1 Glaciers Prentice Hall Chapter 8, Section 4 By Rusty Sturken December, Duluth Middle School Sixth Grade Earth Science

2 Glaciers A glacier is any large mass of ice that moves slowly over land. A glacier is any large mass of ice that moves slowly over land. *Glaciers only form in areas where more snow falls than melts *Snow builds up year after year *Pressure on the snow at the bottom turns it into ice *Gravity pulls the glacier downhill

3 Glaciers A valley glacier is a long, narrow glacier that forms high in a mountain valley * flows a few centimeters to a few meters per day A valley glacier is a long, narrow glacier that forms high in a mountain valley * flows a few centimeters to a few meters per day A continental glacier is a glacier that covers much of a continent or large island A continental glacier is a glacier that covers much of a continent or large island *much larger than valley glaciers *spreads out like pancake batter * cover Antarctica and Greenland

4 Glaciers Glaciers Valley glacier Continental glacier pubs.usgs.gov/of/2004/1216/images/mendenhall.gif

5 Continental Glaciers Continental glaciers cover about 10% of Earth’s surface The glacier covering Antarctica is over 14 million square kilometers and 2 kilometers thick An Ice Age is a time when continental glaciers cover large parts of Earth’s surface * The last ice age ended 10,000 years ago. * Ice has covered 1/3 of Earth

6 Glacial Erosion The two processes by which glaciers erode the land are plucking and abrasion The two processes by which glaciers erode the land are plucking and abrasion Plucking is the process when glaciers pick up rocks as they flow over the land, the rock freezes to the bottom of the glacier Plucking is the process when glaciers pick up rocks as they flow over the land, the rock freezes to the bottom of the glacier Abrasion is the grinding away of rock by other rock particles carried in water, ice, or wind. Rocks frozen to the bottom of a glacier scrape across rocks on the Earth’s surface. Abrasion is the grinding away of rock by other rock particles carried in water, ice, or wind. Rocks frozen to the bottom of a glacier scrape across rocks on the Earth’s surface.

7 Glacial Deposition When a glacier melts, it deposits the sediment it eroded from the land, creating various landforms. When a glacier melts, it deposits the sediment it eroded from the land, creating various landforms. Till is the mixture of sediments that a glacier deposits directly on the surface of the Earth. Till is the mixture of sediments that a glacier deposits directly on the surface of the Earth. A moraine is a ridge of till deposited at the edge of a glacier. A moraine is a ridge of till deposited at the edge of a glacier. A terminal moraine is the ridge of till at the farthest point reached by a glacier. A terminal moraine is the ridge of till at the farthest point reached by a glacier.

8 Great website

9 Moraines Terminal moraines and end moraines are the same thing

10 Long Island, N.Y. is a terminal moraine from the last ice age

11 Glaciers

12 Formations from glaciers Moraines Moraines Cirques(bowls) Cirques(bowls) Arêtes Arêtes Horns Horns Fiords Fiords U-shaped valleys U-shaped valleys Glacial lakes Glacial lakes Kettle lakes Kettle lakes Background photo from: Teton Glacier in Grand Teton National Park, Wyoming

13 See Page 272 Prentice Hall Science Explorer, Earth Science 2002, 2001 Pearson Education, Inc.

14 See Page 273 Prentice Hall Science Explorer, Earth Science 2002, 2001 Pearson Education, Inc.

15 Cirque A bowl-shaped hollow eroded by a glacier Logan Mountains, Northwest Territories, Canada

16 Arête A sharp ridge separating two cirques (bowl- shaped hollows) A sharp ridge separating two cirques (bowl- shaped hollows) z.about.com/d/geology/1/0/K/K/arete.jpg

17 Horn Sharpened peak formed when glaciers carve away the sides of a mountain. Sharpened peak formed when glaciers carve away the sides of a mountain. Glacier N.P.

18 Fiord Form when sea level rises, filling a glacier-cut valley Form when sea level rises, filling a glacier-cut valley

19 Kettle Forms when depression in till fills with water Forms when depression in till fills with water

20 Fiord/ U-shaped valley

21 Glacial Lakes Form in long basins created by plucking and abrasion Form in long basins created by plucking and abrasion Excellent website Great LakesFinger Lakes in New York gerLakes_ISS010E09366_lrg.jpghttp://earthobservatory.nasa.gov/Newsroom/NewImages/Images/Fin gerLakes_ISS010E09366_lrg.jpg Also excellent website

22 THANK YOU to all of my Sixth Grade students who helped me improve my Powerpoints You helped me with: oPoPoPoPictures for backgrounds oBoBoBoBetter font oAoAoAoAnimation oFoFoFoFiguring out what works or doesn’t oIoIoIoI still have a long way to go