On the Geomorphology and Past Glaciation of Storöya, Svalbard

Storöya is a 50 km2 large island in northeastern Svalbard. Its southern half is covered by a cold-based ice cap, while the remaining part (22 km2) is non-glacierized. Most of the latter area is covered with regolith.The marine limit was found at 66 m a.s.l. Above this elevation the regolith has a non-washed character but still contains rounded boulders of the same type as below the marine limit. As many of these rounded boulders are made of metamorphic or red magmatic rocks found on Nordaustlandet, while the bedrock of Storöya is gabbro and quartz diorite, the regolith is considered to be old beach material transported as till to the island.Here and there bedrock crops up through the regolith. These rock exposures lack all glacial sculpture, wherefore the glacier that deposited the till on Storöya must have been cold-based. In analogy with presentday conditions on Austfonna-Sörfonna a warm-based interior of the glacier must have existed on Nordaustlandet.Eight samples of driftwood have been collected. The highest sample was taken from 53 m a.s.l. Extrapolation of the curve to the marine limit shows that deglaciation of Storöya started around 10 000 years B.P. on the northeastern tip of the main hill. The preceeding advance of a partly warm-based glacier from Nordaustlandet is suggested to have taken place during Younger Dryas.During the Holocene epoch Storöyjökulen must have had a smaller area than at present at least between 7200 and 3200 years B.P. and most probably also between 10000 and 7200 years B.P.