_____ Geological structure. The Ukrainian Carpathian 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 Rakhiv Mountains and the Chyvchyn Mountains, which are part of the Maramureş-Bukovynian 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 Carpathian Mountains is complex and is still being investigated by geologists. Generally, however, the structure is characterized by zonation and nappes. The Carpathian 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.