D. Evan Stribling
a larger mass of compacted snow and ice that moves under the force of its own gravity (weight) They erode in some places deposit in others
Areas ALWAYS covered by snow Can form at any latitude as long as elevation is high enough Snow line- lowest elevation at which the layer of permanent snow occurs in summer If an area ever does not have snow it is below the snow line
Begin as firn (a granular ice material similar to a snowball) Firn piles up in layers and ice crystals enlarge Once weight of layers travels under its own weight it is a glacier
1. valley (alpine)- forms in valleys of mountains Smaller, all continents except Australia, Largest ones in Alaska 2. continental Polar regions, thousands of meters thick, Greenland and Antarctica, circular or oval in shape If breaks off and reaches sea is called an iceberg
Glaciers are always moving Friction from bedrock slows glacier- therefore top and middle of glacier move faster (same with streams!)
1. Basal slip- friction between glacier and ground melts ice, reduces friction, allows glacier to move due to gravity Only at base 2. Plastic flow- crystals deform continuously allowing them to slide past one another Crystals end up very long, flat and thin, If glacier reaches a steep slope crevasses (cracks at the surface) form. Observed by placing stakes in glacier.
Removes loose material, which then is used in abrasion Till- unsorted, unstratified material left by a glacier Moraine- deposit of till Lateral moraine- side, medial moraine- 2 glaciers and their moraines meet, terminal moraine- at ice front
Rock Flour- clay and silt beneath glacier from crushing of rock Glacial Milk- melt water with rock flour in it Striations- long parallel scratches Show direction of movement Most post glacial rock is polished smooth *Plucking- glacial ice melts, fills cracks in rock, refreezes and breaks rock, then material is carried off
1. Outwash- material deposited by glacial melt water- sorted and stratified 2. Moraines- deposits of till 3. Drumlins- long, smooth, canoe-shaped hills found in groups Thought to form when a glacier runs over a previous moraine Point in direction of movement
4. Outwash plains- broad flat areas in front of a glacier 5. Eskers- winding ridges of sediment created by deposition of a stream running through a glacier 6. Kames- cone shaped hills of stratified (layered) sand and gravel Form where streams flowing on top of a glacier drop their load at the ice front or in mid glacial lakes
7. Kettles- bowl shaped hallows in moraines and outwash plains Form where a block of ice has been buried 8. Lakes- moraine dammed and kettle lakes
A. where snow is always present A. B. below the snow line B. C. low elevation C. D. can form anywhere D.
A. Inertia A. B. Gravity B. C. Liquid water C. D. Slick ice D.
A. Kame A. B. Esker B. C. Drumlin C. D. Moraine D.
A. Outwash plain A. B. Esker B. C. Kettle C. D. Kames D.
A. Ocean currents A. B. Earth flow B. C. Stream C. D. Mud slide D.
Enviro-Tacklebox: Module 4: Forces in the Environment: Glaciers: Movers and Shapers. Louisiana Public Broadcasting (2002). Retrieved March 26, 2008, from unitedstreaming: Spaulding, N. (2003). Earth Science. Illinois: McDougal Littell Stafford County Public Schools Retrieved March 26, 2008: