Prince of Wales Fort National Historic Site of Canada

Isostatic Rebound

For many years it was thought that the dry cove was a result of the phenomenon known as isostatic rebound. This situation describes the gradual rising of land elevations as it springs back after thousands of years of being crushed under the weight of continental glaciers. The west coast of Hudson Bay is known as one of the more dramatic areas of isostatic rebound where the land still rises at a rate of a meter per century. This is especially noticeable in the flat lowland areas of the coast. However, at Sloop Cove, mooring ships in 1750 would have involved a situation where the daily water level was, at most, less than 3 m higher than today. This situation would have resulted in a large pool in the cove where the Centre was about 1 m deep and most of the pool was 50 cm or less - hardly enough for boat mooring. However, even at an increase of only 2 m, the cove becomes an almost perfect dry dock. At high tide, there is enough water to easily drag the boat into the mouth of the cove and past the breakwater and natural island. Then the boat can be manhandled through a shallow, salt water pond to the location desired. Once into the cove, there is little chance of damage from ice or storms.

Sloop Cove water levels
Sloop Cove water levels
© Parks Canada/ PWF Collection

Above, a recently constructed contour map has been used to help picture what the cove would have looked like at various times in the past. Notice that, at 3 m , the breakwater along the east edge was virtually totally underwater. As this is a man made feature, it is likely that it was constructed to the edge of the water. The 2 m line appears to be a more reasonable level. That level would also show the island as a decent sized outcrop, not just a piece of rock surfacing out of the water.