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Figure 19.21 Sinuous form of an esker is seen in this aerial
photograph Eskersare sinuous ridges of glacio-fluvial material that form in
tunnels in an ice sheet . The sides of the tunnel act as part of the
channel for a melt water stream. As the glacier recedes, the support for
the stream is removed and the stream deposits its load into a long
ridge-like form. Eskers are good sources for sand and gravel, and many
of them have been destroyed by mining for these materials.
Drumlins are stream-lined hills that appear separately or in "swarms". Their formation is not well known but form by the deposition of till. As the ice rides over the till it is smoothed into an inverted spoon-shaped feature. The steep side faces the direction the ice sheet came from while the more gentle slope of the tail points toward the direction of ice flow.
Kames are steep mounds or conical hills built by the deposition of stratified drift in or around ice. Some kames form in holes in the ice where sediment accumulates. A mound of glacial drift is left behind once the ice melts.
Kettles are pits in the surface that may or may not be occupied by water. They form when an isolated block of ice is surrounded by till or stratified drift. After a period of time the ice block melts away leaving behind a hole in the surface. Kettles are often found on outwash plains or embedded in moraines (hence the name for Kettle Moraine State Forest in Wisconsin). Go here to view kames and moraine topography in the Northern Unit of Kettle Moraine, Wisconsin (Caution - 1.13 MB QuickTime file).
Figure 19.25 "Moulin, Kame, and Esker Formation" |
