Mountains lie on the border of the East European Platform and the Mediterranean Geosynclinal Province. Their geological structure is the result of successive periods of sedimentation, orogenesis, and denudation. The basic pattern in the structure of the Ukrainian Carpathians is their distinct division into longitudinal structural-lithological zones. The mountains were principally formed in the Tertiary period and, therefore, Cretaceous and Lower Tertiary rock formations are most widespread in the Carpathians. The older Paleozoic and Precambrian rocks are quite rare and are found mostly in the
Mountains and the
Mountains, which are part of the
Upland. Upper Cretaceous and Paleogene deposits appear in dislocated layers of flysch—interbedded sandstones, marls, and schists. Late Tertiary strata are common in Subcarpathia and
Transcarpathia. Quarternary formations such as glacial deposits, alluvial deposits, and
loess in the depressions are widespread.
The tectonic structure of the Ukrainian
Mountains is complex and is still being investigated by geologists. Generally, however, the structure is characterized by zonation and nappes. The
Mountains were formed during the Alpine orogeny in the Tertiary period. Prior to that, from the end of the Paleozoic to the Cretaceous period, mountains of the Hercynian orogeny (late Paleozoic era), known as the Protocarpathians, existed in their place. In the Cretaceous and Lower Tertiary periods the Protocarpathians were destroyed and were replaced by geosynclinal depressions filled with seawaters. The
Rakhiv Mountains and isolated cliffs (klippen) are remnants of the ancient mountains. In the geosynclines flysch was deposited to a depth of 5,000–7,000 m. In the Upper Tertiary period the present mountains rose at the site of the geosynclinal depressions. Their formation was accompanied by violent volcanic effusions. The contours of the Carpathians were formed in the first half of the Miocene epoch. In the middle of the period the Carpathians underwent partial peneplanation, which was interrupted by uplifting followed by peneplanation again. The present relief of the mountains is the result of the two peneplanations, which produced large, flat surfaces and terraces at several altitudes. During the Quarternary period there was some glaciation of the Carpathians in the Riss and Würm ages. Transverse dislocations, which cut across the structural zones and frequently provide a path for
rivers, play an important role in the geological structure of the Ukrainian Carpathians.
The climate of the Carpathians is determined by the climate of the adjacent plateaus, the height of the mountains, and the relief. Seasonal variations (which also affect the Danube Lowland) in barometric pressure from the winter maximum to the summer minimum have an important influence. The mountains protect southern
Transcarpathia from the flow of cold air from the north. However, warm air masses from the Mediterranean Sea and the Atlantic Ocean bring cyclones and heavy rainfall to the southern and western slopes. The July temperature varies with altitude from 20°C at the southern edge of the Carpathians and 18°C in the north to 6°C on the highest peaks. The variation is smaller in winter—from -3°C to -10°C. The number of days with temperatures above 0°C fluctuates between 290 and 100 per year, and the number with temperatures above 10°C varies from 180 days in the south to 80–100 days at the upper limits of
grain cultivation and to 50 days in the lower meadow belt. Annual precipitation varies from 600 to 1,600 mm and is usually 900–1,200 mm, depending on altitude and local conditions, such as the position of the slopes. The basins of the upper Teresva River and
River receive the largest amount of precipitation, while the intermontane depressions are relatively dry. The southern slopes get 100–200 mm more precipitation than do the northern slopes at the same altitude. Most of the precipitation occurs in June and July; the least, in January and February. In general, almost two-thirds of the precipitation comes in the warm half of the year; hence summers are quite cloudy, and winters are sunny.