Principles of Classification and Mapping of Permafrost in Central Asia

Principles of classification and mapping of permafrost in Central Asia

G.F. Gravis & E.S. Melnikov Institute of Earth Cryosphere, Russian Academy of Sciences, Moscow, Russia Guo Dongxin, Li Shuxun, Li Shude, Tong Boliang, Zhao Lin & Nan Zuotong Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, China N. Sharkhuu Institute of Geography, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia A.P. Gorbunov, S.S. Marchenko & E.V. Seversky Permafrost Institute, Russian Academy of Sciences, Kazakhstan Alpine Geocryological Laboratory, Almaty, Kazakhstan

ABSTRACT: The agreement to prepare a uniform permafrost map of Central Asia by an international team (China, Mongolia, Russia and Kazakhstan) was reached at the International Symposium in Mongolia in September 2001. In this paper we consider some initial results of mapping mountain and plateau permafrost in Central Asia as the first step for geocryologists of the four countries. A brief review of the experiences in small-scale mapping of permafrost in Russia, China, Mongolia and Kazakhstan is provided. We distinguish two types of cryogenetic zones: high-latitudinal (polar) and low-latitudinal (alpine). The altitude of 500 m a.s.l. is suggested as a criterion for division of permafrost area into two types of cryogenesis. We propose two morphological types of alpine cryogenesis within the Central Asian permafrost area: mountain and plateau. General regularities of permafrost distribution, its structure and temperature, ice content and distribution of periglacial phenomena in the Central Asian permafrost area are briefly described.

1 INTRODUCTION of southern Russia, Mongolia, China, Kazakhstan and adjacent countries (Figure 1). At present, except for The distribution, mapping and modeling of permafrost the IPA permafrost map (Brown et al., 1997), there is in Argentina, Canada, China, Kazakhstan, Mongolia, no uniform map of Central Asian permafrost conditions. the Nordic and European countries, and Russia were one However, small scale permafrost maps have been of the major topics of the International Symposium on compiled for Central Asian territories of these regions. Mountain and Arid Land Permafrost which took place in Heginbottom et al. (1993) summarised corresponding Ulaanbaatar, Mongolia, September 2–4, 2001. Accord- major developments in permafrost mapping. The fol- ing to the first recommendation of the Symposium, an lowing is a brief review of these mapping approaches. international team of experts (China, Kazakhstan, Mongolia and Russia) is required to prepare a uniform 2.1 China map of Central Asian permafrost (Brown, 2001). Mapping of mountain permafrost of Central Asia is The map of snow, ice and frozen ground in China complicated by two circumstances. First, nonuniform (1:4,000,000), compiled by Lanzhou Institute of approaches, and as a whole, lack of studies of perma- Glaciology and Geocryology, Academia Sinica (1988) frost in this vast region. Secondly, lack of distinctions in shows regional distribution of the three types of frozen the principles of permafrost mapping. The poor infor- ground and the cryogenetic phenomena in these per- mation about frozen ground in the majority of moun- mafrost regions. These are (1) high latitute permafrost tains of Central Asia requires an understanding of the in Northeast China, (2) permafrost on Qinghai-Xizang general regularities of permafrost formation. It is impor- Plateau and (3) alpine permafrost in mountains of tant to analyse the experiences of permafrost mapping in the different countries and to employ a common usage of this experience. This collective experience and choice of the most acceptable methods of classifying and mapping are the basis for development of the uniform approach to the compilation a permafrost map of Central Asia.

2 SMALL-SCALE MAPPING OF MOUNTAIN PERMAFROST IN CENTRAL ASIA

The Central Asian region is the largest area of alpine permafrost in the world. This region includes the territories Figure 1. The Central Asian permafrost region. 297 West and East China. Permafrost conditions of the ter- map (scale 1:5,000,000) was completed in 1970. In ritory along the Qinghai-Xizang Highway have been 1982 one more variant of this map (scale 1:7,500,000) studied in detail and mapped (Tong et al., 1983) at the was published (“Geocryological map of USSR”, 1982). scale of 1:600,000. The distribution map (1:4,000,000) The compilation of the Geocryological map of of frozen ground in China was compiled by Xu & Guo the USSR (scale 1:2,500,000) was started at the Geocry- (1982). The relation of climate, vegetation, soils and nat- ology Department of the Moscow State University ural landscapes determine the latitudinal zonation from under the initiative of V.I. Kudryavtsev (Kudryavtsev south to north of Northeast China (Guo et al., 1981). et al., 1977). The map was completed in 1991 under A map of permafrost and periglacial phenomena the direction of E.D. Ershov and subsequently pub- distribution on Qinghai-Xizang Plateau and adjacent lished (Ershov, 1996). The map is the most complete mountain regions was compiled at 1:3,000,000 (Li & source of the geocryologic–cartographic information Cheng, 1996). The map reflects the boundaries of for the territory of Russia (see Williams and Warren regions such as predominantly continuous permafrost, 1999 for the English language translation). sporadic permafrost, seasonally frozen ground, short- The Map of Morphology and Permafrost Tem- term frozen ground, as well as the distribution of perature of Northeast and South of Siberia (scale periglacial phenomena. 1:2,500,000), compiled under the direction of I. A. A Map of Geocryological Regionalization and Nekrasov (1976) is an example of a special geocry- Classification in China at a scale of 1:10,000,000 has ological map. The relation between temperature and appeared as an appendix in the book “Geocryology thickness of permafrost was used within the mountain in China” (Zhou et al., 2000). Permafrost regions of territories. Another example is the special Geocry- China are divided into three major frozen ground ological Map of USSR (scale 1:4,000,000) compiled regions: Eastern, Northwestern and Southwestern. under the direction of A. I. Popov (1985). Two types of Within each region of frozen ground, sub-regions are distribution of cryolithogenesis are shown: syngenetic identified. In the Nortwestern and Southwestern regions and epigenetic, and the composition of ground and typ- sub-regions are selected as consistent with geomor- ical cryogenic textures are shown. phological units. The geocryological mapping on the landscape base Generally, the principle of mapping mountain and began to develop in 1960s in Western Siberia (Melnikov, plateau permafrost in China is based on permafrost 1981). Here geocryological maps were made only for zonality index or on degree of permafrost thermal sta- the plains. The first attempt to use the experience of bility depending on mean annual ground temperatures these operations for mapping of the entire permafrost (Cheng, 1983, Cheng & Dramis, 1992). A GIS-based area of Russia there was Geocryological Map of Russia map of permafrost distribution and thickness on and Mongolia (scale 1:10,000,000) compiled under Qinghai-Xizang Plateau using simulated data of soil the direction of E.S. Melnikov in 1993, which incor- temperature measurements from Chinese weather sta- porated into the circumarctic map (Brown et al., 1997). tions was presented recently (Nan et al., 2001). The compilation of such a map was possible due to appearance of landscape maps covering all territories of 2.2 Mongolia the former USSR (Isachenko, 1985; Gudilin, 1987). The most recent usage of landscape contours for Permafrost in Mongolia is concentrated in Altai, geocryological mapping is demonstrated on the Hovsgol, Khangai and Khentei mountainous regions. 1:7,500,000 map by Melnikov et al. (1996). The Distribution, thickness and temperature of permafrost mountains areas are depicted in differing colours for in Mongolia vary with altitudinal zonation of mountains. the altitudinal belts: arctic deserts and stony tundra; Based on altitudinal zonation of changes in permafrost mountain tundra; mountain sparse growth of trees; distribution geocryological maps of Mongolia have been mountain taiga; and mountain steppes. Within the alti- compiled (Gravis et al., 1990) at a scale of 1:2,500,000. tudinal belts the boundaries of complexes of cryo- The southern Siberian permafrost is characteristic of genic geological processes were delineated depending Mongolian territory. The southern permafrost boundary on relief and composition of ground. in Mongolia has not been studied and determined suffi- ciently. Permafrost conditions in the Selenge River Basin 2.4 Kazakhstan have been studied and mapped relatively well as com- pared to other territories of Mongolia (Sharkhuu, 1993). The problems in the study of geocryological conditions of the mountain countries were specifically 2.3 Russia analysed by members of the Kazakhstan Alpine Geocry- ological Laboratory of Permafrost Institute SB RAS In 1956, I.Y. Baranov created the first geocryological under the direction of A.P. Gorbunov. Geocryological map of the USSR (scale 1:10,000,000). The updated conditions of Pamir, Gissaro-Alai, Tien Shan and

298 Table 1. Characteristics of comparing principle and terminology for permafrost zonation used in each country of Central Asia.

Country (author), land Principle of permafrost Terminology of form and region zonation permafrost distribution Permafrost extent

CHINA 1.1. Middle height mountain Latitudinal zones Islands 30% region in the North-East Predominantly continuous 30–75% China (Xu & Guo, 1982). 1.2. Quinghai-Xizang Index or degree of Down belt 0° to 0.5°C High Plateau (Cheng, 1983). permafrost thermal Middle belt 0.5° to 3°C stability Up belt 3°C 1.3. Alpine mountains in West and Altitudinal belts Islands East China (Zhang et al., 1985). Predominantly continuous KAZAKHSTAN (Gorbunov et al., 1996) High Altitudinal subbelts Sporadic 40% Alpine Tien Shan and Pamir Discontinuous 40–80% mountains. Continuous 80% MONGOLIA (Gravis et al., 1990) Middle height Latitudinal zones Sporadic 1% (Altai, Hovsgol, Khangai and Scattered islands 1–5% Khentei) mountain and surrounding Islands 5–40% arid land regions Discontinuous 40–80% Continuous 80% SOUTHERN RUSSIA (Ershov, 1996) Mountainous regions Latitudinal zones Southern discontinuous 0.5 to 2°C with depressions and separate plateaus and plains Northern continuous 0.5 to 2°C

Dzungarskyi Alatau, located within the territories of 1978, 1988) and middle heights of the arid mountains Tajikistan, Kyrgyzstan, Uzbekistan and Kazakhstan of Mongolia (Gravis et al., 1990, Sharkhuu, 1993). were investigated (Gorbunov, 1978, 1988, Gorbunov According to the general patterns, extent and thick- et al., 1996) in areas between 36–46°N and 65–87°E. ness of permafrost increase in geographic latitudinal The regional altitudinal zonality of permafrost distri- zonality from south to north and in a rise of mountain bution for different mountain areas were elaborated altitudinal belts. The low limit of discontinuous per- (Gorbunov, 1978, 1988). The structures of altitudinal mafrost in Altai, Khangai and Khentei mountains, all geocryological zonality, regularity of permafrost and located at the same latitude, 2100, 1700 and 1300 m cryogenic features distribution and climatic factors were a.s.l., respectively. (Sharkhuu, 2000) the basis for regionalization of mountain permafrost. Regional patterns of permafrost distribution depend Based on altitudinal zonality of permafrost distri- on features and effects of winter air temperature inver- bution maps of permafrost distribution have been sion, vegetation and snow covers, ground composition compiled at 1:2,500,000; 1:1,000,000; 1:500,000 and and water content, slope orientation and steepness, larger scales. Mapping of mountain permafrost in surface and groundwaters, climatic and geothermal Kazakhstan uses an approach based on the division of conditions, and so on. Therefore, distribution and devel- mountain ranges into sub-belts of different types of opment of the permafrost varies from place to place permafrost distribution (Table 1). The altitudinal within a given permafrost region. boundaries of these sub-belts displace upwards from Coarse debris, forest and mossy covers provide a con- Dzhungar Alatau towards the southern part of Eastern siderable cooling effect and therefore favour permafrost Pamir about 140 m with a decrease of latitude by 1°. formation or preservation. However, where the snow cover is thick (over 50–100 cm), cooling or warming 3 GENERAL REGULARITIES OF effects on permafrost can be small. Small islands, PERMAFROST IN CENTRAL ASIA patches and lenses of permafrost in arid steppe lands of Mongolia, China and Kazakhstan can be developed 3.1 Distribution only in damp and silty sediments of depression and valleys. There are always taliks under large lakes, river General regularities of permafrost distribution are channels and along active hydrothermal and neotectonic determined by latitudinal and altitudinal zonality of fractures in regions with continuous permafrost. changes in climatic and topographic factors. Altitudinal Generally the difference in altitudes of permafrost zonality of permafrost distribution has been studied in distribution on south-facing and north-facing slopes is different regions of high mountains (Cheng, 1983, about 300–400 m (Qui et al., 1983). The difference in Qiu, 1993, Jin et al., 2000, Zhou et al., 2000, Gorbunov, elevations of the snowline on glaciers of northern and

299 southern slopes essentially increases in accordance with altitudinal level. This is the result of the influence of increase of aridity and continentality of climate. For topography, lithology, tectonics, hydrology, slope ori- Dzhungar Alatau this difference is usually about 100 m, entation, air temperature inversions etc. In the Inner in Tien Shan – 200–250 m, for Pamir 300–500 m. The Tien Shan (Ak-Shiyrak Range, 42°N), at the eleva- difference of altitudes of permafrost boundaries is much tions of 4100–4200 m, the lowest ground temperature more: in Dzhungar Alatau as it reaches 200–400 m, in is 5°C in the bedrock (Paleozoic schist) and 6.7°C Tien Shan – 300–600 and in Pamir – 500–800 m. in the ice-rich Late–Pleistocene moraines. The cor- It is necessary to note that the above comparison responding thickness of permafrost is 350–370 and is only relevant for slopes with an approximately iden- 250–270 m. In view of these findings it is rather cir- tical steepness, soil-vegetative cover and geologic cumspectly to use high-altitude gradients for estimat- structure. For Transili Alatau Range (Northern Tien ing the thermal characteristics of the ground at the Shan) there is a difference of about 350 m for the lower various hypsometric levels. boundary of discontinuous permafrost between sunny and shaded slopes. But for the lower limit of sporadic 3.3 Ice content permafrost this value is greater and reaches 500 m. The periglacial features in Mongolia have been studied 3.2 Temperature at different times (Gravis et al., 1990, Sharkhuu, 2001). Mountain permafrost in Mongolia is mainly epigenetic. Permafrost temperature and heat flux are the main In the upper (0.5–3.0 m) layers of the rock weathering parameters of thermal characteristics of permafrost. zone, the ice content is 3–10%. High ice content per- These parameters are very important to estimate not mafrost is characteristic of lacustrine and sometimes only distribution and thickness of permafrost, but also alluvial sediments with ice content 10–50%. Drained stability or sensitivity of permafrost to climate changes debris and gravely sands have massive visible cryogenic and human activities. They are obtained by means of textures, with ice contents that do not exceed 10–20%. temperature measurements in boreholes at permafrost However, ice content of epigenetic freezing water bear- key or monitoring sites. There are many such sites in ing gravely and sandy deposits have an iciness 20–40%. Russia, Mongolia, China and Kazakhstan (Burgess Rock glaciers, moraines, lacustrine deposits have et al., 2000). the highest ice content, and rocky massifs the least In order to obtain the above parameters, Sharkhuu ice. Ice content often reach 50% and even more. carried out geotemperature measurements in more Syngenetic frozen unconsolidated sediments with than 400 boreholes with depth of 10–200 m (Sharkhuu, ice wedges are common in most of the intermountain 2001) and located mainly in the Hovsgol, Burenkhaan, depressions with continuous and discontinuous per- Erdenet, Argalant, Nalaikh and Baganuur areas of mafrost in southern Russia. These sediments possess Mongolia. According to general regularities, the a very high ice content. However, predominantly epi- MAGT in the mountain altitudinal belt decreases about genetic frozen sediments in areas with sporadic and 0.4–0.6°C for each 100 m rise above the absolute sur- isolated permafrost are usually characterised by face height, and the latitudinal zonation increases by medium and low ice contents. 0.8–1.0°C for each 100 km from north to south. Under the influence of warming (20 cm thick snow cover, 4 UNIFIED CLASSIFICATION AND subsurface flow and infiltration of waters in well TERMINOLOGY drained ground) and cooling (forest and moss covers, high moisture content and silty ground and free air Differences in permafrost maps of China, Kazakhstan, convection in coarsely fragmental deposits) there is a Mongolia and southern Russia are the result of reduction of 0.5–2.5°C for each factor. The differences (1) various degrees of permafrost research between in ground temperatures between south-facing and territories, (2) various techniques of analysis of perma- north-facing slopes of mountains ranges from 0.5°C frost information, (3) lack of unified principles and to 3.0°C depending on the steepness of slope. There approaches in mapping mountain permafrost and exists winter air temperature inversion in intermoun- (4) a lack of unified common classification, terminol- tain valleys and depressions located at altitudes of ogy and legend for mapping mountain permafrost. In 1200–1800 m a.s.l. Values of geothermal gradient range order to elaborate principles of mapping mountain from 0.01°C/m on the watersheds and slopes of moun- permafrost, it is necessary first of all to compile the tains to 0.02 – 0 .03°C/m in valleys and depressions. permafrost classification of the Central Asian territory. Thermal observations in boreholes in Tien Shan We suggest to divide the permafrost are: high lati- and Pamir demonstrate a significant variability of tude and alpine. The circumpolar area of cryogenesis thermal regime (3–6°C) and thickness of permafrost is entirely defined by its high-latitudinal location and (100–120 m) within short distances even at the same intrinsically mainly one of geocryological altitudinal

300 zonation–zone of perennial frozen ground. The lead the adjective “alpine” in relation to elevation of low- processes of cryomorphogenesis are long-term freez- latitudinal area of cryogenesis. This allows a compari- ing and seasonal thawing-freezing. The area of alpine son of permafrost maps of circumpolar and alpine (low-latitudinal) cryogenesis is typical between 30°N permafrost areas. For developing the geocryological and 30°S. Here all processes of cryogenesis are pre- mapping of Central Asian mountains it is necessary to determined hypsometrically. In other words, the long- elaborate on an international landscape base for this ter- term, seasonal and short-term freezing–thawing is ritory. It will allow us to realize regionalization of terri- rather limited both in space and in time. These tory in view of the zonal factors, to allocate provinces circumstances determine the complex structure of within neotectonic area distinguished by character and a altitudinal geocryological zonality of the alpine cryo- degree of a relief ruggedness, and also geocryological genetic zone. It is possible to consider a lack of cryo- conditions. It is necessary to select landscapes formed genetic processes in the territories below 500 m a.s.l. on various geological–genetic complexes. as a diagnostic sign of the alpine area of cryogenesis Unified classification for a permafrost map of (Gorbunov, 1988). Hence, it is necessary in mountains Central Asia can be based on permafrost regionalization of Central Asia to refer to this area as alpine cryogen- of the territory. Each permafrost region and area is char- esis. It is necessary to select two morphological types acterised by a certain degree of similar permafrost con- within the area of alpine cryogenesis: mountain and ditions, or of similar patterns of permafrost distribution, plateau. To the first type are referred frozen and frosty thermal state, cryogenic structure and processes. A (dry permafrost) rocks of mountain ranges and valleys. small-scale uniform permafrost map of Central Asia Within this area the alpine type of relief predominates. shows permafrost distribution, temperature (according The second type includes permafrost of accumulative to borehole data), ice content within the upper layer of and denudation flatness (plateau). The classical exam- permafrost (up to a depth of zero annual amplitude) in ples of these two morphological types are Western Pamir accordance with the IPA map classification and also and Qinghai-Xizang (Tibetian) plateau, respectively. regional distribution of periglacial phenomena. As a basis of permafrost classification in Central Asia Regional vertical permafrost zonality for different we can assume the following: landscape and geomor- mountain territories is shown as an insert for the map. phological characteristics, humidity of mountains using the continental index (CI) of altitudinal permafrost zon- 5 CONCLUSION ality. CI was proposed by A.P. Gorbunov (1978) and is determined as a difference between altitudes of snow- This report presents a summary of existing permafrost line and lower boundary of sporadic permafrost. S. A. mapping and classification as well as permafrost con- Harris (1989) suggested to determine CI as a difference ditions in Central Asia. The essential differences in between altitudes of snowline and lower boundary of permafrost definition and mapping are discovered. It continuous permafrost. It is necessary to agree with this is notice that not uniform of knowledge of permafrost improvement, as the boundary of continuous permafrost conditions within the Central Asian region. The first is easier to determine and is more stable. step in compilation of a new regional permafrost map Some definitions such as “island”, “discontinuous” at a scale of 1:2,500,000 must be elaboration of uni- and “continuous” permafrost in connection with the form legend adjusted with the authors. The next step is character of alpine permafrost distribution are not compilation of different parts of the map for Chinese, absolutely correct. There are a number of difficulties Mongolian, Russian and Kazakhstan territories. In this when this approach is used for the mountain permafrost operation the landscape maps should widely be used. It area. On the map continuous permafrost near the upper should be noted that geocryological characteristics part of ranges and peaks looks like separate islands, such as permafrost temperatures, depths of seasonal which has no resemblance with continuity. Cheng freezing–thawing, distribution of cryogenic geological Guodong (1983) was one of the first to pay attention to processes are to the largest degree linked with land- this circumstance and proposed an alternative terminol- scape boundaries. Using these links it is possible to ogy for different types of permafrost distribution in line extrapolate of permafrost characteristics from of the with its temperature (see Table 1). It is suggested to well investigated territories into poorly investigated select three geocryologycal belts subdivided into nine regions. The last step in the compilation of Central subbelts, where the permafrost belt is subdivided into Asian Permafrost Map consists of joining the separate subbelts: stable, substable and instable permafrost sub- regional parts into a uniform map. belts. On the other hand we should use a terminology and classification for mountain permafrost compatible ACKNOWLEDGEMENTS with circumpolar permafrost areas. As a first step in this direction it is proposed to use the terms “island”, “dis- Partial financial support for participation in the continuous” and “continuous” permafrost, but with Mongolian Symposium and consultations in China

301 were provided by grants at the International Arctic Kudryavtsev, V.F., Kondratieva, K.A., Gavrilov, A.V., Research Center, Fairbanks, Alaska, the National Snow Zamolotchikova, S.A. & Trush, N.I. 1977. Geocryological and Ice Date Center, Boulder, Colorado and Cold and map of USSR scale of 1:2,500,000 and its role for engineer–geologic estimation of permafrost territory. Method Arid Regions Environmental and Engineering Research engineer–geologic investigations and mapping in the Institute Chinese Academy of Sciences, Lanzhou, permafrost area. Yakutsk. Yakutsk books pub.: 9–11. respectively. The authors thank Dr. Jerry Brown for Li, Sh. & Cheng, G. 1996. Map of Frozen Ground on Qinghai- his encouragement and advice for the initiation of this Xizang Plateau. Lanzhou, China: Gansu Culture Press. Map of snow, ice and frozen ground in China. 1988. Compiled project. We also thank Dr. Stephan Gruber and anony- by Lanzhou Institute of Glaciology and Geocryology, mous reviewer for their valuable comments. Academia Sinica. In Shi Yafeng & Mi Desheng (ed.), China cartographic publishing house. Beijing. Melnikov, E.S., Gravis, G.F., Konchenko, L.A. & Molchanova, REFERENCES L.S. 1996. Map of cryogenic physiogeological processes of Russia at a scale 1:7,500,000. Fundamental investiga- Geocryological map of USSR. 1982. Scale 1:7,500,000. In tions of a cryosphere of the Earth in Arctic and Antarctic Baranov, I. Y. (Ed.), Moscow, GUGK. Regions (results and perspectives). Puchshino. 131–134. Brown, J. 2001. International Symposium on Mountain and Melnikov, E.S. 1981. To development of methodological bases Arid Land Permafrost and Field Exursions in Mongolia. of regional engineering geology. Engineering geology, 6: Frozen Ground, 25: 7–11. 3–16. Brown, J., Ferrians, O.J., Jr., Heginbottom, J.A. & Melnikov, Method of permafrost survey. 1979. Moscow. Moscow State E.S. (compiled and edited). 1997. Circum-Arctic Map of University Pub. permafrost and ground-ice conditions. Scale Nan, Z., Li, S. & Liu, Y. 2001. Permafrost distribution map- 1:10,000,000. United States Geological Survey. ping on Qinghai Xizang plateau based on mean annual Burgess, M., Smith, S.L., Brown, J., Romanovsky, V. & Hinkel, K. ground temperature and its further applications. Extended 2000. Global Terrestrial Net-Work for Permafrost (GTNet- abstracts of International Symposium on Mountain and P): Permafrost Monitoring Contri-buting to Global arid land Permafrost, 2–7 September 2001. Ulaanbaatar: Climate Observations. Ottawa, Canada: Geological Mongolia. 48–54. Survey of Canada, Current Research, 2000-E14. Nekrasov, I.A. 1976. Permafrost area of North-East and South Cheng, G. & Dramis, F. 1992. Distribution of mountain per- of Siberia and regularities of its development. Yakutsk. mafrost and climate. Permafrost and Periglacial Processes, Yakutsk books Pub. 3(2): 83–91. Popov, A.I. 1985. Cryolithological map of USSR (for per- Cheng, G. 1983. Vertical and horizontal zonation of high-alti- mafrost area). Scale of 1:4,000,000. Moscow. GUGK. tude permafrost. Fourth International Conference on Qiu, G., Huang, Y. & Li, Z. 1983. Basic characteristic of perma- Permafrost. Washington. 136–131. frost in Tianshan, China. Proc. of the 2nd National Confer- Ershov, E.D. (Ed.) 1996. Geocryological map of USSR. Scale ence on Permafrost. Gansu People’s Publishing House. of 1:2,500,000. Qiu, G. 1993. Studies on mountain permafrost in Asia. Proc. Gorbunov, A.P. 1978. Permafrost investigations in high-mountain. of the Sixth International Conference on Permafrost. 5–9 Arctic and Alpine Research, 10(2): 283–294. July 1993, Beijing, China. 2: 1028–1030. Gorbunov, A.P. 1988. The alpine permafrost of the USSR. Sharkhuu, N. 1993. Permafrost in the Selenge River Basin. Proc. of Fifth International Conference on Permafrost. Proc. of the Sixth International Conference on Perma- Tapir Publishers, Trondheim, Norway. 1: 154–157. frost, 5–9 July 1993, Beijing, China. 2: 1223–1226. Gorbunov, A.P., Seversky, E.V. & Titkov, S.N. 1996. Geo- Sharkhuu, N. 2000. Regularities in distribution of permafrost in cryological conditions of Tien Shan and Pamir. Yakutsk. Mongolia. Transitions of the Institute of Geoecology, Gravis, G.F., Sharkhuu, N. & Zabolotnik, S.I. 1990. Mongolian Academy of Sciences. Ulaanbaatar, 217–232. Geocryology and geocryological zonation. National Atlas (In Mongolian). of Mongolia. GUGK of Mongolian Republic and USSR, Sharkhuu, N. 2001. Permafrost mapping in Mongolia Ulaanbaatar/Moscow Plates: 40–41, (scale 1:4,500,000). Extended abstracts of International Symposium on Gudilin, I.S. (Ed.). 1987. Landscapes map of USSR at a scale Mountain and arid land Permafrost, 2–7 September of 1:2,500,000. VSEGEI. 2001. Ulaanbaatar: Mongolia. 63–67. Guo, D., Wang, S., et al. 1981. Division of permafrost regions in Tong, B., et al. 1983. A map of permafrost along the Qinghai – Daxiao Hinggan Ling, Northeast China. Glaciology and Xizang Highway (1:600,000). Professional Papers on Cryopedology, 3(3). (In Chinese) Permafrost Studies of Qinghai-Xizang Plateau, Science Harris, S.A. 1989. Continentality index: its uses and limita- Press. tions when applied to permafrost in the Canadian Williams, P.J. & Warren, M.T. 1999. Geogryological map of Cordillera. Physical Geography, 10: 268–282. Russia and neighbouring republics, 1:2,500,000. English Heginbottom, J.A., Brown, J., Melnikov, E.S. & Ferrians, O.J., language edition, Geotechnical Sciences Laboratory, Jr. 1993. Circumarctic map of permafrost and ground ice Carleton University. conditions, in Proc. of Sixth International Conference on Xu, X. & Guo, D. 1982. Compilation of the distribution map Permafrost. South China University of Technology Press, (1:4,000,000) of frozen ground in China. Glaciology and Wushan, Guangzhou, China. 2:1132–1136. Cryopedology. 4(1). (In Chinese) Isachenko, A.G. 1985. Landscapes of USSR. Leningrad. Zhou, Y., Guo, D., Qiu, G., Cheng, G. & Li, S. 2000. Leningrad State University Pub. Geocryology in China. Science Press. (In Chinese) Jin, H., Cheng, G. & Zhu, Y. 2000. Chinese geocryology at the Zhang, T., et al. 1985. Influence of snow cover on the lower turn of the twentieth century. Permafrost and Periglacial limit of permafrost in Altay mountain. Journal of Processes, 11: 23–33. Glaciology and Geocryology, 7(1). (In Chinese)

302