Once
fast ice (sea-ice frozen in situ and attached to the coast) has become established, the patterns of
the earlier pieces disappears. The tide still rises and falls however
meaning that the sea surface expands and shrinks slightly as it does so.
Tide cracks are a result of this movement (as ice is not known for its elastic
properties) they are formed when the ice moves apart, they close again
when the tide falls. A tide crack is often many miles long, in this case
stretching for around 5 miles (8 kilometers), but never more than about
18", 45cm wide between Signy and Coronation Islands in the South
Orkneys group. Tide cracks are valuable resources for wild-life as they
provide a region where birds such as snow petrels can fish through for
krill and also as a breathing hole for crab eater and Weddell seals.
Paul
Ward - Pentax equipment, 50mm lens, 35mm film, K64.
This picture may not be copied or used in any manner without
prior written permission.
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