Glacial and Sea Level History of Chukotka Peninsula

The Val'katlen Suite at its type section at the mouth of the Enmelen River records the youngest high-sea stand of the last interglaciation on Chukotka Peninsula. Marine deposits and glacial diamicton stratigraphically below the type section record, respectfully, the peak of the last interglacial (oxygen-isotope substage 5e) and rapid glacierization of the coastal mountains probably during substage 5d or 5b. Correlative deposits recording a similar sequence of intra-stage 5 events, but once thought to be of early and middle Pleistocene age, include the Upper and Lower Pinakul' Suite at Cape Pinakul' and marine deposits near the Nunyamo River on the Gulf of Anadyr, based upon amino acid analyses, biostratigraphy, and supporting geochronology. These deposits enclose warmer than present faunas and floras comparible to last interglacial Pelukian marine deposits found along the coast of Alaska.

The last major advance of glacial ice from Chukotka Peninsula across Anadyr Strait and onto St. Lawrence Island was likely initiated during the later part of stage 5 based on our reinterpretaion of the stratigraphy at Cape Pinakul' and near the Nunyamo River. Chukotkan ice probably reached St. Lawrence Island sometime during oxygen-isotope stage 4. Marine deposits at Val'katlen and the Nunyamo River may be correlative with the Flaxman member of the Gubik Formation in Alaska.