Glaciers Galore Ice Queen Period 1 Earth Science Honors November 30, 2013 The last Ice Age (Wisconsian) occurred over the last 2-3 million years (1). The Laurentide Ice Sheet last covered New England from about 24, ,000 years ago (1, Fig. 1). Latitude: Ranged from about 60W-120W (2). Longitude: Ranged from about 45N-80N (2). Its maximum area was 5,000,000 square miles (1). It began to retreat about 20,000 years ago, and carved out much of the New England landscape (1). The two main types of glaciers are: 1) Ice Sheets (3, Fig. 2a) 2) Alpine glaciers (3, Fig. 2b). Ice Sheets are larger than Alpine glaciers and tend to cover whole countries or continents. They start at one center point and spread out in all directions (3). Greenland and Antarctica are the main two remaining Ice Sheets on Earth (3). Alpine glaciers are small glaciers and flow downhill through mountain valleys and tend to be narrow in width and very long in length (3). Part of the Hubbard Glacier in Alaska is thought to be an Alpine glacier (3). Glacial Ice forms from the accumulation of snow over time (Fig. 3). Scientists determine the age of glaciers by dating the organic matter found in the sediments (4). Scientists know a glacier has retreated or advanced by setting markers along the glaciers. Over time as the glaciers move so will the markers (3). Depending on how much the markers move in a set period of time will the determine the speed (3) Introduction Methods Conclusion Figure 1. Laurentide Ice Sheet (6). I used the internet and the Earth Science text book to research the Laurentide Ice Sheet, how Alpine glaciers and Ice sheets form, all of their parts and their impact on the environment. Objective To identify and understand the two main types of glaciers. Describe how glaciers form. Provide examples and descriptions of glacial features. Determine how glaciers have and will impact the earth. There are 2 types of glaciers, Alpine and Ice sheets The last glacier retreated from New England about 13,000 years ago. It changed the New England landscape greatly. Carved U-Shaped Valleys Left Glacial Erratics, Till, Moraines, Eskers, outwash plains, aretes, tarns, cirques and whalebacks Glaciers play a major role on Earth by maintaining sea levels and providing fresh water for people (5). Human caused global warming likely will have a negative impact on the earth’s glaciers (11) An increase in the Earth’s temperature will decrease Glacial area, and sea levels will rise greatly (11). A decrease in Earth’s temperature increases glacial area and sea levels will drop (11). Figure 4. Parts of an alpine glacier (7) Glacial movement can lead to the formation of Lateral Moraines or leftover debris that forms ridges along the side of the glacier, Medial Moraines, ridges between 2 lateral moraines and Terminal Moraines or ridges of till formed at the end of a glacier (3, Fig. 6). When glaciers erode the landscape they often pick up small and large boulders (glacial erratics, Fig. 7) and move them up to 100’s of miles. Glaciers advance and retreat based on the overall glacial budget. As they advance and retreat they form several different depositional land forms such as: Kettle Lakes formed from melting glacial icebergs (3, Fig. 7) Eskers or areas made of sand and gravel made from glacial streams (3, Fig. 7) Outwash Plains formed from glacier melt water (3, Fig. 7) Till: Material deposited as the glacier melts (3, Fig. 7) Glaciers retreat and/or advance based on the difference between the amount of snow falling within the Zone of Accumulation (head of the glacier, 3, Fig. 5) and the amount of melting at the Zone of Wastage (terminal end of the glacier, 3, Fig. 5) Icebergs formed by Calving often occur here (3, Fig. 5) During the movement of glaciers, crevasses (Cracks created when a glacier moves over irregular terrain, 3, Fig. 5) form in the brittle ice of the uppermost 50 meters of the glacier called the Zone of Fracture (3, Fig. 5) Glaciers erode the landscape through Plucking and Abrasion (3, Fig. 5) Abrasion Zone of Fracture Surprising Facts Figure 2. a. Ice sheet b. Alpine glacier (7). Results Work Cited 1) GlacialGeology.htmlhttp:// 2)Ganopolski A, and Calov, R (2012) Simulation of glacial cycles with an Earth system model. In Climate Change, A Berger et al. (eds.), part 2, 49-55, doi: / _3, Spinger-Verlag, Vienna 3)Tarbuck, Edward J. and Frederick K. Lutgens, Kenneth G. Pinzke and Dennis Tasa (Feb 14, 2008) Applications and Investigations in Earth Science (6th Edition) 4) 5) glaciers.pdfhttp://web.mit.edu/museum/about/pr/2012/vanishing- 6) 7) 8) 9) 10) 11) Figure 3. Formation of glacial Ice (9). Glaciers hold a 75% of the world’s fresh water (5). If the glaciers melted, the world’s sea level would rise by 230 feet (5). Alpine glaciers form high up in the mountains in b owl shaped depressions (Cirques) that create areas of snow accumulation and ice formation (3). The main portion of Alpine glaciers are U-Shape valleys called Valley Troughs (3, Fig. 4). Other glacial features that form high up in mountains include: Hanging Valleys: tributary glaciers located above the main glacier (3, Fig. 4). Arêtes: sharp-edged ridges (3, Fig. 4) Tarn: small alpine lakes formed in cirques (3, Fig. 4). Horn: Peak shaped like a pyramid (3, Fig. 4) Figure 7. Parts of a Depositional Landform (10). Figure 5. Parts of a Glacial Budget (8 ). Figure 6. The different kinds of moraines (9, Fig. 6).