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Glacial Systems
Figure 19.15 Sinuous form of an esker is seen in this aerial
photograph
(Courtesy Geological Survey of Canada)
Eskers
 are 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.
 Figure 19.16 Streamline profile of a drumlin in Alberta, Canada
(Courtesy Geological Survey of Canada)
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.
 Figure 19.17 Kame in northern unit of Kettle Moraine State Park, WI (Click
image to enlarge)
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.
 Figure 19.18 Kettle lake in moraine. (Courtesy USGS DDS21)
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).
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