Early and middle Holocene fossil-bearing marine sediments from Potter Peninsula, King George Island (South Shetland Islands, Antarctica)

These data allow to reconstruct part of the Holocene history of sea level (Fig. 4) and constrain the age of early-to-middle Holocene environmental changes on the Potter Peninsula coastal area (Table 4): The early Holocene withdrawal of glaciers from Potter Cove (south-west King George Island) acompanied by a sea level high stand allowed marine sedimentation in an open fjord c. 9600 years ago (Section 1). This high stand of sea level may be related to the 10-9 ka BP marine transgression that drowned the Maxwell Bay coasts (south-west King George Island) (Fig. 1) down to 25-30 m depths.

After a short-live episode of glacial-marine sedimentation, an early-middle Holocene (c. 9600-7500 yr BP) lowering of the relative sea level allowed marine beach sediments to be deposited on the fjord sediments (Section 1). The glacial till that covers the marine beach sediments (Section 1) is thought to be deposited during the middle Holocene (post-7500 yr BP) glacial advance named "Pu nta Baliza" (PBGA: Birkenmajer 1998).

The thin coat of raised marine gravels, which covers PBGA reworked glacial till at c. 3.77 m a.s.l. (Section 1), suggests that probably during the culmination of PBGA the sea penetrated well into the coastal area of Potter Peninsula. Additionally the raised marine beach sediments 14.7-16.7 m dated to c. 5500 yr BP (Section 2), confirm that the sea drowned the coasts of Potter Peninsula down c. 10-12 m depths during middle Holocene periods of open marine water conditions.