Lesson 13:Louise Arner Boyd and Glaciers

As a glacier moves, it changes size and shape. Deep cracks
or cuts in the glacier can also form. These deep cuts are called
crevasses. A crevasse can be very dangerous for those who dare
to climb a glacier.
How Glaciers Change the Landscape
Glaciers have caused many different types of landforms
in the United States. About 10,000 years ago, a huge ice sheet
covered about half of the northern United States. When these
massive glaciers gradually melted and moved northward, they
left a vastly changed landscape.
For example, glaciers can cause lakes to form. The five
Great Lakes — Lake Erie, Lake Ontario, Lake Huron, Lake
Superior, and Lake Michigan — were created by glaciers. So
were the Finger Lakes in New York and Lake Champlain, the
latter which divides New York and Vermont. Minnesota is
known as the “Land of 10,000 Lakes.” Glaciers created most
of those lakes, too! Large valleys, such as Yosemite Valley in
California, were also formed by glaciers.
Glaciers can leave a lot of debris behind, because they are
so large and because the force of their movement is so great.
This debris is called a moraine. Moraines are usually made up
of a mix of soil and rocks. Some of the rocks are large boulders!
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