GEOMORPHOLOGY AND THE FORMATION HISTORY OF GLACIAL MATERIALS OF THE EV’VAYAM RIVER VALLEY (KORYAK HIGHLANDS)<a href="#FN2"><sup>2</sup></a>

Abstract

Based on the interpretation of satellite images and field observations, three moraines of different ages and morphology were identified in the valley of Ev’vayam River. The oldest, poorly preserved and significantly eroded moraines are located in the lower reaches of the Ev’vayam River near the Bering Sea coast. A well expressed in relief complex of younger moraines consisting of three better-preserved moraine ridges (45, 62–72 and 87–95 m a. s. l.) with thin soil cover is distinguished in the middle reaches of Ev’vayam River. The youngest moraines are found in the upper reaches of the Ev’vayam River Valley at elevations of 240–320 m a. s. l., where they form longitudinal ridges, or “tongues”. Based on the preservation degree, morphology and size of the investigated glacial complex, and published data on adjacent areas, the glaciation of the territory had a mountain-valley character. The glacier apparently reached its maximum size at the beginning of the Late Pleistocene, when it moved beyond the valley of the Ev’vayam River to the coast. The moraines in the central part of the valley and in its upper reaches were formed by much smaller glaciers during the end of Late Pleistocene. The recharge area of glaciers during this period was limited to a series of glacial cirques and kars in the central part of Pylgynskiy Range. Currently, small glaciers are present in cirques at elevations from 410 m to 720 m a. s. l., and continue to form modern moraines.