NATURAL ENVIRONMENT AND HUMANS IN THE LATE PLEISTOCENE OF NORTHERN MONGOLIA*

The article presents the results of a comprehensive study of the kultur-bearing deposits of the Tolbor-4 site. Cytological analysis of the section allows us to conclude that the entire thickness of loose sediments of the monument belongs to the end of the Upper Pleistocene. The lower section belongs to the end of the Zyryan time, the middle part of the profile belongs to the Karginsky time, and the upper part, layers 2 and 3, belongs to the Sartan time. Horizons 4 and 5 may also correspond to the same period, but this assumption contradicts the chronological scale created based on the results of technical and typological analysis of archaeological material, analogues of which are found in dated monuments from neighboring territories. Finally, this contradiction can be resolved only after obtaining a series of absolute dates. The study of the palynological spectra of the Tolbor-4 monument deposits indicates a continuous and gradual aridization of the climate in this area. In general, the climate throughout the human habitation in the parking lot was favorable, without catastrophic changes.

Keywords: Upper Pleistocene, lithological analysis, palynological analysis of sediments, technical and typological characteristics of archaeological material.

Introduction

The history of the formation and development of Pleistocene landscapes as a habitat for primitive man is one of the most relevant topics of modern Paleolithic research. To study the mechanisms of cultural adaptation of ancient groups under the influence of natural factors in the Neo-Pleistocene epoch, reconstructions of the environment in specific areas of Paleolithic man's habitat are of primary importance. For the study of Paleolithic cultures of Mongolia, the study of the influence of environmental dynamics on changes in the behavior strategy of ancient people is particularly relevant. The specific natural conditions of this region caused the surface occurrence of the cultural layer of most of the Paleolithic objects located here. Therefore, any new stratified monument requires close and careful study. As a result of the work carried out by the joint Russian-Mongolian-American archaeological expedition, archaeological materials and the results of natural science studies of such stratified objects as the Tsagan-Agui cave and the Chihen grotto in the Gobi Altai were introduced into scientific circulation [Derevyanko et al., 2000, 2001]. In the 1990s, a paper was published that presented generalized data on the stratigraphy, geology, and paleogeography of the Paleolithic sites Orkhon-1 and -7 located in Southern Khangai (Derevyanko, Nikolaev, and Petrin, 1992). Unfortunately, the archaeological material of these sites was published very sparsely and practically not considered in the article.

* This work was supported by grant No. 07 - 01 - 00417a of the Russian Foundation for Natural Sciences, grant No. 7.3 of the Integration Projects of the Siberian Branch of the Russian Academy of Sciences for Basic Research in the Humanities "Formation and Evolution of Paleolithic Cultures of North, Central and South-West Asia", and the Russian Foundation for Basic Research project N 06 - 05 - 64671.

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Fig. 1. View of the Tolbor-4 parking lot from the south.

2. Reference sections at the Tolbor-4 parking lot. View from the north.

3. Correlation of reference sections of the Tolbor-4 site.

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in the context of the climatic and paleogeographic situation reconstructed from the data of natural science disciplines (Derevyanko and Petrin, 1990; Astashkin et al., 1993; Derevyanko, Nikolaev, and Petrin, 1994; Slavinsky and Tsybankov, 2006). In 2004, stationary excavations of the Tolbor-4 site located in the Selenga River basin in the Khangai Mountain country began (Figure 1). The history of the discovery of the monument, archaeological material, various aspects of splitting technology, and characteristics of the tool complex are sufficiently fully reflected in a series of publications (Derevyanko et al., 2006, 2007; Rybin et al., 2006).. The main purpose of this article is to determine the age of culture-bearing deposits of the Tolbor-4 monument based on data obtained by palynological and lithological methods of studying the section.

Materials and methods

There are practically no faunal remains found in the deposits of the Tolbor-4 site: they are absent in the upper horizons, and very few in the lower ones, and they are poorly preserved. It was also not possible to obtain absolute age data: all bone samples submitted for AMS 14C dating were found to be poor in collagen. In 2007, a series of samples were selected for TL dating. However, due to the insufficient amount of quartz, it was also not possible to conduct a survey using this absolute dating method.

The analytical procedure is based on the materials of two reference sections of the monument, which reveal the entire thickness of loose sediments-up to the rock base. The first incision (at the very edge of the terraced surface) was made in 2004, and the second (on a flat, almost flat section of the same surface) - in 2007 (Fig. 2). The shortest distance between the profiles is 8.5 m, the height difference is 158 cm. The 2004 wall illustrates the longitudinal structure of the slope, and the 2007 wall shows the transverse occurrence of layers. The stratigraphic patterns of both sections are well correlated with each other (Figure 3). We should note a significant increase in the thickness of the crop-bearing layers in the 2007 excavation and, as a result, the division of layer 3 (2004 section) into three lithological horizons. If in the 2004 excavation the total thickness of the sediments containing archaeological material was 80-85 cm, then in the 2007 excavation. it reached 160-165 cm from the daytime surface. As we moved away from the daytime surface, a different situation was observed: in the 2007 section, many of the layers recorded in 2004 disappeared, and the thickness became more monotonous. Horizons 5-9, identified in 2004, made up one layer - 7 (2007).Horizon 11 (2004) split into two layers-9, 10 (2007). Layer 16, defined in 2004 as a rock base, was not distinguished as an independent subdivision when describing the 2007 section. Samples from the 2004 section were selected for the palynological study, and the lithological characteristics were compiled from the sediments of the 2007 section (Fig.

Lithological characteristics of the section

The Tolbor-4 section is located on a foothill plume adjacent to a steep root slope along the left side of the Ikh-Tulbariin-Gol river valley. The thickness of the completed mine is 4.3 m. According to the fractional composition, a combination of statistical and dynamic indicators of the sedimentation process, the stratum is divided into 14 layers of different ages; 12 of them are characterized by granulometry (see Fig. 3).

Section from 2004

Layer 1-sod, light humusized loam of dark brown color with a thickness of 0.04 - 0.05 m. Artefacts are noted in the lower part of the turf and at the contact with the sediments of the underlying layer. Palynological zone Tbr 1.

Layer 2 is light gray, almost white, dense loess-like loam. It contains rare impurities in the form of fine clastic material. It lies at a depth of 0.05 - 0.12 m. Cultural horizons 1 and 2.

Layer 3 - light gray dense loess, saturated with small and medium-sized detrital material; the degree of saturation is average. It lies at a depth of 0.12 - 0.72 m. Cultural horizons 3 and 4. Palynological zone Tbr 2 (depth 0.50-0.55 m).

Fig. 4. Fragment of the 2007 reference section The northern wall. View from the south.

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Layer 4 is a grayish-yellow loess-like loam with rare inclusions of fine clastic material. It lies at a depth of 0.72 - 1.20 m. Cultural horizons 5 and 6.

Layer 5 - dense plastic loam of gray-brown color with an admixture of gravel. It lies at a depth of 1.20 - 1.42 m.

Layer 6 - grayish-yellow loess-like loam with brown and gray primazki, saturated with fine sand. It lies at a depth of 1.42 - 1.88 m.

Layer 7 is a gray-brown loam saturated with sand and medium-sized clastic material. It occurs at a depth of 1.88 - 2.08 m.

Layer 8 - gray-brown dense loam, saturated with gravel. It occurs at a depth of 2.08 - 2.16 m.

Layer 9 is a gray-brown dense loam with a low content of gravel. It occurs at a depth of 2.16 - 2.44 m. All three layers belong to the Tbr 3 palynological zone.

Layer 10 is a gray-brown dense loam, strongly saturated with sand and small rubble. It occurs at a depth of 2.44 - 2.50 m.

Layer 11 is a brown loose loess-like loam with interbeds of grayish-brown color. There are isolated fragments of medium size. It lies at a depth of 2.50-3.36 m. Palynological zone Tbr 4 (depth 3.25-3.30 m).

Layer 12 is a loess-like loam of gray-brown color, saturated with fine rubble and gravel. It occurs at a depth of 3.36 - 3.52 m.

Layer 13 is a medium-sized coarse-grained material. The filler is grayish-brown loam. It occurs at a depth of 3.52 - 3.84 m.

Layer 14 - brown dense loam with a large amount of dredge. It lies at a depth of 3.84 - 4.14 m.

Layer 15 - weathering crust. It occurs at a depth of 4.14 - 4.25 m.

Layer 16 - rock base.

Section from 2007

Layer 1 - soil and vegetation horizon with a thickness of up to 0.2 m.

Layer 2 is a whitish loess-like sandy siltstone (weighted average particle diameter x = 0.31 mm) (see table) of dense massive texture with inclusions of uncoated psephitic material with carbonatization along the stratification planes. It is broken by 1 - 10 cm wide subvertical cracks (plant roots); the lower boundary is uneven, generally subhorizontal.

The empirical distribution polygon (ESR) of sediments in this layer corresponds to the right-hand-open homodal two-fraction type (the content of the main fractions with a size of 0.315 - 0.14 and < 0.14 mm is slightly less than 90%) (Fig. 5). Fractions of other sizes - from fine crushed stone to medium - grained sand-in total reach 10%. The entire EPR is characterized by an increase in the number of grains with a decrease in their size. This circumstance is reflected in the asymmetry of the EPR with a mode shift to the left of the median, where small particles are concentrated (Trask skewness coefficients S k> 1 and statistical skewness coefficient α > 0), and, accordingly, better structured than coarse-grained ones in the right part. Horizon matter is not sorted (Trask sorting coefficient S0 = 2.09; standard deviation σ = 1.29). Accumulation was carried out in an environment characterized by

Results of granulometric analysis of samples

Sample number

Dimensions of fractions, mm

> 40

40 - 20

20 - 10

10 - 5

5 - 2,5

2,5 - 1,25

1,25 - 0,63

0,63 - 0,315

0,315 - 0,14

< 0,14

T-4-1

-

-

0,5

0,7

1

1,7

1,9

4,7

8,7

80,8

T-4-2

-

-

2,4

4,4

5

3,3

3,1

2,3

8,9

70,6

T-4-3

-

1,2

2,8

4

3,8

3,8

3,1

2,6

12,6

66,1

T-4-4

-

-

4,6

5,7

5

3,4

3,3

2,6

14,4

61

T-4-5

-

5,5

6

6,2

6,3

5,2

4,2

4

8,3

54,3

T-4-6

-

1,5

4,2

5,9

7

4,5

4,5

5,1

11,2

56,1

T-4-7

-

2,7

5,3

6,4

7,1

4,5

3,6

4

8,9

57,5

T-4-8

-

8,3

9,4

9,2

8,7

7,7

8,3

11

11

26,4

T-4-9

-

8

3,8

7

5,5

5,3

4,5

6,2

15,7

44

T-4-10

-

2,2

4,4

5

4,6

3,8

3,7

8,5

11,2

56,6

T-4-11

-

3,9

6,4

9,1

9,4

5,4

4,4

4,1

8,1

49,2

T-4-12

-

-

2,6

3,2

3,3

2,9

3

3,4

8,5

73,1

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5. Granulometric composition of layer 2 sediments.

6. Granulometric composition of sediments in layers 3 (T - 4 - 2), 4 (T - 4 - 3), and 5 (T - 4 - 4).

relative excess of the energy potential with a small displacement path and a deficit of the destroyed substrate in a stable state of the tectonic background (α > 0; excess τ > 0). High values of the coefficient of variation (v = 4.11) exclude the possibility of formation of deposits with specified parameters in the water basin and determine their slope genesis (the washout colluvium group) as a result of possible secondary redeposition of Aeolian dust by deluvial drift. It occurs at a depth of 0.2-0.5 m (sample T-4-1). Cultural horizons 1 and 2.

Layer 3 is a loess - like sandy siltstone (x = 1.05 mm), grayish-brown, dense, and non-textural, with a chaotic filling of uncut fragments of a gravelly-gravelly dimension and with a carbonate crust in the lower surface of the deposit. There are subvertical cracks extending from the upper horizon; a modern root is present in the left part of the described wall; the section is vague, generally subhorizontal. It occurs at a depth of 0.5-0.8 m (sample T-4-2). Capacity 0.3 m. Cultural horizon 3.

Layer 4 - with the physical and mechanical characteristics (x = 1.41 mm) noted for the previous horizon, and with a slight increase in the psephite content. It occurs at a depth of 0.8-1.1 m (sample T-4-3). The lower boundary is clear, subhorizontal. Cultural horizon 4.

Layer 5 is a sandy siltstone (x = 1.49 mm) of whitish, grayish-whitish color with a nostrate wall surface caused by shedding of debris during excavation, and with a vague lower section.

The uneven content of particles of different sizes from layers 3 to 5 forms a bimodal mixed-fractional right-side open EPR type (Fig. 6): particles with dimensions < 0.14 mm (they make up 2/3 or more of the total total weight of samples) and 0.315 - 0.14 mm (8.9 - 14.4%) dominate. Other gradations are characterized by low values-1-5 %. Another weakly expressed modal peak occurs in the dry sector of the particle size distribution spectrum. This indicates insignificant fluctuations in the energy levels of living forces (speed and volume) of sedimentation associated with a certain increase in the flow of external destructive processes that caused an increase in the amount of disintegrated substrate (α > 0).

The sorting of the material is very poor (S0 = 2.61-3.30; σ = 2.76 - 4.25); the distribution modality is shifted towards small particles (S k> 1); the kurtosis is positive within the first tens of units (τ = 7.81 - 24.65). Such statistical indicators indicate a more or less stable dynamics of the substance with a shortened path of its introduction throughout the entire period of sedimentation and a less calm tectonic regime compared to layer 2. The parameters of the coefficient of variability (v = 2.35 - 3.01) indicate the colluvial origin of the described layers. It occurs at a depth of 1.1-1.45 m (sample T-4-4). Cultural Horizon 5.

Layer 6 is a dense gravelly-sandy fine-grained siltstone (x = 3.46 mm) with an indistinct texture. It occurs at a depth of 1.45-1.8 m (sample T-4-5). In it, three layers with a thickness of 2 - 3 cm are distinguished, composed of a darker and grainier material at a depth of 1.45 - 1.48; 1.67 - 1.70 (the layer wedges out in the middle part of the described wall, bending when

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up) and 1.78-1.8 m. The upper and lower layers can be traced quite clearly along the strike with some variation in their thickness. Cultural horizon 6.

Layer 7 is a gray dense gravelly-sandy fine-grained siltstone (x = 2.00 mm) with signs of cementation by clay particles with latent subhorizontal stratification. It occurs at a depth of 1.8-2.25 m (sample T-4-6). This horizon contains brown spots of slightly inclined humusized material.

Layer 8 is a gray gravelly-sandy fine-grained siltstone (x = 2.55 mm) - an analog of the layers described above with clear, subhorizontal upper and lower boundaries. It occurs at a depth of 2.25-2.35 m (sample T-4-7).

EPR data of lithological horizons correlate with a two-modal (peaks - low - visibility and dominant - correspond to fractions 5-2.5 and < 0.14 mm) mixed-fractional bilateral-semi - open - open type (Fig. 7), which is characterized by a complete lack of sorting (S0 = 3.67-6.68; σ = 4.84-7.46); the variation of the distributions is shifted towards small particles (S k> 1); the kurtosis is positive (τ = 6.20-16.03). The main parameters indicate the movement of the substrate over a very short distance and the stability of the material balance, which was maintained during the entire sedimentation cycle under a conditionally variable tectonic background-first in the direction of some relaxation (layer 6), and then comparative strengthening (layer 7). The values of the coefficient of variation (v = 2.15 - 2.42) correspond to the slope genesis of these bundles.

Layer 9 is a gravelly-sand mixture (x = 5.23 mm) of dark brown color, dense aggregate state and massive texture. It lies at a depth of 2.35-2.6 (2.75) m (sample T-4-8). The thickness is not sustained along the strike, in the left part of the described wall there is an extension of up to 0.15 m, in general, the horizon is clearly separated in the presence of a subhorizontal lower section.

The total weight of crushed stone with a predominance of fine does not exceed 17.7 %; the mass fraction of sand particles, mainly large, is 17.9 %. The fine-grained part of the granulometric spectrum is represented by sands (38 %), in which fine - and medium-grained fractions (11% each) predominate, and silt-clay material (26.4%). This spectrum forms a bimodal two-way open mixed-fraction EPR type (Fig. 8).

Statistical parameters determine the absolute unsorted sediments (S0= 6.32; σ = 8.67), the right-hand slope of the EPR (S k> 1), and the positive kurtosis within the first units. This suggests that the accumulation occurred in an environment of noticeable energetism (α > 0) of the medium, with an extremely small transport path and an increase in the function of the tectonic and climatic components of the sedimentation process in this region. The values of the coefficient of variation (v = 1.66) suggest the obligatory participation in the formation of a layer of free-flowing water, which, with a large content of uncoated particles of the psephite dimension, indicates its mixed, slope-water origin (gravitational, deluvial, and fluvial groups)-colluvial-proluvial genotype.

Layer 10-is formed by brown gravelly-gravelly fine-grained siltstone (x = 3.94 mm) with a weakly pronounced layer-by-layer distribution of uncoated coarse fragments and sparse

7. Granulometric composition of sediments in layers 6 (T - 4 - 5), 7 (T-4-6), and 8 (T - 4 - 7).

8. Granulometric composition of sediments in layer 9.

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inclusions of small blocks. It lies at a depth of 2,6 (2,75) - 2, 9 (2,95) m (sample T-4-9). In the middle part of the described pack, there is a spot measuring 0.15 x 0.15 m of grayish-brown color with loose psephite material and an increased content of psammite particles (depth 2.7-2.85 m). The lower border is distinct, subhorizontal.

Layer 11 is a dense grayish-brown gravelly-sandy fine-grained siltstone (x = 2.08 mm). It occurs at a depth of 2.9 (2.95)-3.35 m (sample T-4-10). It differs from neighboring bundles by a large amount of fine sand-silt-pelitic matrix and a lower content of coarse-grained substrate.

Layer 12 is grayish-brownish gravelly-sandy fine-grained siltstone (x = 3.38 mm). It occurs at a depth of 3.35-3.65 m (sample T-4-11). It is characterized by an indistinct subhorizontal layered texture with a thickness of 2 - 5 cm. At the lower boundary there is a lens with dimensions of 0.2 x 0.07 m of loamy dense dark brown material with the inclusion of sand particles. The lower limit is determined by changes in the sediment structure.

9. Granulometric composition of sediments in layers 10 (T - 4 - 9), 11 (T-4-10), and 12 (T - 4 - 11).

10. Granulometric composition of sediments in layer 13.
9) and almost all the parameters of the sedimentation process calculated by mathematical statistics are adequate to the corresponding characteristics of layers 6-8.

Layer 13 is a sandy siltstone (x = 0.92 mm) with a subhorizontal section at the base. It occurs at a depth of 3.65-4.0 m (sample T-4-12). The strata are very poorly sorted (S0 = 2.37; σ = 2.72) due to the mixing of a large number of fractions with an approximately even content of crushed-sand-psammite dimensions and a sharply variable percentage of fine-clastic particles (Fig. 10). EPR is characterized by bimodality of distributions. Two modal peaks are characteristic - faintly noticeable and distinctly pronounced - corresponding to the fine sandstone range and the siltstone-clay sector. The mode is shifted towards small particles (S k> 1; α > 0); the kurtosis is positive. This indicates a relatively stable dynamic and tectonic background. The genesis of precipitation is inclined (v = 4.06).

Layer 14-lies at the base of the section at a depth of 4.0-4.3 m; the weathering crust is dark gray in color and crumbly in condition with separate, non-integrated fragments.

Geomorphological situation in the parking area

The research area belongs to the Orkhon-Selenga middle mountain region, which is part of the Khangai-Khentei mountain country and occupies its central, depressive part between the large arch-block uplifts of Khangai and Khentei (Geomorphologiya..., 1982). The main orographic elements of the region are positive (ridges with heights from 1,400 to 2,000 m) and negative (intermountain depressions and valleys of large rivers located at an altitude of 900 - 1,100 m) morphostructures. In general terms, the development of the relief is predetermined by zones of extended deep tectonic faults of long existence, which led mainly to the north-eastern orientation of the main ridges and depressions separating them.

Positive morphostructures. These are the two watershed northwestern lateral spurs of the Burengiin-Nuru ridge separating the valley of the Ikh-Tulbariin-Gol river in the study area

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from the valley of the Nariin-Tulbariin-Gol river from the west and the Altatyn-Gol and Hargannyn-Gol rivers from the east (all right tributaries of the Selenga River). The longitudinal axes of the ridges and valleys are laid northeastward along the tectonic feathering faults of the sublatitudinal segment of the Selengino-Orkhon deep fault.

The eastern side of the Ikh-Tulbariin Gol river valley is steep and steep. The watershed is rocky, sharp, with a chain of individual peaks - denudation rocks-remnants up to 10 - 15 m high (absolute height of 1,723 m), forming a jagged ridge with a width of 2 - 3 to 10 - 15 m. Processes of nival denudation and frost weathering with cracking and disintegration of rock outcrops are active in this part, which leads to the formation of small cryoplenes with low stepped upland terraces and large-block stone placers along the perimeter of the main outcrops. The saddles between the rocky peaks of a convex transverse profile, as a rule, have soft outlines and are covered with a gravelly substance. The apical parts of the slopes are often continuous outcrops of bedrock with large-block eluvium.

The main role in the formation of the upper part of the slopes is played by the processes of freezing (curdling), permafrost creep and slope rockfall water-stone flows during the period of snowmelt and heavy precipitation in the liquid phase. In addition, after the snow melts, there is a subsurface, permafrost deluvial washout, which is associated with the activity of water flowing not on the surface, but between large fragments.

The slopes in the lower part are massive, with varying degrees of dissection, depending on their orientation to the countries of the world; the steepness can reach significant values (30-35° or more). The sloping surfaces of the northern exposure are almost always devoid of vegetation; they are dry and steeper than the slopes of the southern exposure, which have a thin soil layer, are better moistened and laid out, and are covered with grasses, shrubs and larch forest.

The slope profile is convex in the upper part, straight in the middle part, and slightly concave in the lower part. The massiveness and relatively weak dissection of the slopes of the southern exposure can be explained by the fact that the vegetation cover contributes to the retention of large masses of surface water by the slopes. Low-power watercourses almost do not destroy slopes, while large ones cause erosion and can destroy the root system of a wooded slope. In view of these features, a relatively sparse network of erosion hollows has been developed here. Another reason for the formation of smooth large slopes is creep, which helps smooth out small irregularities and is the most effective form of mass movement of debris.

The modern surface of the southern slopes is formed by the processes of mass movement of layer-by-layer thawing material under conditions of a more even temperature regime and relatively uniform moistening (solifluction and defluction processes). The main slope - forming process on the northern slopes is deluvial plane washout with the participation of gravity drift. Facets - triangular slopes with ribbed projections of bedrock-are confined to steep surfaces and tectonic ledges in the valley side. In the case of washing and pruning of individual sections of the slope, scree is formed. Depending on the time of formation, some of the scree is buried under layers of young deluvium and blackened. In addition, regardless of the exposure, the slopes can be divided into two zones-upper (denudation) and lower-middle (accumulative). Accordingly, the thickness of loose sediments also changes - from tens of centimeters in the upper part to several meters at the foot.

The bottoms of erosion-denudation forms of various orders are well defined and are usually overlain by debris deposits of the slope paragenetic series of continental sedimentary formations - dispersion (scree) and deruption (landslide). Rectilinear gorge-shaped depressions are often forms of plowing with a shallow bottom up to 1 m in diameter, which were formed as a result of the movement of large-scale material under the influence of permafrost creep, solifluction and erosion processes. Closer to the foot of the slope, they acquire a V-shaped transverse profile and a new incision with a depth of 1-2 m, covered with crushed stone and gravel material.

The western side of the Ikh-Tulbariin-Gol river valley is less contrasting (maximum absolute height is 1,896 m, Mankhan-Ula). Along the base there is a wide sub-mountain plume; although it narrows in places, the board is characterized by a rather steep angle of inclination or even a near-vertical rocky exit. Some of its differences are deeper and longer erosion incisions that give the slopes a feathery appearance, pothole-ravine (in the upper part), expanding to the bottom with separate knee-like bends. These incisions often take on lateral, smaller erosional forms, at right or oblique angles with very steep walls and a narrow sill bottom due to the release of individual large blocks and undisturbed rock blocks. The plan has oblong, oval, dome-shaped, and irregular-conical vertexes. Narrow, rocky, steep - walled, and precipitous watershed ridges (up to 100-150 m long, 10 m high) with small teeth are common, corresponding to individual strata and veins

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indigenous rocks. They can form an amphitheater around catchment erosion funnels located in the apical zone of slopes, partially filled with landslide-scree dumps.

The bottom part of the macroslopes is separated from the actual bottoms of large valleys occupied by stationary watercourses (the Ikh-Tulbariin-Gol River and the Ikh-Bulag Stream) by foothill plumes, which are merged separate more or less large cones of outflow. They look like terraced surfaces that may have previously completely filled the incisions for their entire width. These landforms of various morphometric parameters have a complex genesis and are created by the joint activity of temporary watercourses and slope processes. Depending on the totality of manifestations of external agents, one or another form is formed at the foot of the slopes. These are the colluvial cones and plumes associated with the landslide-scree slopes of the northern exposure. The gravity-solifluction slopes of the southern exposure are directly associated with colluvial-solifluction rock flows, cones, and plumes. Deluvial-proluvial plumes of fluvial-gravity slopes and cones of time-flow outflow are developed independently of the orientation of the slopes.

Negative morphostructures. The territory under consideration is the most humid in the Orkhon-Selenga middle mountains: there is a fairly dense river network developed here, which belongs to the Selenga basin. The valleys of rivers and most tributaries correspond to zones of deep disturbances. The Ih-Tulbariin-Gola valley also has a tectonic foundation along the north-eastern direction fault. The valley floor with a width of 250-300 m and more in extensions in the form of semicircles is morphologically clearly expressed throughout its entire length. The floodplain stands out quite well; two levels are traced - low and high. The low floodplain is located along the riverbed, occupies the central part of the bottom, is covered with bright green grassy vegetation, sometimes with shrubs, partly swampy, developed hummock. A high floodplain with a height of up to 1 m can be traced along both slopes of the valley; a gently sloping surface is characteristic from the side to the channel on one side and downstream on the other. In some areas in the rear part of the floodplain is blocked by superimposed removal cones. In addition, there are remnants of old overgrown riverbeds in the valley floor, which give the floodplain surface a mosaic pattern. The riverbed of the pebble type meanders; its width is up to 2 - 2.5 m.

The bottom of the Ikh-Bulag stream (the left tributary of Ikh-Tulbariin-Gola) has a morphologically distinct incision; the valley is 100-150 m wide, and the stony channel is up to 1 m wide. The single-level floodplain is swampy in places, with fine-grained forms of nanorelief. The bottom itself in the lower course is developed in an older submontane plume. It expands funnel-like, eroding the latter, which is very noticeable in the mouth of the stream. Here there are traces of channel wandering movements that erode the bottom surface.

Palynological characteristics of the parking lot deposits

For analysis, samples of dry sediment weighing approx. 100 g were taken in sediments with an interval of 5 cm. Relatively representative spore-pollen spectra were obtained from materials from only 11 horizons-0 - 5, 50 - 55,120 - 125, 155 - 160, 175 - 180, 200 - 205, 210 - 215, 215 - 220, 230 - 235, 240 - 245 and 325-330 cm. Horizon spectra 120 - 125, 155 - 160, 175 - 180, 240 - 245 sm can be classified as poorly representative. All these horizons are represented by loamy lithological facies of gray or brownish color of varying intensity. Pollen and spores were extracted using a 10% solution of hydrochloric acid, a 5% solution of sodium pyrophosphate, a 10% solution of alkali (caustic potassium), concentrated hydrofluoric acid, and a potassium-cadmium heavy liquid with a specific gravity of 2.2. When preparing slides for microscopic examination, the treated material was placed in glycerol. Pollen and spores were determined using an Olympus microscope with a magnification of 400 times. The sum of counted pollen grains was 37-320 units. The relative abundance of each pollen taxon was determined from the sum of all counted pollen and spores (Fig.

The scale of changes in the steppe-forest index allows you to visually represent fluctuations in the ratio of steppe or forest vegetation in the study area and is calculated using the well-known formula

SLI = (Artemisia + Chenopodiaceae + Ephedra)/ (same +AR) x 100,

where AP is the sum of pollen from woody plants (Bezrukova et al., 2005).

The indices of humidity and temperature variability were calculated by combining the pollen taxa represented in the spectra into subgroups in accordance with the requirements of the plant taxa that produced them for the level of heat and moisture required for their growth. Pollen taxa are formed into subgroups: steppe, forest-steppe, light coniferous-taiga, dark coniferous-taiga, and subalpine (Demske et al., 2005). A separate subgroup consists of shrubs that are not included in the subal subgroup-

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11. Spore-pollen diagram of the 2004 section (western wall) of the Tolbor-4 site. The shaded areas of the diagram correspond to the position of the spectra represented by individual microfossils.

* Humidity index.

** Temperature index.

alpine taxa, and Boreal-alpine taxa. The humidity index is calculated using the formula

M = sqr (R), R = (S4 + S5 + S6 + S7)/(S1 + S2 + S3),

where sqr (R) is the square root; S4 is dark coniferous-taiga; S5 is subalpine; S6 is a subgroup of shrubs; S7 is boreal - alpine; S1 is steppe; S2 is forest - steppe; S3 is light coniferous - taiga taxa.

The temperature index is calculated by the formula M = sqr (R), R = (S2 + S3 + S4 + S6)/(S5 + S7). Both indices reflect only relative changes in the conditions of providing large plant formations with heat and moisture. Index values are expressed in conventional units.

Changes in the total composition of pollen and spores and variations in the relative abundance of individual pollen taxa made it possible to distinguish four palynostratigraphic units - pollen zones. They are designated by the abbreviation Tbr (Tolbor) with the corresponding numbers. Each zone reflects a stage in the area's vegetation change. The selection of Tbr zones 1, 2, and 4 is conditional, since it is based on individual pollen spectra.

The spore-pollen spectrum of the Tbr 4 zone (sampling depth 325 - 330 cm) is dominated by pollen from a group of herbaceous plants, among which the pollen of xerophytes - wormwood, haze, ephedra-dominates. There is pollen of mesoxerophytes - asteraceae, grasses, and sedges. The pollen group of woody plants includes pollen from scots pine, cedar pine, larch and spruce. A comparison of the composition of the spectrum of this zone and the review spectra of surface samples from different-genetic sediments in the Selenga basin showed that vegetation of dry, sagebrush-haze and ephedra steppes with the participation of rare-coniferous larch trees (the latter probably only in the valleys of watercourses) prevailed in the territory of the study area (Savina and Burenina, 1981; Savina et al., 1981; Tarasov et al., 1998]. Spruce could exist as a rare admixture to larch in the valleys. The nature of changes in the scale of humidity and temperature indices suggests climatic conditions with a lower level of heat than the current one and a low level of humidity close to the current one.

The Tbr 3 pollen zone combines eight pollen spectra in the 125-240 cm depth range. Six of the eight spectra are dominated by pollen from herbaceous plants. Moreover, if the spectra from the lower and upper parts of the zone are dominated by pollen of grasses from the Asteraceae family, cereals

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Pollen of the Artemisia genus dominates the spectra from the middle part of the zone. The exception is the spectra corresponding to a depth of 200 - 205 and 240 - 245 cm.

The first one is dominated by spores of the blood-red plunk Selaginella sanquinolenta (L.) Spring, and larch pollen. The second type is dominated by pollen from woody plants - scots pine, Siberian pine, larch, and to a lesser extent birch. The sequence of changes in the composition of plant associations and climate dynamics in the region during the formation of the Tbr 3 zone spectra is presented as follows. During the period of accumulation of deposits of the 240 - 245 cm layer, forest vegetation prevailed in the region, which was dominated by larch forests with cedar, pine and birch. Moreover, the low relative abundance of cedar and birch pollen suggests either the presence of these species in the form of an admixture in the composition of forests, or their existence at a rather distant distance from the parking lot. The local vegetation could be represented by larch forests, clarified, mainly cereals. The relative level of moisture available to plants was significantly higher than the current values, and the temperature regime was almost similar to the current one, but slightly lower. Later, during the formation of the layer at a depth of 230 - 235 cm, the local vegetation was already dominated by mesophytic steppe, mostly grass. In the most insolated areas - dry steppe with the participation of ephedra. The climate has become much colder and arid. Even later (depth 215 - 220 cm), mesophytic grass steppes were replaced by mesoxerophytic sagebrush steppes, which relatively quickly gave way to mainly xerophytic mixed grass-sagebrush-haze steppes. Larch was present at higher hypsometric levels, where the mode of providing moisture (soil)was reduced. it was higher due, most likely, to low summer temperatures and, accordingly, low summer evaporation. This is confirmed by the low values of available moisture and heat on the scales of humidity and temperature indices.

The low level of heat supply and the significantly increased level of moisture available to plants contributed to the spread of larch woodlands with a grassy cover of cereals and ferns at the next stage of development of the natural environment of this area. The rarefaction of larch trees during the formation of the layer at a depth of 200-205 cm is clearly indicated by the local expansion of the curtains of the blood-red plank. Its curtains are typical of stony mixed-grass steppes and are associated with communities of non-wooded rock habitats (Molozhnikov, 1986).

The appearance of sphagnum groups and shrubby birch simultaneously with tree birch was noted during the accumulation of sediments at a depth of 180-160 cm. Perhaps, in the river valley near the section, the process of waterlogging began in a cold climate and permafrost activation.

Some improvement in climatic conditions was typical for the time of layer formation at a depth of 120 - 125 cm. As a result, larch clusters reappeared near the section, and the area of pine trees expanded in the region.

The natural environment of the accumulation period of the Tbr 2 zone spectra can be characterized only conditionally due to the weak representativeness of the pollen spectrum. According to the composition of pollen and spores from this spectrum, larch woodlands and mesophytic steppe communities, mainly grasses, predominated near the section. In regional terms, the role of forest vegetation, in particular pine and birch, has increased, which indicates an increase in both moisture and heat supply.

During the formation of the subrecent spore-pollen spectrum (Tbr zone 1) (sampling depth 0 - 5 cm), the vegetation of the study area was represented by larch forests with a rare participation of pine and birch. Ilm Ulmus groups spread across the valleys. The increased level of heat, but relatively low level of available moisture prevented the appearance of Siberian pine in the area, although the rather high relative abundance of Siberian pine pollen in the spectrum of this zone indicates the expansion of dark coniferous forests in the mountain-forest belt of northern Mongolia, apparently in the late Holocene. It is possible that the high abundance of haze and lily pollen here may also indicate the impact of anthropogenic pressure on the local landscape.

The pollen record obtained reflects significant changes in the natural environment, in particular vegetation and climate of the studied territory, both at the local and regional levels. The composition of the spectra allows us to estimate the age of the studied sequence only in the most general sense - neo-Pleistocene. Pollen and spores of Pliocene plants are absent.

Conclusion

The detailed study of the Tolbor-4 formation represents the overall slope genesis of precipitation. The crowning section of the soil-vegetation layer has a Holocene age. The loess-like upper horizons-layers 2-5 (hereinafter referred to as the numbering of layers according to the 2007 section) - may have accumulated in the cold arid climate of the Sartan Mountain range.

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12. Change in the diameter of particles of channel-forming fractions (x) in the Tolbor-4 section.

13. Variation of the parameters of the coefficient of variation (v) of deposits in the Tolbor-4 section.

epochs. During this period, they were affected by loess-type weathering; material was transported via colluvial, deluvial, and possibly wind routes (Ryashchenko et al., 2006). The tectonoclimatic component of the accumulation process experienced an increase in the destructibility vector with periodic weakening, which was reflected in a gradual increase in erosion-denudation phenomena and an enlargement of the weighted average size of sediment particles (Fig. 12).

A relative maximum was reached during the formation of layer 6, which we believe is a reference layer, from which we can observe a certain cyclical variability of endo - and exogenesis processes during the formation of layers 6-8 and 10-12: a minimum, then an increase and again a slight decline (Fig. 13). These processes were most clearly manifested during the formation of layer 9: it is characterized by the largest particle size in the section and, as a consequence, participation in the accumulation of free-flowing water associated with the optimum of the Karginsky phase of the late Pleistocene, which generally corresponds to climatic warming and an increase in water content of this territory. Layer 13, which lies at the base of the stratum, can be correlated with the top of the section by the sum of indicators, except for afforestation. It was probably formed either at the end of the Yermakovsky or at the beginning of the Karginsky time, which is also confirmed by palynological data; the Tbr 4 zone is characterized as cold and dry. Layers 6-12 were formed in the Karginsky period. This period was characterized by sharp climate changes; this is evidenced by both the data of lithological studies and the results of palynological analysis. Ancient man first appeared at the Tolbor-4 site during the accumulation of layer 6 - in the second half of the Karginsky interstadial. The pollen spectrum obtained from materials from a depth of 120-125 cm is consistent with this period; it reflects a slight improvement in the natural environment in the vicinity of the site and the expansion of the forest area. The spore-pollen zone Tbr 2 corresponds to the period of formation of cultural horizon 4.According to palynology and lithology data, this was a kind of climatic optimum of the site. In the future, the climate gradually aridized (see Figure 11). Significant fluctuations in moisture and heat levels led to rather abrupt changes in vegetation and wildlife, as well as changes in the degree of availability of food and water resources for humans.

It should be noted that the conclusions obtained as a result of the analysis of archaeological material somewhat contradict the lithological scheme of the age of sediments. According to lithology data, geological layers 2-5 were formed in the Sartan period. The age of layers 4 and 5, in which cultural horizons 4 and 5 are located, respectively, is questionable. A comprehensive technical and typological analysis of the archaeological complexes of horizons 4 - 6 of Tolbor-4 makes it possible to assign them to a wide range of South Siberian and Central Asian sites of the early Upper Paleolithic period. The splitting technology at the site under consideration is very close to the main variants of parallel plate splitting previously defined for the complexes of the region. The tool set, which has local differences, also indicates the genetic connections of Mongolian families within the early Upper Paleolithic phenomenon of Southern Siberia. Materials from horizons 4-6 of Tolbor-4 show a combination of elements characteristic of the early Upper Paleolithic of Gorny Altai and Transbaikalia, and local specific features. The comparison revealed the attraction of Tolbor material to the group of local Mongolian authors. These are, first of all, Moiltyn am, Dorolzh-1, Chihen-2, whose age is approaching 30 thousand years and refers to-

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It is entirely related to the Karginsky time (Derevyanko et al., 2007). Of course, this contradiction can be resolved by having a series of absolute dates. Currently, a number of samples from layers 5 and 6 of the Tolbor-4 site are being tested at the Tucson Laboratory (Arizona, USA). And we hope to get radiocarbon AMS dates soon. There is no doubt that geological layers 2-3 (which contain archaeological horizons 1 - 3) belong to the Sartan period (Rybin, Gladyshev, and Tsybankov, 2007).

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The article was submitted to the Editorial Board on 13.05.08.

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