagogical University, Irkutsk a
b
Received 10 December 2008
Abstract Using the glaciers of the Munku-Sardyk massif as an example, we examine the patterns of changes of glaciological landscapes as revealed through instrumental observations. We present the quantitative parameters of the dynamics of nival-glacial geosystems obtained by using state-of-the-art remote sensing and GIS analysis facilities. Interesting new features reflecting the state of geosystems are described, and particularizing geoinformation calculations and a mapping are performed for a subsequent monitoring of their state. Keywords: geosystems, glaciers, Eastern Sayan, dynamics, instrumental observations, GIS technologies.
Introduction The highest summit of the Eastern Sayan mountains is Mt. Munku-Sardyk (3491 m above the sea level); it is called by the aboriginal population the “Eternally White Golets”, and the surrounding mountain landscapes have attracted for a long time the attention of explorers and travelers. A century has elapsed since the institution of monitoring observations of nival-glacial geosystems based on acquiring instrumental data. Several periods are identifiable in the history of observations of this mountain massif. The first of them involves evidence for the occurrence of glaciers in the massif from the year 1859 [1], the second period is associated with the conquering of the summit and the quantitative description of the glaciers due to S. P. Peretolchin as well as with the publication of the results in 1908 [2], the third period corresponds to E. V. Maksimov’s exploration [3] (in the mid-20th century) which extended the description of geosystems, and the fourth period has to do with the research done by V. E. Arefiev and R. M. Mukhametov (during the 1980s) [4] based on using refining phototheodolite survey. And, finally, the modern period that began in the 21st century; it is characterized by investigations made with GPS instruments, remotely sensed satellite data, and by the continuation of regular observations on the Munku-Sardyk massif during
* Corresponding author. E-mail address: [email protected] (V. M. Plyusnin)
2006–2008 by staff members of the V. B. Sochava Institute of Geography SB RAS and the Irkutsk State Pedagogical University [5–7]. The relative accessibility of the Munku-Sardyk massif, the results of field descriptions accumulated for 100 years, and the new glacial formations as discovered by our expeditions permit this area to be considered a unique key site as regards the possibility of revealing the development tendencies of mountain and nival-glacial geosystems and building reconstructive and predictive models of the development of mountain landscapes under the conditions of the ever-increasing anthropogenic pressures. Objects and methods of investigation Physicogeographically, the Munku-Sardyk mountain massif refers to the Southern-Siberian mountainous region, the Oka-Tunka mountain-taiga-golets province, and to the Kitoi-Tunka golets-high mountain district [8]. The middle part of the massif is represented by alpine-type systems of castellated ridged watersheds with pointed peaks with abs. alt. 3400 m or more, separated by numerous cirques, often with lakes in their bottoms. The valleys of the contemporary rivers of the massif (Bely Irkut, Muguvek, Bugovek, Sredny Irkut, and others) represent stepped troughs [5]. Their bottoms bear evidence of former glacial activity in the form of “roches moutonnées”, and parallel ridges of moraines; sometimes there occur lateral moraines leaning upon the valley slopes and clearly pronounced in the relief. The steeply
Copyright © 2009 IG SB, Siberian Branch of RAS. Published by Elsevier B.V. All rights reserved doi:10.1016/j.gnr.2009.09.012
A.D. Kitov et al. / Geography and Natural Resources 30 (2009) 272–278
sloping rocky sides of troughs and cirques, with cones and aprons of taluses and screes were formed by glacial processes, and by the contemporary gravitational slope processes. The periglacial spurs lowering along the southern and northern direction from the mountain range’s axis below 3000 m become subdued, which is the result of the activity of cryogenic processes. Numerous scours, gullies, and narrow pebble-laden river channels, often squeezed tightly within gorges between cliffs, constitute the water-erosion component of the relief. Geologically, the territory has not been adequately explored. There is only one geological map at a scale of 1:200 000 as compiled in 1961 [9] with the explanatory note [10] as well as a few scientific publications offering rather meager information on this area [11, 12]. According to the cited references and to our observations, the study area has a relatively simple structure. Its western, orographically highest half is occupied by Mid-Paleozoic igneous granitoid rocks comprising our identified alimentation region of ancient and contemporary glaciers. This complex on the geological map is referred to as the Munku-Sardyk complex and consists of quartz diorites, plagioclase granites and granodiorites, microcline granites and granosyenites as well as of granite porphyries. The eastern, lower part of the area is composed by Ordovician sedimentary, weakly metamorphized rocks; the territory represents a drainage and transit region for the glaciers in the past as well as a region of intense contemporary water erosion. The southern and northern slopes of the massif distinctly differ. The southern slopes that are located on the territory of Mongolia are more gentle in their summit part, and the troughs further out often come abruptly to an end and, in the form of a gentle ramp, extend 10–15 km toward the depression of Lake Hovsgol. The cirques of this side of the mountain range represent shallow graded hollows with almost no traces of moraines of modern glaciation. The glaciers occurring on the southern slope of the Munku-Sardyk massif are relatively gently sloping, show virtually no activity and are oriented along the southward and southeastward directions. In this area, we identified and described three glaciers with exposed ice, and one rock glacier. The northern slope, located on the territory of Russia, is, on the contrary, steep and is largely represented by sheer rock walls which are hazardous because of constantly recurring rockfalls, taluses, avalanches, and debris flows. The spurs are shorted when compared with the southern slope and are directed toward the area’s main artery, the Irkut river. This area clearly shows the results of glacial (ancient as well as modern) activity, which confirms the stepped pattern of the slope. The bottoms of the cirques end with lakes or a cascade of them. Contemporary glaciers are hanging glaciers, they are active and oriented along a northern direction. The indicator of contemporary glaciation in the mountains is provided by the altitudinal location of the lower level of chionosphere above which the annual number of days with snow cover reaches 365, i.e. the altitude where, with an
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increase in the abundance of snow or at the time of climate cooling, formation of glaciers is possible. For the MunkuSardyk mountain massif this indicator is 3550 m [3] and, according to data reported by S. P. Peretolchin, 3050 m [2]. In real situations, however, glaciers are generated below this level because of snowstorm- and avalanche-caused accumulation of snow in the cirques and on the shadowed slopes of the valleys. In the Eastern-Sayan mountains, nival-glacial geosystems are represented by glaciers, perennial snow patches, overflow ice (icings), and rock glaciers. The glaciers in this area are formed by relatively abundant solid precipitation, and by subzero temperatures. According to the morphological type, cirque glaciers predominate. This type of glaciers includes also the glaciers of the Munku-Sardyk under investigation. During 2002–2008 the field expeditions to the area of this mountain massif collected ice samples, carried out the descriptions of the relief and vegetation, and found (July 2006) the minimum thermometer installed by S. P. Peretolchin in 1900. In 2008, samples were taken of remains of Siberian larch buried under loose debris material which grew previously above the contemporary forest limit. The satellite navigation GPS receiver was used in making measurements of the boundaries and absolute altitudes of five glaciers: the Southern and Northern Peretolchin, Radde, Babochka and Pogranichny glaciers (Fig. 1). The measurement results and contemporary characteristics of the glaciers are provided in Tables 1 and 2. The open surface lengths of the glaciers were calculated from data on altitude boundaries (top-bottom), and from the extent in plan on the map or on the space-acquired image. The morainic deposit-free surface area of the glaciers was determined by mans of the 3D-tools of the ArcView GIS package.
Fig. 1. A portion of the map of contemporaneous glaciation of the Munku-Sardyk massif. 1 – contemporary glaciers; 2 – lakes; 3 – altitude figures and summit names; 4 – contour lines run out every 40 m; 5 – streams.
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Table 1 General characteristics of open parts of glaciers Data of S. P. Peretolchin (1908) [2]
Parameter
Data of E. V. Maksimov (1963) [3]
Contemporaneous data, August 2008
Southern Peretolchin glacier on the territory of the MPR Ice area, km
2
Lower boundary above sea level, m Length, m
0.4
–
0.17
3173
–
3215
–
–
575
Northern Peretolchin glacier on the territory of Russia Ice area, km2
0.68
–
0.53
Lower boundary above sea level, m
2776
2908
2935
Length, m
1503
–
1072
0.3
0.3–0.4
0.28
Lower boundary above sea level, m
2800
2830
2805
Length, m
600
600
840
–
0.0187
Radde glacier on the territory of Russia Ice area, km2
Babochka glacier on the territory of the MPR –
Ice area, km2 Lower boundary above sea level, m
–
–
2884
Length, m
–
–
245
Glacier at the Pogranichny peak on the territory of the MPR Ice area, km2
–
–
0.181
Lower boundary above sea level, m
–
–
3068
Length, m
–
–
657
Buried glacier in the valley а the Zhokhoi river (not detected by us) Ice area, km2 Lower boundary above sea level, m Length, m
0.3
–
–
2800
2600
–
–
1500
–
Note. «–» – data not available. Table 2 Morphological characteristics of the open surface of the glaciers of the Munku-Sardyk massif
Glacier name
Upper boundary
Lower boundary
Height
above sea level, m
Length in map projection
Length of surface
Area of surface
m
Area in map projection km2
Southern Peretolchin
3425
3215
210
535
574.74
0.1659
0.1506
Northern Peretolchin
3485
2935
577
920
1071.87
0.5284
0.4428
Radde
3120
2796
324
775
840.0
0.2846
0.2439
Babochka
2890
2884
6
245
245.07
0.0187
0.0171
Pogranichny
3380
3068
312
578
656.83
0.1807
0.1516
Glacial objects of the Munku-Sardyk mountain massif The Northern Peretolchin glacier is the largest of the family of glaciers of this mountain massif. It is located on the northern slope of the main mountain range (the territory of Russia). This glacier was most thoroughly studied by all
investigators of the Munku-Sardyk. In terms of its outward appearance, it is recognized as the most typical cirque glacier with active processes of formation of terminal moraines. According to observations reported by E. V. Maksimov [3], it is not as stable as the similar northern Radde glacier, although it is younger than the Radde glacier. Early in its existence the
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open part of the glacier had two glacial lobes flowing round the “Faraon” riegel, and they were lower by more than 100 m than their contemporary position. Only a part of the righthand lobe has remained open to date, but the ends of the lobes, covered in rock fragments, persist at the same level. Since the glacier is considerably steep (up to 50°) and is constantly experiencing rockfall taluses, the amount of arriving debris material is large, and the formation of the contemporary terminal moraine is significant. The glacier shows a host of cracks and glacial drainage channels. In 2006 and, especially, in 2008, an intensification of the ablation processes and subsidence of morainic material along the glacial drainage channel caused outcropping of the buried ice in the debris-clad parts of the right-hand as well as left-hand glacial lobes. The open surface of the glacier is the home of active growth of algae, which was pointed out by all investigators. Based on the readings of the minimum thermometer (оС), installed in 1900 by S. P. Peretolchin, the temperature regime has remained virtually unchanged for 100 years. 1900/1901
1901/1902
1902/1903
1903/1904
1904/1905
1905/1906
–36.0
–35.5
–33.5
–35.5
–32.4
–35.0
1906/1907
1907-1937
1937-1940
2006/2007
2007/2008
–34.2
–44.5
–49.5
–31.5
–34.2
The Southern Peretolchin glacier is located on the territory of the Mongolian People’s Republic (MPR); it is more gently sloping (with a steepness of 40о) when compared with the Northern glacier. In recent years its summit part has virtually not merged together with the Northern glacier. The glacier does not show any hazardous rockfalls. We managed to outline the glacier on the map by means of the GPS receiver. Its outline coincided with the image based on QuickBird ultrahigh-resolution remote sensing data. The glacier shows a great number of shallow (0.5–1 m) scours. The lower part of the open ice flattens out to become a nearly horizontal surface and changes to a rock glacier with small moraines shaped as humpies up to 3 m in height, and 20 m in diameter. The Radde glacier is located on the territory of Russia, at the Bely Irkut riverhead. It descends from the crest of the mountain range northward into a narrow trough valley. The area and length of the open ice in a completely filled-up cirque are 0.28 km2 and 0.84 km, respectively. Unlike the Peretolchin glacier, the open part of which has the largest steepness in its upper part, the Radde glacier smoothly flows down the crest; after that, it steeply (up to 40°) comes down the riegel to the trough valley where it is actually overlapped by morainic large-block material (up to 5–10 m across) composed by granitoid rock fragments. Morainic deposits extend well beyond the open part of the glacier and steeply terminate above a next step. During rainy weather, the open part of the glacier imposes severe hazards upon people because of the constant occurrence of rockfalls. It is the most stable glacier of the mountain massif.
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The Babochka glacier is located on the territory of Mongolia, in the southeastern cirque of the southern arm of the main mountain range. The glacier is far and away the smallest in area (see Tables 1 and 2) and heavily graded, but the movement of the ice facilitates transportation of fragmented rock to generate the terminal moraine. Its continuation, overlapped by layers of ancient and modern moraines, represents a hummocky convex field eaten by sinkholes and extended crevasses exposing formations of buried ice on the bottom. We discovered this glacier in 2007 and investigated it in greater detail in 2008. Although it is located in the upper part of the cirque, it resembles a valley glacier because of its weak gradient of slope and its very small height (6 m). The glacier at the Pogranichny Peak is also located in Mongolia and remains virtually unexplored. It is typical cirque-type hanging glacier oriented along a southeastern direction. At the time of our observations, it did not show any severe rockfalls. Similar to the Southern Peretolchin glacier, it precipitates itself with its high step in the relief into the valley of the tributary of Lake Hovsgol. The lower part of the glacier distinctly shows a riegel shaped like a flattened “roche moutonnée”, and hence the glacier breaks down into two lobes. As is the case with the other glaciers in the area, its lower part exhibits a mobile rock glacier, and because of the sharp steep escarpment, the relief does not create any favorable conditions for formation of terminal moraines. Unlike the Southern Peretolchin glacier which is concave along the center line, this glacier is a convex one. The other glacial objects in the area of this mountain massif are represented by icing phenomena. First and foremost there are two large clearly identifiable icings within deep near-channel incisions of the idle parts of the Muguvek and Bely Irkut rivers as well as in the lower reaches and mouths of these rivers. Furthermore, icings are produced along the channel of the Ledyanoi creek in its lower reaches, and on several lateral tributaries of the Muguvek and Bely Irkut. During the period of observation of these glacial formations from 2002 to 2008, instrumental measurements were made of their area, thickness and dynamics of occurrence. As the investigations showed, the development intensity of icings decreased substantially during the aforementioned years. While as early as 2005, in the lower reaches of the Bely Irkut river there still persisted icings till the end of June and a cross-country vehicle traveling on such icings in May could reach the spit of the Muguvek and Bely Irkut rivers, some stretches of them exposed in 2007–2008 pebble-clad riverbed, so that the route became impassable. On the creeks flowing into the Bely Irkut, the thickness of icings decreased by about 2 m. Discussion During 2002–2008, we studied the glaciers of the MunkuSardyk mountain massif, on its northern and southern sides. Their minimum and maximum elevations are 2805 and 3485 m, whereas the summits of the cirque walls reach 3490 m.
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The glaciers are small in size. In the winter they are fed by atmospheric precipitation, avalanches, and blizzard-induced snow sweeping off. We look in the Southern and Northern Peretolchin glaciers in the greatest detail. According to current remotely sensed data, the mountains show glaciers that are missing on topographic maps; on the other hand, the presence of previously reported glaciers is sometimes not confirmed. Thus, topographic and tourist maps at scales smaller than 1:50 000 display a glacier on the southwestern slope of the main summit of the Munku-Sardyk. However, the schematic map of S. P. Peretolchin [2] shows only the Southern and Northern glaciers but do not indicate the glaciation of the southwestern slopes. A portion of the contemporary tourist map, however, shows the existing glaciers as well as the erroneously included glaciers (Fig. 2).
Measurements showed that the lower part of the open ice of the Northern Peretolchin glacier is currently at an altitude of 2935 m above the sea level. A comparison with earlier data revealed that the lower boundary of the open part of the glacier in 2006 was 132 m higher than in 1906, by 38 m higher than in 1963, and by 86 m higher than in 1982. The movement of the open part of the glacier, recorded in 1982, was associated with a cooling during 1960–1970 which enhanced the transport activity of the glacier. On the whole, however, there is a correlation with a climate warming, as the firn portion of the Peretolchin glacier is gradually reducing its size. Nevertheless, the bulk of the glacier is changing less distinctly – only its lower edge gradually changes to a rock glacier, lateral moraines are traceable within 180 m, and the
Fig. 2. The maps of the glaciers of the Munku-Sardyk massif. а – schematic map by S. P. Peretolchin (1908); b – a portion of the contemporaneous tourist map “Munku-Sardyk – An Eternally White Golets” (2003). 1 – the Northern and Southern glaciers according to S. P. Peretolchin’s schematic map; 2 – glaciers on the contemporaneous tourist map; 3 – screes and taluses; 4 – lakes; 5 – altitude figures and summit names; 6 – principal summit of the Munku-Sardyk; 7 – passes and their numbers; 8 – contour lines run out every 40 m; 9 – streams; 10 – state border.
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bank of the terminal moraine reaches a height of 39 m. The movement of the glacier is suggested by transverse cracks in the open part of the ice up to 25 m long and up to 6 m deep, as well as the numerous transverse and diagonal subsidence cracks in the lower part. The southern glaciers in their lower part steeply precipitate into the gorge, and this does not create favorable conditions for formation of distinct terminal moraines. In the summer time, especially in foul weather, the Peretolchin glacier is hazardous because of its frequently occurring rockfalls (according to our observations, rockfalls recur at intervals of 15–20 min). The state of firn snow changes dramatically with climatic conditions of a year. Sometimes it is a sinter ice but more often a solid firn. In the summer of 2006, we discovered sinks in the terminal moraine which exposed the buried body of the glacier. In the warmer year of 2008, within the righthand lobe there emerged a further three such sinks, while the former sinks became significantly deeper. A study of these ice caves showed that the glacier actually did not decrease its length, but the lobe more than 100 m in length developed a stony jacket 1–1.5 m in thickness which gradually changed to a morainic bank. The fact that the site of emergence of the glacial flow from beneath the moraine changes every year also confirms the existence of a rock glacier. Recent years witnessed an abrupt warming and, accordingly, distinct changes of glacial-nival objects. Glaciers in their terminal part, without reducing in length, transform to rock glaciers, and the visible lower boundary of the glacier increased in height (by 17 m during 2006–2008 as evidence by GPS measurements). In the summit part, there was an increase of the gap between the Northern and Southern glaciers. Icings decay substantially toward the autumn, decreasing in height (compared with the old marks on tree stems) by about 2 m. The number and thickness of perennial snow patches decreased. There is taking place an encroachment of forest geosystems into mountain-tundra geosystems manifesting itself as the appearance of separate undersized larch trees (1–2 m) above the contemporary forest limit. On the other hand, some stems of dead trees that were detected on the morainic slope in the valley of the Bugovek river suggest that previously (perhaps in the Holocene) trees grew above the contemporary upper forest limit. The preserved stumps of larch trees are 1 m in diameter and presumably 250 years old. Results of radiocarbon analysis of wood samples would be instrumental in drawing the more accurate conclusions about the changes of climate in that historical period. It will be possible to refine the boundaries of the mountain geosystems and their genetic links through the use of the landscape map for the Munku-Sardyk massif whose compilation was started on the basis of remotely sensed data. Conclusion For the last 100 years the annual values of the positive trend of air temperatures have been 0.2–0.5 °С averaged
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over 10 years [13]. This leads to the northward displacement of the permafrost line, the rise of the upper forest limit in the mountains, the retreat of glaciers and their transformation to rock glaciers, and to a decrease in the area of golets (Alpine rocks). Structural transformation of geosystems is favored not only by a rise of air temperature but also by regional changes in humidification as well as by local anthropogenic impacts. Phenomena of this kind were recorded across the extended territories of Siberia, Northern Mongolia and Northwestern China [6, 7] and suggest the conclusion that these processes are fairly peculiar to local glaciological systems [14, 15]. Genetically, the rock glaciers occurring at the trough valley heads represent continuations of existing glaciers produced by accumulation of fragmented rock which is transported by this same glacier and fill up its lower part. At periods of warming, moraines and intermontane depressions develop thawed patches exposing the buried ice of the glacier. With a further development of the process of warming in the mountains in Eurasia deep inland, distinctive changes should be expected to occur in the established structure of geosystems: the mountain-forest, mountain-steppe, golets, mountain-tundra and nival-glacial geosystems. Investigations in key areas will offer a means of determining the trend of these changes and to create the quantitative information base for the dynamics of mountain geosystems. It would be of great interest to determine quantitative data on the movement of glacier snouts for given time intervals and on the development dynamics of the overflow ice, identify buried glaciers, and to compile the landscape map for the mountain massif with the use of state-of-the-art GIS technologies, navigation-topographic instruments and information obtained through remote sensing of the Earth. Using the latest remotely sensed data and GIS instrumentation we generated the maps for the surfaces of glaciers, and their steepness and relief pattern, which adds to and enhances, at the new information and time-efficiency level, our knowledge of mountain landscapes and glaciological processes not easily accessible on the globe. References 1. The History of the Semi-Centennial Activity of the Imperial Russian Geographical Society. 1845–1895. SPb, 1896, 468 p. 2. Peretolchin S. P. The glaciers of the Munku-Sardyk Range. Izv. Tomsk. tekhn. in-ta, 1908, v. 9, pp. 1–47. 3. Maksimov E. V. Concerning the glaciers of the Munku-Sardyk massif in the Eastern Sayan mountains. Izv. VGO, 1965, v. 97, issue 2, pp. 176–180. 4. Arefiev V. and Mukhametov R. On the Glaciers of the Altai and Sayan Mountains. Barnaul, 1996, 176 p. 5. Kitov A. D., Kovalenko S. N. and Drozdova O. V. Some details of the use of state-of-the-art methods of analyzing the MunkuSardyk landscapes. Proc. 13th Scient. Meeting of Geographers of Siberia and the Far East Commemorating the 50th Anniversary of the Institute of Geography SB RAS (Irkutsk, 27–29 No-
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vember 2007). Irkutsk: Institute of Geography SB RAS Publisher, 2007, v. 1, pp. 141–142. Plyusnin V. M., Drozdova O. V., Kitov A. D., and Kovalenko S. N. The dynamics of the mountain geosystems of southern Siberia. Geografiya i prirod. resursy, 2008, No. 2, pp. 5–13. Kitov A. D. and Plyusnin V. M. Features of local glaciological phenomena in mountain landscapes (exemplified by the Baikal-Urumchi transect). In: Sustainable Development of Territories: GIS Theory and Practical Experience: proc. Intern. Conf. InterCarto-InterGIS–14, Saratov–Urumchi, 24–26 June 2008. Saratov: International Cartographic Association, 2008, v. 1, pp. 130–137. Atlas of Lake Hovsgol. Moscow: GUGK, 1989, 118 p. Geological Map of the USSR. М–47–V. Ser. Eastern Sayan. Sc. 1:200 000. Author and compiler V. P. Arsentiev. Moscow: MINGEO SSSR, 1961, 1 sheet. Explanatory Note to the Geological Map of the USSR at a Scale
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of 1:200 000. М–47–V. Ser. Eastern Sayan. Moscow: Gosgeoltekhizdat, 1962, 56 p. The Evolution of the Earth’s Crust in the Pre-Cambrian and Palaeozoic (Sayan-Baikal Mountainous Region). Belichenko V. G., Shmotov A. P., Sezko A. I. et al. Novosibirsk: Nauka, 1988, 161 p. Lodochnikov V. N. The petrology of the Ilchiro-Mondinsky District. Trudy Vost.-Sib. geologoupravleniya, 1941, issue 28, 197 p. Gustokashina N. N. Long-Term Changes of the Main Elements of Climate on the Territory of the Baikal Region. Irkutsk: Institute of Geography SB RAS Publisher, 2003, 107 p. Plyusnin V. M. Landscape Analysis of Mountain Territories. Irkutsk, 2003, 257 p. Plyusnin V. M. Response of inland mountain systems to global climate change. Geografiya i prirod. resursy, 2007, No. 3, pp. 67–74.