Ciscaucasia

Ciscaucasia - NASA satellite imagery

Geological structure

A significant territory of the Ciscaucasia in the north and in the middle part has a platform structure with a Hercynian folded base. This territory belongs to the Scythian platform . The age of the folded foundation of the Western and Middle Ciscaucasia is Early Hercynian, and the age of the geosynclinal foundation of the northern part of the Eastern Ciscaucasia is Late Hercynian ^[1] .

In the lower reaches of the Kuban and Terek , respectively, the Indolo-Kuban and Tersko-Kum depressions are located, which belong to the marginal trough of the Alpine geosynclinal region — the Alpine foothill trough, complicated in the middle by a platform structure with a Hercynian folded foundation ^[2] .

The surface of the Ciscaucasia is composed of anthropogenic , Neogene, and Paleogene sedimentary deposits. On the Stavropol Upland, the Paleogene and Neogene strata form platform-type folded structures. The folds of the Tersky and Sunzhensky ranges consist of Neogene rocks and complicate the southern wing of the marginal deflection. In the area of Cavminvod, there are volcanic masses of the laccolith type ^[2] .

Physical-geographical zoning

Orographically, the Ciscaucasia is divided into:

• Western Ciscaucasia
  • Kuban-Priazovskaya lowland (north of the Kuban )
  • Prikuban inclined plain (south of the lower Kuban )
  • Kuban delta and adjacent Taman Peninsula ( Priazovskaya delta lowland )
• Middle Ciscaucasia
  • Stavropol Upland (up to 831 m)
  • Tersko-Sunzhenskaya Upland (Tersko-Sunzhensky interfluve) with the anticlinal Sunzhensky (up to 926 m) and Tersky (593 (690?) M) ridges (and the synclinal Alkhanchurt valley separated between them (ridges))
  • between them (between hills), in the south - domed mountains rising in the plain - laccoliths of the Mineralovodskaya group:
    • Mashuk - 992 m
    • Beshtau - 1402 m
    • Iron - 852 m
    • Forking - 926 m
    • Snake - 994 m , etc.)
• Eastern Ciscaucasia
  • Tersko-Kuma lowland
  • Nogai steppe
  • Caspian Lowland (Black Lands)

Climate

The Caucasus is located in the border zone of the spheres of influence of the moist air masses of the Atlantic and the Mediterranean Sea on the one hand, and the dry continental spaces of the interior of Eurasia on the other hand. The Ciscaucasia belongs to the Atlantic-continental steppe climatic region, with the bulk of the Ciscaucasia entering its western subregion, and the Tersko-Kuma lowland - into the eastern. The Tersko-Kuma lowland differs from other parts of the Ciscaucasia by its particularly sharp continentality and aridity, which determine the semi-desert character of its landscapes ^[3] .

The climate of the Western and Middle Ciscaucasia is characterized as steppe: moderately continental semi-dry, with unstable moisture. The annual temperature amplitude is 25–28 degrees. Summer is very warm (average July temperature is 21-24 degrees), winter is moderately cold (average January temperature is -2-5 degrees. There are frosts up to -30-30 degrees. The snow cover of most of the territory is thin and often unstable. The average rainfall is 450— 600 mm per year, less than the norm of precipitation falls on the Taman Peninsula (300-400 mm) and the northern and eastern slopes of the Stavropol Upland (370-420 mm) .More than the average norm for this territory, precipitation occurs in the most elevated and located on the way western cyclones south -western of the Stavropol Upland - 600-800 mm per year. The central part of Mineralovodsk district is also characterized by increased moisture, due to the influence of heaped laccoliths (more than 600 mm per year). Also, more precipitation than on the neighboring plains in the western part of Sunzhensky ridge and on the Prikubanskaya plain (except for its northern part).

Adverse conditions include droughts , frequent in the northeastern Stavropol Territory , in the east of the Tersko-Sunzhenskaya Upland , in the Chechen Plain . In the eastern regions, dry winds are frequent, but they are not uncommon in the Kuban-Priazov lowland . Dry winds here sharply lower the air humidity and cause greater evaporation, far exceeding the amount of precipitation. For example, in Yeysk evaporation per year is 1200 mm ^[2] .

In most of the province, maximum rainfall occurs in June-July; the end of summer is often arid. This leads to a significant loss of water by evaporation. The rainfall pattern causes water loss through surface runoff. On the Taman Peninsula, precipitation falls mainly in the fall and winter. In spring and early autumn, droughts occur here almost every year.

Due to the complexity of the relief in the Middle Ciscaucasia, climatic conditions are more diverse. Here, differences in humidification associated with orography are observed, and in some areas (the western part of the Sunzhensky ridge, laccoliths of the Cavminvod, especially high-altitude climatic zonality, more often it rains, snow falls deeper and frosts are stronger ^[4] .

The climate of the Tersko-Kuma lowland is drier and more continental, winters are colder and harsher, summers are hotter. The annual temperature amplitude reaches 30 degrees. The average January temperature in the west is from −5 to −7 degrees, in the Kizlyar region –2.5; July - up to 25-26 degrees. The maximum rainfall occurs in the first half of summer - June-July. Summer precipitation falls in the form of showers and water quickly flows through the stock troughs and valleys into lake-shaped troughs and salt marshes, without having time to seep into the ground. In summer, long dry winds are frequent, in the spring and summer dry winds blow at a speed of 12-15 m / s. Summer heat and dryness determine the semi-desert nature of landscapes. The annual rainfall is from 350 mm in the west to 200 mm in the east.

The rivers belong to the basins of the Caspian ( Sulak , Terek , Kuma ) and Azov ( Kuban ) seas. The rivers of the Ciscaucasia, with the exception of the rivers flowing from the Greater Caucasus, become shallow in summer, and partly dry up. Water supply to the Stavropol Territory is partially provided by the Kuban River through the Great Stavropol Canal .

Soil cover

In most of the Western and Middle Ciscaucasia, chernozem soils formed on loesslike loams and clays . The most widespread are the Pre-Caucasian carbonate chernozems boiling from 10% HCl from the surface or within horizon A. They are typically expressed on the Kuban-Priazov lowland, are also common on the northeast of the Prikuban inclined plain, the western and north-western slopes of the Stavropol Upland, the Chechen Plain .

The thickness of the humus horizons of the Ciscaucasia carbonate chernozems is significant, the color is grayish, brownish, due to the relatively low humus content (5-6%). A high level of carbonates is characteristic, which form felt-like deposits of needle crystals on soil aggregates. The features of these chernozems are associated with climatic and hydrothermal regimes; after heavy rains, often in the first half of summer, the soil becomes wet. In the dry and hot second half of summer, soil moisture with carbonates dissolved in it rises to the surface, when it evaporates, carbonates are released in the humus horizon in the form of thin pseudomycelia. Consequently, the Pre-Caucasian chernozems are secondary carbonate.

Where chernozem soils develop on saline (gypsum-bearing) Neogene and Paleogene clays, solonetzic chernozems are formed. They are found on the slopes of ridges and domed elevations of the Taman Peninsula, in places on the Stavropol Upland - in the upper Kalaus , in the Sengiley basin .

In the northeastern Stavropol Territory, chernozems are replaced by dark chestnut and chestnut , often sunny, soils, in combination with steppe solonetzes . In the south, in areas with high humidity, leached chernozems formed. They are common in the Prikuban inclined plain and on high floodplain terraces in the Kuban valley, in the elevated southwestern part of the Stavropol Upland, as well as in the Kabardian, Ossetian and Chechen plains. In the lower northern sections of the inclined plains, meadow-chernozem soils prevail as a result of meadow alluvial soils .

Under forests in forest-steppe regions, podzolized (degraded) chernozems, merged chernozems (soils of heavy mechanical composition, close to dark gray forest soils ), dark gray and gray forest soils have formed . The gray mountain forest soils of mineral water lacollites, according to a number of signs, approach brown mountain forest soils.

In the river valleys, meadow-alluvial and meadow-bog soils are developed. The Kuban delta is characterized by hydromophic boggy and meadow-bog soils, in the coastal areas - solonchak soils.

In the Terek-Kum lowland, the basis of the soil cover is light chestnut, partly solonetzic soils. Between the Terek delta and the lower reaches of the Kuma there are brown sandy loamy soils, usually solonetzic (near Caspian serozems). They are carbonate from the surface and in the upper horizon contain only 1% humus. These soils are combined with solonchak and meadow-solonchak soils. In the Tersko-Kumsky sandy massif, soil salinization is usually not observed and the soil-forming process proceeds according to the steppe type. Here are presented all the stages of development of sandy light chestnut soils - from loose sands to deeply humus in the most overgrown areas.

In the Terek and Sulak deltas, marshy and saline soils are distributed to varying degrees. The main massif consists of marsh soils of floodplains in a complex with meadow and estuary salt marshes.

Flora and fauna

The predominant types of vegetation in the Ciscaucasia are steppe and semi-desert formations. Currently, the steppes of most of the territory are plowed up. Some sections have been preserved in rugged elevated areas, in depressions or on slopes, and occasionally there are sections of virgin land. In the steppes confined to the Ciscaucasia carbonate chernozems, the main edificators are feather grass ( Stipa lessingiana , Stipa capillata , Stipa ucrainica , Stipa tirsa ), as well as fescue ( Festuca valesiaca ), comb keleria ( Koeleria cristata ). Among the abundant forbs there are the most mesophilic species , such as common meadowsweet ( Filipendula vulgaris ), narrow-leaved peony ( Paeonia tenuifolia ), spring adonis ( Adonis vernalis ), green strawberries ( Fragaria viridis ), and forget-me-not forest ( Myosotis sylvic and moreyl sylvic - shaggy sunflower ( Galatella villosa ), noble yarrow ( Achillea nobilis ). There are also species of Caucasian origin - Bleached Psefellus ( Psephellus dealbatus ). In some depressions, thickets of steppe thorns ( Prunus stepposa ), steppe almonds ( Amygdalus nana ), and soft caragana ( Caragana mollis ) are found ^[5] . On the eastern slope of the Stavropol Upland, these steppes turn into fescue-feather grass, then to fescue and, finally, to fescue-wormwood dry steppes, occupying the most arid northeastern part of the Middle Ciscaucasia.

Meadow steppes are confined to leached chernozems of forest-steppe regions, representing the most mesophilic version of the steppe with a lush, almost closed grass stand of a rich species composition with a large participation of dicotyledons , which in some places prevail over cereals . Of the ancient cereals, feathery feather grass ( Stipa pennata ) and timothy steppe ( Phleum phleoides ) are typical, coastal rump ( Bromopsis riparia ), and other southern cereals ( Briza elatior ). On the western slopes of the Stavropol Plateau, areas of feather grass and fescue steppes with feather grass ( Stipa capillata ) and Ukrainian feather grass ( Stipa ucrainica ) are found, feather grass and feather grass steppes from feather grass feather ( Stipa capillata ) and common beard ( Bothri ) are widespread on the gravelly slopes. involving Crimean wormwood ( Artemisia taurica ) and Marshall wormwood ( Artemisia marschalliana ) ^[5] .

In the forest-steppe lowland plains, the steppe occupies mainly plateau spaces, broad-leaved , mainly oak forests , grow in depressions and valleys . The remains of forest plains of the flat forest-steppe have been preserved along the floodplain terraces of the Kuban valley and on the Prikubansky inclined plain, where, however, the high-trunk forests are mostly replaced by shrubbery and light forest ^[2] . In the forest-steppe of the southwestern part of the Stavropol Upland, broad-leaved forests occupy valleys and beams, often rising along steep slopes to the upper level of the watershed trapezoidal plateaus (vicinity of Stavropol, Strazhiment). These are oak-ash-hornbeam forests with an admixture of maple , elm , pear , apple tree , dogwood . In the upper reaches of the beams and on the plateau there are relict sections of beech forest from Fagus orientalis

Broad-leaved oak forest grows in the western part of the Sunzhensky ridge, on the northern slope. In the middle part of the ridge and on the southern slope, small islands of the forest are in beams.

Floodplain forests stretch along river valleys. The Kuban forests consist of Salix alba , Populus alba , Populus nigra , Ulmus minor , Fraxinus excelsior , Alnus glutinosa , Alnus incana , Kuma forests from Ulmus minor , Acer campestre , Salix alba , Populus canescens , Quercus robur , as well as Vitis sylvestris .

Aquatic and marsh vegetation is most developed in the Kuban delta. Four types of vegetation are found here: estuary, including species with floating leaves ( Trapa maeotica , Nuphar luteum ); delta swamp marshes, which are reed beds; meadow-bog and meadow vegetation; saline with the dominance of various solyanka ^[2] . Littoral vegetation is formed by the species Crambe maritima , Verbascum pinnatifidum , Cakile maritima , Eryngium maritimum , etc., which are usual for sea coasts ^[5] .

Растительный покров Восточного Предкавказья — это преимущественно полынно-злаковые, полынно-типчаковые сухие степи на западе и полупустыни в центре и на востоке ^[6] . Выделяется степная растительность Терско-Кумского песчаного массива среди полупустынной. В песках встречается много кустарников ( Tamatix ramosissima , Calligonum aphyllum ), псаммофиты ( Leymus racemosus , Agriophyllum arenarium и др.). Весной на песчаном массиве развивается эфемерная растительность , где доминируют Poa bulbosa , Anisanta sterilis и др.

Полыни и солянки занимают большие пространства в дельте Терека и Сулака, давая все переходы от солончаковых лугов к полынно-солянковым пустынным группировкам. Обводненные участки покрыты зарослями тростника и других влаголюбивых растений, встречается древесно-кустарниковая растительность с Elaeagnus angustifilia , видами Tamarix и др. На Каспийском побережье часто встречаются дюны , поросшие Tamarix ramosissima .

Западному и Среднему Предкавказью свойственна степная фауна, связанная со степями основной части юга Русской равнины : малая белозубка ( Crocidura suaveolens ), обыкновенный ёж ( Erinaceus europaeus ), барсук ( Meles meles ), перевязка ( Vormela peregusna ), степной хорёк ( Mustela eversmanni ), малая ласка ( Mustela nivalis ), обыкновенная лисица ( Vulpes vulpes ), волк ( Canis lupus ), из грызунов обыкновенный хомяк ( Cricetus cricetus ), хомяк Радде ( Mesocricetus raddei ), обыкновенная полёвка ( Microtus arvalis ), большой тушканчик ( Allactaga jaculus ), заяц-русак ( Lepus europaeus ). Из птиц характерны степной жаворонок ( Melanocorypha calandra ), полевой жаворонок ( Alauda arvensis ), обыкновенный перепел ( Coturnix coturnix ), серая куропатка ( Perdix perdix ), журавль-красавка ( Anthropoides virgo ), дрофа ( Otis tarda ), стрепет ( Tetrax tetrax ), каменный орёл ( Aquila rapax ), курганник ( Buteo rufinus ) и др., из рептилий степная гадюка ( Vipera ursinii ), каспийский полоз ( Dolichophis caspius ), ящерицы .

В Восточном Предкавказье фауна представляет смесь степных и пустынных видов, она сходна с фауной пустынь и полупустынь Средней Азии. К степным видам относятся малый суслик , большой тушканчик , гигантский слепыш ( Spalax giganteus ), черноватый хомячок , серый хомячок ( Cricetulus migratorius ), общественная полёвка ( Microtus socialis ), обыкновенная слепушонка ( Ellobius talpinus ), заяц-русак , сайгак ( Saiga tatarica ). К полупустынным животным принадлежат ушастый ёж ( Hemiechinus auritus ), корсак ( Vulpes corsac ), земляной зайчик ( Allactagulus acoution ), мохноногий тушканчик ( Dipus sagitta ) и др. Из пресмыкающихся характерны ушастая круглоголовка ( Phrynocephalus mystaceus ), степная гадюка , песчаный удавчик ( Eryx miliaris ). В тростниковых и кустарниковых зарослях Терека и Сулака встречаются дикий кабан ( Sus scrofa ), шакал ( Canis aureus ), камышовый кот ( Felis chaus ). В плавнях много болотной и водоплавающей птицы.

Западное и Среднее Предкавказье — важный земледельческий район, в Восточном Предкавказье расположены полупустынные пастбища . Во многих районах Предкавказья известны нефтяные ( Русский Хутор , Малгобек-Вознесенское и др.) и газовые ( Северо-Ставропольское , Майкопское , Ленинградское и др.) месторождения.

На территории Предкавказья находятся Южный и Северо-Кавказский федеральный округ . В Предкавказье почти полностью расположен Ставропольский край , северо-восточная часть Краснодарского края и Адыгеи , а также юго-западная часть Ростовской области и северные равнинные районы Карачаево-Черкесии , Кабардино-Балкарии , Северной Осетии , Ингушетии , Чечни и Дагестана .