Glaciers

1. Glaciers

2. What is a glacier? It is a large body of continuously accumulating ice and compacted snow, formed in mountain valleys or at the poles, that deforms under its own weight and slowly moves It is actually a moving river of ice! Synonyms:ice floe, iceberg, ice field, icecap, ice sheet, glacier

3. Glaciers are made up of fallen snow that, over many years, compresses into large, thickened ice masses. Glaciers form when snow remains in one location long enough to transform into ice. What makes glaciers unique is their ability to move. Due to sheer mass, glaciers flow like very slow rivers. Some glaciers are as small as football fields, while others grow to be over a hundred kilometers long.

4. 2 Kinds of Glaciers

5. Where can glaciers be found? Presently, glaciers occupy about 10 percent of the world's total land area, with most located in polar regions like Antarctica and Greenland. Glaciers can be thought as remnants from the last Ice Age, when ice covered nearly 32 percent of the land, and 30 percent of the oceans. An Ice Age occurs when cool temperature endure for extended periods of time, allowing polar ice to advance into lower latitudes. For example, during the last Ice Age, giant glacial ice sheets extended from the poles to cover most of Canada, all of New England, much of the upper Midwest, large areas of Alaska, most of Greenland, Iceland, Svalbard and other arctic islands, Scandinavia, much of Great Britain and Ireland, and the northwestern part of the former Soviet Union.

6. Presently, 10% of land area is covered with glaciers. Glaciers store about 75% of the world's freshwater. Glacierized areas cover over 15,000,000 square kilometers. Antarctic ice is over 4,200 meters thick in some areas. During the last Ice Age, glaciers covered 32% of the total land area. If all land ice melted, sea level would rise approximately 70 meters worldwide. Glacier ice crystals can grow to be as large as baseballs. North America's longest glacier is the Bering Glacier in Alaska, measuring 204 kilometers long. Glacial ice often appears blue when it has become very dense. Years of compression gradually make the ice denser over time, forcing out the tiny air pockets between crystals. When glacier ice becomes extremely dense, the ice absorbs all other colors in the spectrum and reflects primarily blue, which is what we see. When glacier ice is white, that usually means that there are many tiny air bubbles still in the ice. In Washington state alone, glaciers provide 470 billion gallons of water each summer. Almost 90% of an iceberg is below water--only about 10% shows above water. Have you ever heard of the term “just the tip of the iceberg”? The Antarctic ice sheet has been in existence for at least 40 million years.

7. U Shaped vs. V Shaped Valley

8. Glacial Erosion Valley glaciers erode in two different ways, by pluckingand abrasion. Pluckinghappens when materials are picked up by the moving glacier and moved from the place that it has been for centuries. The materials that are picked up by plucking are either laying on the ground, or they are broken or fractured off of the side of a mountain. During abrasion smaller particles act like large pieces of sand paper and cause grooves to be carved into the land. The surfaces of rocks are polished as the glacier moves across it.

9. Eratics Eratics are boulders that the glacier has carried along with it as it moved. Some eratics fall onto a glacier during an avalanche and ride on the top of the glacier until it melts. When the glacier melts it leaves the boulder far away from where it first fell. Sometimes smaller boulders that are already on the ground when the glacier passes, and the glacier just picks it up and moves it too.