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Ice, Wind, and Wasting “By the breath of God ice is given, And the broad waters are frozen.”Job 37:10 glacier – thick ice sheet that slowly moves under its own weight continental – sheets that cover huge areas of relatively flat land (Antarctica, Greenland) valley/alpine – smaller, highland glaciers crevasse – deep crack/fissure in glacier cirque – bowl shaped depression formed by a glacier in the valley where it begins horn – three or more cirques cut into a mountain peak (Matterhorn) striae – deep grooves and scratches in bedrock in the direction of the glacier's movement till – broken rock carried by a glacier moraine – heap/ridge of till left by a retreating glacier drumlin – formed when an advancing glacier overruns its old moraines outwash – sand, gravel, other sediments washed out from beneath a glacier by water from melting ice Ice Age – period of history during which much of earth's high latitudes were apparently covered with glaciers; glaciers and cold weather did not cover the entire earth during the Ice Age; only present deflation – removal of loose particles of sand and soil by wind; blowout – shallow or hollow depression in ground scooped out by deflation desert pavement occurs when wind blows away most loose surface materials over the years, leaving only pebbles, rocks, and boulders too heavy for wind to move sandstorm – strong windstorm in an arid region that produces thick clouds of blowing silt loess – deposits of clay and silt left by a sandstorm sand dunes – huge heaps of loose, windblown sand common in deserts and near beaches; crescent, parabolic, transverse [p.263] abrasion – sandblasting action of windblown sand mass wasting – general term for movements of rock and soil caused by gravity; soil creep most common – very slow downslope movement of soil and rock fragments mudflow – rapid downhill movement of loose, water-saturated soil landslide – sudden slide of rock or soil down a slope avalanche – landslide involving snow or ice rockslide – landslide consisting primarily of bedrock rockfall – not a landslide; piece of rock breaking off rocks from a cliff how to prevent erosion – planting trees/ grass/vegetation; planning drainage; terracing Activity 1. Have each pair take a handful of play dough and smooth it out like a pancake. Ask one student from each pair to take a model glacier ice cube and drag it (rough end down) slowly, one way across the play dough while pushing down with medium pressure. (Pairs may do this twice so each student has the chance to participate.) 2. Have each pair of students look closely at their model glaciers and playdough landscapes and discuss the following questions together: a. What kind of marks does the glacier make in the play dough? b. Does the glacier leave anything behind (dirt, rocks)? c. Are there interesting features on the surface of the glacier like crevasses? d. How is the dirt and gravel distributed throughout (randomly)? e. How was the play dough “landscape” affected by the sediment in the “glacier” (scratches, grooves, large boulders picked up and then deposited by glaciers)? 5. Now, have each pair of students put their model glacier into a pan and observe it melting. (This is more similar to a continental glacier, while the scraping activity represented an alpine (valley) glacier.) Have each pair of students look closely at their model glaciers and discuss the following questions together: a. What do you notice about how the rocks and dirt are distributed by the melting ice (sediment is unsorted, piles are of mixed sizes)? b. Describe the areas and the clues the glaciers left behind. Homework Section Review 10.2 (p. 265) Investigative Plan