1. When Glaciers Roamed the Earth By Sara Hauf

2. Part 1: Glaciers Thousands to million years ago, large masses of ice called glaciers covered the earth. There are two types of glaciers: valley and continental glaciers. A valley glacier is a long narrow glacier that forms when snow and ice build up in a high mountain valley. Continental glaciers are glaciers that cover up much of a continent or large land. They cover 10% of the earth’s surface today.

3. Glaciers form in places where snow falls more than it melts. The snow then compresses into ice. The pressure from the ice compacts and becomes a big mass of snow and ice. Gravity naturally pulls glaciers downhill. When glaciers move and melt, they pick up and drop off sediment called till. Till is made up pieces of rock, shells, and whatever was left on the ground on the earth’s surface. This whole process is called deposition.

4. When glaciers move, they also retreat. As they retreat, they can create earth features such as a moraine, a ridge in the ground caused when glaciers push the push the earth surface creating a bump in the ground. They can also form things called kettle lakes. When glaciers are on the surface of the earth, they can be heavy enough to make a depression. When they melt, water fills the depression to form a lake. Many famous lakes, like the 5 Great Lakes, Walden Pond and Fresh Pond were all formed by glaciers.

5. Part 2: Erosion Glacial movement is a major force of erosion. One major process is called abrasion. Abrasion is when tiny bits of particles called loess, is carried either by water or wind and scratches the surface of rocks or other hard surfaces. There are 3 types of erosion, Erosion by Water, Waves and Wind. These agents are the major sources of erosion, and together, they can even grind down whole mountains.

6. Running water creates many landforms. Erosion by water starts with rain. Runoff is the remaining water that moves over earth’s surface. The impact from the runoff creates grooves in the soil called rills and gullies. Gullies are large grooves or channels. When gullies join together, they form a stream.

7. Part 3: Formations on Earth Glaciers and erosion work hand and hand to form different landforms on earth. Wind pushes out till and sediments called longshore drift to form long narrow “fingers” of land along the coastlines called spits. Spits are found many places along the coast of the United States, like Cape Cod or Long Island. Both were formed by Erosion, and now are homes for many people.

8. When land is eroded, it can form new places from the old places. One example is a drumlin. A drumlin is a low oval mound or hill consisted of glacial till shaped by past glacial action. When the drumlins flood, it creates a new formation called a drowned drumlin. The Boston Harbor Islands were formed that way. Glaciers have done so many things to our earth, and so we should thank them for the new land and homes they have formed for us, even if it happened thousands of years ago.

9. All Sizes | Ferring Strand | Flickr - Photo Sharing!" Welcome to Flickr - Photo Sharing. Web. 04 Nov. 2011.. "Moraine and Three Fingered Jack | Flickr - Photo Sharing!" Welcome to Flickr - Photo Sharing. Web. 04 Nov. 2011.. "Streams and Rivers | Flickr - Photo Sharing!" Welcome to Flickr - Photo Sharing. Web. 04 Nov. 2011.. "Terminal Moraine by Doc Searls in Retreat of Glaciers since 1850, Terminal Moraine on Fotopedia - The Photo Encyclopedia." Fotopedia. Web. 04 Nov. 2011..