GLACIERS By: Danny O’Keefe

QUICK FACTS ON GLACIERS 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. In the United States, glaciers cover over 75,000 square kilometers, with most of the glaciers located in Alaska. 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. The land underneath parts of the West Antarctic Ice Sheet may be up to 2.5 kilometers below sea level, due to the weight of the ice. North America's longest glacier is the Bering Glacier in Alaska, measuring 204 kilometers long. The Malaspina Glacier in Alaska is the world's largest piedmont glacier, covering over 8,000 square kilometers and measuring over 193 kilometers across at its widest point. The Antarctic ice sheet has been in existence for at least 40 million years.

WHAT IS A GLACIER Glaciers are made up of mostly fallen snow over long periods of time. When the snow stays there for long periods of time the snow will eventually turn into ice. New layers of snow will bury previous layers and the snow will become very compact. This causes great compression on the compacted snow, forcing it to re-crystallize. When this happens small grains are formed causing air pockets to get smaller, and in result the snow will become more dense. In most cases this will take hundreds of years to happen. Glaciers depend heavily on precipitation –Snowfall –Freezing rain –Avalanches

WHY GLACIERS MOVE Glaciers are unique because they have the ability to move, some moving extremely slow while others can move up to 10 meters in one day. The Hubbard Glacier in Alaska was found moving at a speed of 10 meters per day in 1986 Glaciers needs to accumulate enough snow in order to gain enough weight to start moving. Glaciers move by internal deformation and by sliding at the base. Internal deformation occurs when the weight and mass of a glacier causes it to spread out due to gravity.

Why Glaciers move cont.. When a glacier comes to an end it will begin to retreat. Retreating in glaciers is not the process where the glacier physically moves backwards against gravity, but when the glacier starts to melt or ablate. During the Ice Age glaciers covered about 30% of the earth’s surface, and today it only covers about 10% due to retreating. Today we can see traces of retreating or scars on vegetated hillsides.

Pros on Glaciers Glaciers Provide Drinking Water Glaciers Irrigate Crops Glaciers Help Generate Hydroelectric Power

Cons on Glaciers Glaciers cause flooding Glaciers cause avalanches The Threat of Icebergs- THE TITANTIC