Granulometry of pebble beach ridges in Fort Williams Point, Greenwich Island, Antarctic Peninsula; a possible result from Holocene climate fluctuations

We present a granulometric study of emerged pebble beach ridges in the Fort Williams Point, Greenwich
Island, Antarctic Peninsula. We studied 8 beach ridges from the shore up to 13.5 m above current sea level. The beach
ridges are made of volcanic material from the surrounding relief, but also include glacially transported gneiss and
granodiorite pebble and cobble. Based on granulometric distribution analysis of 2100 samples from 39 locations we
identified evidence of 4 sequences of 1 to 3 ridges. Most of the material seems to be reworked from a till. Pavement
formation by iceberg between the sequences of beach ridges suggests periods of lower temperature. The interpretation
suggests that sequences of beach ridge construction formed during warmer periods of the late Holocene. This occurs in
the framework of an isostatic postglacial uplift allowing the progressive mobilization of periglaciar material.