Glacial Impact

Throughout the history of the Earth, the world has changed in many dramatic ways. Many of these changes have happened on such large scales that it is hard for some to even comprehend. Entire continents have moved thousands of miles, mountains have risen from the depts of the oceans, and ice sheets have engulfed much of the worlds surfaces. Evidence of all these events can be found, although some of the most interesting are those land forms from glaciations and past Ice ages.

Effects of Glacial Advances

When a glacier advances, there is so much power and pressure behind it that it can literally move mountains. One of the most common examples of this can be seen anywhere a glacier has move over bedrock. When this happens, large scratches or striations are created from the boulders being carried by the moving ice. Another example is known as glacial abrasion and quarrying. This happens when a glacier moves over a hill or mound, scrapes of the top off it, and either accumulates it in its ice mass or deposits it on the other side.

One very visual example of glacial erosion can be seen in any mountain range with glaciers. When mountains form, water flows down forming V-shaped valleys, but once a glacier has moved through the area, these valleys are transformed into U-shaped and it is quite evident.

Glacial advances have also been know to enlarge and deepen preexisting lakes and rivers. When the last Ice Age passed over the Great Lake region, it transformed the lakes forever by making them deeper and totally rerouting the river flowing from them.

The most interesting of all glacial formations are morains and glacial till. This happens when an ice sheet begins the retreat and it deposits all it has accumulated along the way. This is most relevent to us because it what how the entire Seattle/Puget Sound area was created. Glaciers carved their way in, over and around the San Juans and Puget Sound, and when they retreated, it left all it had picked up along the way creating Seattles seven hills.

Evidence of Ice Ages can be seen in all of Canada and most of the Northern U.S. They are interesting land marks which help explain the stories of the past, and will hopefully help us predict these phenomenons for the future.