Process environments on modern and raised beaches in McMurdo Sound, Antarctica

Abstract

Modern beaches in McMurdo Sound can be divided into three process regimes. Beaches on Ross Island (eastern McMurdo Sound) are characterised by normal marine processes with little ice modification. On ice-bound western McMurdo Sound, coastal orientation is of paramount importance. Ice thrust features are prominent on south facing beaches, which are open to the predominant wind direction, while more marine dominated beaches occur on north facing coasts where sea ice is blown offshore. In contrast to the modern beaches, raised beaches are similar all around McMurdo Sound. These are inferred to be storm ridges. The size and frequency of the ridges is a product of the local wave climate. The number of raised beaches at any site is a useful indicator of the paleo-wave climate. More ridges occur in sheltered south facing locations, because they are more protected from open marine conditions, than on beaches in ice-free or north facing locations. This is important for rebound reconstructions in the Sound as marine limits have been incorrectly identified in the past.