The Alaskan Arctic Coastal Plain and its submerged extensions to the north and west, the Beaufort and Chukchi continental shelves, are underlain by a broad, low-relief bedrock surface, the North Beringian Marine Abrasion Platform, which dips gently seaward from the Arctic foothills of the Brooks Range northward to the continental shelf break of the Arctic Basin (Fig. 1). During late Cenozoic time the sea repeatedly transgressed and receded across the North Beringian Platform in response to glacioeustatic sea level fluctuations. A thin veneer of unconsolidated, interfingering marine and nonmarine deposits mantles the bedrock surface and records the succession of geologic environments that have prevailed there during the last 3 m.y. All of these unconsolidated deposits are presently assigned to the Gubik Formation, which has a maximum measured thickness of about 60 m onshore, and thickens to perhaps a few hundred meters in places beneath the Beaufort shelf. In this chapter, we summarize and discuss the depositional history of the Gubik Formation and its bearing on the late Cenozoic geologic and climatic history of the Arctic region. The discussion begins with the onshore exposures, which have been studied in detail over many years, and for which a coherent stratigraphic framework has begun to emerge, and then moves to the offshore deposits, which, though thicker and better preserved, have only recently become the target of stratigraphic investigations.

The marine deposits of the Gubik Formation on the Arctic Coastal Plain have intrigued researchers since the early years of this century, when Leffingwell