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Glacial Physiography
The Great Ice Age (or
Pleistocene epoch about 8,000 to 1.8 million years ago ) resulted in
glacially formed landforms (glacial physiography). Many
such landforms are located in New England and Massachusetts where we
at Geologic Resources are located. We have taken
pictures of some photogenic features in our vicinity and present
them here. Following are some Ice Age landforms (with
definitions from
Wikipedia).
-
Terminal moraine
- is a
moraine that forms at the end of a
glacier. We now know th at
terminal moraines are created at the edge of the greatest extent of
the glacier. At this point, the debris that has been pushed by the
front edge of the ice is driven no farther, but instead is dumped in
a heap. Because the glacier acts very much like a conveyor belt, the
longer it stays in one place, the greater the amount of material
that will be deposited. The moraine is left as the marking point of
the terminal extent of the ice.
-
Esker - Eskers are long, winding ridges of
stratified
sand
and
gravel which occur in
glaciated and formerly glaciated regions of Europe and North
America. They are frequently several miles in length and, because of
their peculiar uniform shape, somewhat resemble
railroad
embankments.
-
Drumlin - A
drumlin is an elongated whale-shaped
hill
formed by
glacial action. Its long axis is parallel with the movement of
the ice, with the blunter end facing into the glacial movement.
-
Erratic - A
glacial erratic is a piece of
rock carried by
glacial ice some distance from the rock outcrop from which it
came. Erratics can range in size from pebbles to massive pieces.
They can be found miles away from their original location.
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Satellite Image of Cape Cod, Massachusetts, USA
and a portion of Massachusetts adjacent to the cape. Cape
Cod is composed of a terminal glacial moraine that is underlain by
older coastal plain deposits. These deposits are both
weak and unconsolidated and have been reshaped by coastal erosion
and deposition to form the present physiography. Photo provided by NASA and taken from
Satellite. NASA Visible Earth: http://visibleearth.nasa.gov

Esker - On the crest of an esker, Hadwen Park,
Worcester, Massachusetts, USA. The esker is what remains of a
Pleistocene (Ice Age) stream. These features formed on, in, or
under the last Pleistocene ice sheet when it covered what is now the City of
Worcester. The esker probably formed when the ice melted during
the period that the ice sheet retreated northward. This
esker is approximately 2 miles (3.2 km) long. They are generally composed of sand, gravel,
boulders, and cobbles deposited from moving water.
Photo by Flo Bruehl, November 21, 2006.

Beacon Hill, a
drumlin in Boston, Massachusetts, USA is occupied by the Massachusetts capital
building near its crest. The City of Boston and vicinity
contain many drumlins and other glacial features, remnants of the Wisconsin
continental ice sheet during the Great Ice Age (or Pleistocene Era). Photo by Flo Bruehl, June 24, 2007.

Bunker Hill, a
drumlin in Charlestown, Massachusetts, USA is occupied by the Bunker Hill
Monument and Bunker Hill National Historic Park on its crest.
The vicinity contains many drumlins and other glacial features, remnants of
the Wisconsin continental ice sheet during the Great Ice Age (or Pleistocene
Era). Photo by Flo Bruehl, June 24, 2007.
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