Esker
Natural Resources Canada image (fair use policy)
The low ridge winding across the landscape of northern Manitoba, Canada, is a classic esker. When a great ice sheet covered central North America, about 10,000 years ago, a stream of meltwater ran beneath it at this location. The abundant sand and gravel, fresh-made under the glacier's belly, piled up on the streambed while the stream melted its way upward. The result was an esker: a ridge of sediment in the form of a rivercourse.
Normally this kind of landform would be wiped out as the ice sheet shifts and the meltwater streams change course. This particular esker must have been laid down just before the ice sheet stopped moving and began to melt for the last time. Similarly, the small lakes to the right in this photo mark where the last masses of ice sat while meltwater laid sediment down all around them. They're called kettles.
Fossils
Geologic Features and Processes
Glaciers and Ice
Landforms
Minerals
Rocks
Geology and Society
