a mountain system in Southern Siberia, in the southern part of Krasnoiarsk Krai and the northern part of the Tuva ASSR. The Zapadnyi Saian begins in the upper reaches of the Malyi Abakan River (east of Lake Teletskoe) and extends northeast for about 600 km until its junction with the Vostochnyi Saian at the sources of the Kazyr and Uda rivers.
Geological structure and mineral resources. The folded structure of the Zapadnyi Saian has a northeast strike and forms the inner part of the Altai-Saian folded region. It was formed in the age of Caledonian folding (during the Silurian period). On the north, east, and south it is surrounded by Salair (Cambrian) structures, which also form a narrow belt of the northern slope of the Zapadnyi Saian. Here deposits from the Lower and Middle Cambrian are widespread, including spilite, porphyrites, flinty slates, tuffs, tuffites, graywacke sand-stones, and reef limestones with granitoid intrusions. Lower Cambrian formations are discordantly covered by a rock mass of conglomerate and sandstone from the Upper Cambrian period. There are small amounts of red volcanic rock from the Devonian period.
The basic (Caledonian) structure of the Zapadnyi Saian is formed by two marginal anticlinoria with a synclinorium between them. The anticlinoria are composed of Lower and partially Middle Cambrian metamorphosed argillaceous flinty slates, greenstone effusive rocks, quartzites, and limestones. The rocks contain intrusions of small bodies of ultrabasic rocks. In the northern (Dzhebashskii) anticlinorium the tec-tonic block among Cambrian deposits is composed of Pre-cambrian metamorphic schists. Discordantly lying Upper Cambrian detrital rock, Silurian terrigenous carbonaceous rock, and Devonian red volcanic rock, filling superimposed depressions, are less widespread in the anticlinoria. The synclinorium is composed of a thick (up to 15 km) continuous sandstone-shale series of the Upper (and partly the Middle) Cambrian, the Ordivician, and possibly the Lower Silurian. The series consists of fine-grained terrigenous rock, which gives way to terrigenous-carbonaceous deposits of the Silurian. Devonian red rock, as well as carboniferous terrigenous rock, fills superimposed depressions. An intrusion of large masses of granitoids is assigned to the Devonian. Faults play a large role in the structure of the Zapadnyi Saian.
Minerals are found in the border areas of the Zapadnyi Saian. Deposits of iron and copper-cobalt ores are associated with the Cambrian intrusion of the northern slope. Gold, nickel, and chrome ores and deposits of asbestos are linked with border anticlinoria, particularly with ophiolite belts. Ores of silver, molybdenum, lead, and zinc are found in Devonian granitoids.
G. A. KUDRIAVTSEV
Topography. The Zapadnyi Saian is a system of comparatively narrow ranges, both flat and peaked, divided by the dense fluvial network of the Enisei basin. In the central part of the Zapadnyi Saian, the mountain system ends abruptly in the north at the vast Minusinsk Basin, and at the foot of its southern slope lies the broad Tuva Basin. On the southern slope of the Zapadnyi Saian, between the Mirskii and Kurtushibinskii ranges, is the Us Basin, and at the foot of the southern slope of the Kurtushibinskii Range lies the TuranUiuk Basin.
The contemporary mountain topography of the Zapadnyi Saian was formed at the end of the Neocene and beginning of the Anthropogenic period by domelike uplifts that were accompanied by differentiated movements of individual blocks, intensive erosive dissection, and repeated glaciation of the most uplifted ranges. The glaciation was primarily of the mountain-valley type. Few large segments of the old leveled relief have been preserved owing to the denser and deeper dissection of the mountain system by the valleys of the Enisei tributaries.
The western part of the main (watershed) range of the Zapadnyi Saian, as far as the deeply cut Enisei Valley, is characterized by a typical alpine relief with elevations of 2,800 to 3,000 m. To the south of the main range is the highest point in the Zapadnyi Saian, Kyzyl-Taiga Mountain (3,121 m), and at the base of the ridge of the main range lies the highly uplifted (1,500–2,000 m) Alash Plateau, which ends abruptly at the Khemchik River valley. The Bai-Taiga massif (3,129 m), rising along the right bank of the Alash River, has also been included by some investigators in the Zapadnyi Saian system.
East of the Enisei Valley the elevations of the main range decrease to about 2,000 m (a maximum of 2,263 m), and the terrain acquires a predominantly medium-altitude character (with the exception of the central part of the Oiskii Range, the adjoining Aradan Range, and the Ergaki Range, which have an alpine relief). West of the main range two branches emerge: the northeast (Kantegir, Sabinskii, Dzhebashskii, and Borus ranges) and the southeast (Khemchikskii and Kurtushibinskii ranges). At the western end of the Oiskii Range (the northeast branch) and the eastern end of the Ergaki Range (the southeast branch) these branches again approach the main divide. From the sources of the Us and Amyl rivers the elevations of the main divide (here called Ergak-TargakGaiga or Tazarama) gradually increase, reaching nearly 3,000 m at the junction with the Vostochnyi Saian system. Most of the lateral ranges, with elevations of 2,000–2,500 m, have a medium-altitude terrain.
Climate. The climate is continental, with long, cold winters and short summers (cool in the mountains). On the northern and southern slopes of the Zapadnyi Saian, at elevations of 1,000–1,400 m, the average January temperature ranges from -20° to -25°C, and in the intermontane basins it may drop to -30°C. In the mountains, particularly in high mountain regions, summers are marked by changeable weather and low temperatures (the average July temperature is 10°-12°C). In the intermontane basins summers are warm, with average July temperatures of up to 20°C. Precipitation occurs mainly in the summer, and depending on the elevation of the locality and on the direction of the slopes, it varies greatly: from 400–500 mm per year in the northern foothills to 1,000–1,200 mm on the northern slopes, which are exposed to moist air flows. On the southern slopes, which receive no rain, and in the intermontane basins precipitation amounts to 400–500 mm and 300–350 mm, respectively. There are no contemporary glaciers in the Zapadnyi Saian, but many firns are pre-served throughout the summer and in places firn masses occupy large areas.
Rivers and lakes. The river system is part of the basin of the Enisei, which intersects the Zapadnyi Saian in a narrow, deeply cut gorge with a large number of rapids and races, preventing navigation. All the rivers have a typical mountain character. River valleys, however, or the parts of river valleys that coincide with bedrock strikes have gentler forms than river valleys cutting transversely across mountain ridges. The latter generally have very steep and rocky slopes. The most important and deepest rivers of the northern slopes are the Abakan and Kantegir and the upper reaches of the Amyl. The rivers of the southern slopes, including the upper reaches of the Alash and Ak-Sug (left tributaries of the Khemchik) and the Us, Uiuk, and Systyg-Khem (right tributaries of the Bii-Khem), are usually shorter and not as deep. Rivers are fed mainly by melting snow (second half of May to early June) and by rain (July and August, the period of the greatest rainfall). They open up in late April and early May and freeze in late October and early November. The large reserves of hydroelectric power in the basin of the upper course of the Enisei and favorable geological and geo-morphological conditions have made it possible to begin construction, in the Enisei Valley, of the very powerful Saian Hydroelectric Power Plant. After the plant has been built and a large reservoir created, all the rapids of the Enisei will be flooded, permitting normal navigation as far as Kyzyl in the Tuva ASSR.
Most of the lakes of the Zapadnyi Saian are found in cirques in the ridge area of the divide. The largest lakes are on the southern slopes of the mountain systems, including Kara-Khol’ at the source of the Alash River, Sut-Khol’ on the southern edge of the Alash Plateau, and Emgen-Khol’ and Khalet-Khol’ on the southern slopes of the Ergak-TargakTaiga Range.
Landscape types. The basic landscape types are mountaintaiga, occupying almost all the northern slopes and the upper parts of the southern slopes of the Zapadnyi Saian; mountain forest-steppe, especially characteristic of the southern slopes of the ranges; and alpine, found in the summit areas of ranges above timberline.
The pine and birch forest-steppe of the Minusinsk Basin rims the Zapadnyi Saian on the north. In piedmont areas these landscapes give way to a belt of light coniferous (larch) and broad-leaved (birch and aspen) forests on mountain gray forest soil and sometimes on soddy podzolic soil. A dark coniferous taiga of cedar, fir, and spruce (the latter found mainly in river valleys) with a continuous mossy cover on mountain taiga soils predominates on the northern slopes at elevations of 800–900 to 1,500–1,800 m; these ranges gener-ally have a typical medium-altitude relief. Along their upper border the taiga forests gradually thin out and give way to sparse cedar and larch forests.
A large part of the slopes facing the Tuva Basin has mountain forest-steppe landscapes. The slopes with southern exposure are covered with mountain steppe on chestnut soils, and light larch park-type forests on mildly podzolized gray forest soils occupy the slopes with northern exposure. Continuous light coniferous larch forests appear only in the central part of the southern macroslope of the Zapadnyi Saian. At greater heights the larch forests give way to a belt of cedar-larch and cedar forests on mountain taiga soils, rising to elevations of 2,000–2,200 m. Thus, predominantly “Central Asian” rather than “Siberian” high-altitude landscapes characterize the southern slopes of the Zapadnyi Saian.
These differences also have an effect on the types of animals inhabiting the northern and southern slopes. Common to the northern slopes are squirrel, blue hare (Lepus timidus), fox, Siberian weasel (Mustela sibirica), elk, roe, maral (Cervus elaphus maral), hazel hen(Tetrastes bonasia), capercaillie, woodpeckers, and nutcrackers. In addition to the above, many steppe animals not found in the dark coniferous taiga, such as the long-tailed Siberian suslik, Richard’s pipit, and the hen harrier, may be found on the southern slopes. The number of steppe varieties increases considerably in intermontane basins.
The alpine landscapes, characterized by severe climatic conditions and by long and cold winters and short and cool summers, are less varied. Along with the different varieties of mountain tundra predominating in level areas, there are shrub thickets and alpine and subalpine meadows on mountain meadow soils, alternating with rock streams often almost to-tally devoid of vegetation, distributed throughout the Zapadnyi Saian. The animals of this region are either alpine, such as the Altai pika, willow grouse, and alpine ptarmigan, or varieties found in the mountain-taiga zone, including Siberian chipmunk, ermine, Siberian weasel, weasel, sable, brown bear, and elk.
The Zapadnyi Saian is crossed by the Abakan-Kyzyl (the Us route) and Abaza-Ak-Dovurak highways. Many of its regions are popular hiking and boating areas and have potential for development as vacation areas.
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I. G. NORDEGA