by Effie Moore Salem

Created on: July 28, 2008   Last Updated: November 11, 2010

The Great Glaciations, as distinguished from glaciations as we know them today, is what changed the topography of the North American continent. As an example, during the time of the Lewis and Clark expedition, the land mass and the water ways would have been different from that of the time of the Great Glaciations period. These were only one of the first of many such mountain and earth movers. Ever so slowly they change the shape of the earth as they melt and reform. It's still happening today but ever so slightly.We do have statistics that show how glaciers are melting and how this is raising the water levels, but only that that, the changes taking place are so subtle and so slow, they are unobservable.

Glaciers are old ice formations that have been with us for 4.6 billion years and possibly beyond. They exist in the frigid areas of the earth and enlarge or diminish according to the weather. The oldest of the three classifications, geologist say, date back to the Precambrian period, the time the earth was forming and primitive life began.

The second era occurred around three million years ago; the third period dates from 1.6 million years and ended 10,000 years ago, geologist say. So, armed with these facts, where did the glaciers that are melting rapidly today and raising water levels come from? They come from the warm glaciers in ice capped areas and in other extremely cold arctic places that are slowing warming.

Glaciers make up about 70% of the fresh water of the earth. Most ice accumulations are in Antarctica and Greenland and other in frigid areas of the earth. It is good that we have much of our water in frozen storage. if this was not so, then most of the earth, as we know it today, would be under water. It makes sense to understand that if glaciers contain 70% of the earth's water, and they were to melt, the oceans would rise 70%.

Another way of looking at the amount of stored water is to know that all the water that the world started out with is here today. Some is frozen and some is not. Then the next obvious question we should ask is what is causing glaciers to melt or to freeze. The activity of the earth and what happening in the atmosphere and how much of the action on earth is warming up our space, or cooling it down. Both of opposing situations, seem to run, when studied over a long period of time, seem to have been in cylces.

In fact, what is happening now with our warming trend could only be a warm cycle beginning. Yet, before we relax and

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