Signy Island

Signy Island (lat. 60° 43' S, long. 45° 38' W) is one of the southernmost and smaller members of the South Orkney Islands, which lie in the South Atlantic Ocean on the southern arm of the Scotia Ridge. It has a total surface area of about 20 km2, a greatest length (from north to south) of 8 km, a maximum width of 5 km and a highest elevation of 280 m. The north point of the island is only 1.5 km distant from Coronation Island, largest of the South Orkney group. In outline Signy Island is roughly triangular (figure 1) but the coastline, which is mostly cliffed, is indented by bays, and projects in numerous narrow headlands. Along the western coast there is a strip of lowland which shows prominent terraces, probably of marine origin, at the 30 to 60 and 80 to 100 m range. On the north-east and south-east there are other lowland areas with a more mammillated topography. The uplands of the island are roughly cruciform in plan, the main axis running NNE-SSW from Robin Peak to Snipe Peak on Moe Island and the east-west arm extending from Jebsen Point through Garnet Hill to Rusty Bluff. All these summits are flat topped and reach a rather uniform elevation of 200 to 280 m. The topography as a whole is rugged (figures 2, 3, plate 15) and reflects the combined influences of structure, marine erosion and glaciation, the latter being dominant. There are numerous cirques about the margins of the highland, and extensive moraine and outwash deposits on the lower ground. Locally, as in Three Lakes Valley and inland from Cummings Cove these deposits mask the underlying relief of the bedrock surface.

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