Monday, August 15, 2011

A Little About Glaciers

Something I have found interesting as of late are glaciers and the effects they played upon the land.  So here is a little bit to share with you of what I have learned about them.

While we were volunteering at Ottawa NWR in Ohio, we took a trip over to Kelly's Island to see Glacial Grooves State Memorial.

These are some of the best examples of Glacial scarring we have seen.

During the last Ice Age 25,000 years ago, the ice sheet covered all of Maine to a depth of 1.5 miles.  The weight pushed the Earth's crust downward over 500'.

With rising global temperatures, the southern margin of the ice sheet began to retreat across the Gulf of Maine.

Just after the glacial retreat much of Maine was a treeless tundra that housed large animals, such as wooly mammoths.  Today, Maine is the most forested state in the U.S.

Maine's diverse geologic landscape was created by these vast sheets of glacial ice melting and moving in a south easterly direction leaving behind moraines, deltas, and eskers.  This North American continental glacier is called the Laurentide Ice Sheet.

Cadillac Mountain, in Acadia N.P., was possibly the first to emerge from the ice about 17,000 years ago.  It was shaped by glacial abrasion and quarrying beneath the ice sheet.  There are many places where you can see these glacial grooves.

The term moraine is sediment deposited directly from a glacier.  It is a random mixture of rock and mineral fragments ranging from clay to boulder size.  This material is also called till.

Eskers are ridges of sand and gravel deposited in tunnels that formed at the bottom of the ice sheet.  During the ice retreat, the tunnels were clogged with sediment.  These tunnel fillings that were left behind are called esker ridges.

Deltas are large, flat-topped bodies of sand and gravel that washed into the sea at the edge of the glacier.  The sand and gravel were deposited in such large quantities that they eventually built up to the ocean surface and became full-fledged deltas.  The sandy soils on eskers, deltas, and moraines are favorable for growing blueberries.

From Acadia N.P. to the east south of Calais is an interesting trail of Maines Ice Age where there are 46 stops to see and learn about the last Ice Age.

We had this picture on before, but this is an example of a moraine and what the glaciers left behind.  A sight like this is not hard to find, boulders left scattered around here in the great state of Maine. 

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