Abstract: The object of this research is the organic-mineral deposits of the Late Pleistocene polygonal ice-wedge complex. They are studied in the outcrop of the second terrace, located on the left bank of the Mongatalyangyakha River, 3 km west of the estuary (71 ° 58'60 "N, 75 ° 16'0" E), on the Yavay Peninsula in the north of the Gydan Peninsula. The botanical composition of allochthonous peat in the upper part of the section is dominated by the remnants of Ledum palustre, and in the organic-mineral sediment the remains of Drepanoladus fluitans, Calliergonella cuspidata (or Calliergon cordifolium) are prevalent. A field outcrop study was performed; three wells were drilled. Palynological and hydrochemical diagrams were constructed and the radiocarbon age of the Late Pleistocene polygonal massif was determined. The main conclusions of the study are: 1. The age of the organic-mineral deposits varies from 30,200 to 21,900 years BP. 2. The rate of accumulation of organic-mineral deposits in the Karginsky time at the mouth of the Mongatalyangyakha River is about 0.25mm/year. 3. According to the palynological analysis, three local pollen zones are distinguished.