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Final Exam 3: GY102I. Introduction to GlaciersA. Glaciers 1. River of ice2. Alpine glaciaton: Currently located in major Mountain Ranges and Polar Regions3.Contnental glaciations: Glaciers have occupied bigger sections of North AmericaB. Continental Glaciations in North America Pleistocene- Glacial stages- Wisconsin- (30000-8000)- Holocene intragracial-8000 todayo Alpine glaciers and ice sheets melting - Cordilleran ice sheet (small)- Lauren tide- ice sheet (large)- Lobes (“landlord of ice sheets”)- finger like extensions of ice sheet that stick out from the glacier)o Helps prevents meltingWhat causes changes in glacial cycles? - Changes in global climateWestern US- Extensive alpine glaciationso Ex. (The Rocky Mountains, Cascade) - Pluvial Lakes- lakes that over flow from rainfall resulting from wetter climate conditionsChanneled Scablands-Missoula Floods: refer to the catastrophic floods that swept periodically across eastern Washington and down the Columbia River Gorge at the end of the last ice ageMid-Western U.S.1. Moraines2. Drumlin Fields3. Glacial tilt=has soil built up4. Swamps- (lots of wetness & poor surface drainage)Northwestern U.S.- Ice sheet expanded from the origin1. Hudson Bay- Canada2. Great Lakes3. Isostatic Rebound- N.E United States pulls weighted ice sheet as it pushes crust deeper into the earth, when melted weight is released causing surface to rise in elevation. 4. Grooves, striations5. “Glacial Polish” ‘II. Causes of Climate Change:A. Long term climate changes1. Changes in Earth’s eccentricity • Controls max and min distance from Sun• Naturally changes on 100,000-year cycle2. Earth’s Obliquity- Changes in angle of tilt- Increased tilt=increased seasonality of temp - Naturally changes on tens of thousands of years cycle3. Changes in distribution of land & ocean- Plate tectonics Cause:  Continents move  Ocean basins form & widen Mt. Ranges form & erode Tens of millions of years 4. Strength of the Sun1. Sun goes through natural cycles of increasing and decreasing strength a. Tens of thousands of years long2. Sunspots follow an 11-year cycle (affects incoming radiation)3. More output from the sunwarmer Earth. B. Quicker Changes 1. Changes in atmospheric gas concentrations & particulate matter - Volcanic Eruptions * Add sulfur dioxide and particulates (aerosols) to stratosphere * Increases atmospheric reflectivity * Causes global cooling for 1-2 years Year Without a summer 1816 -Eruption of Mt. Tambora (Indonesia) in 1815- Caused global cooling and wetness-New England had snow in June -Massive crop failures in EuropeThe Little Ice Age (Maunder Minimum) 1250-1800 - Colder climate in N. Hemisphere1-1.5 degrees C) esp. Europe- Thames River froze- Warm summer stopped- Severe winters- Caused famine and disease across N. hemisphere- Believed to have been caused increased volcanic activity decreased solar output and changes in ocean circulationA. Human Activities1. Fossil Fuel Combustion- Increases Co2 & Ch4 concentrations in atmosphere - Traps LW radiation in lower atmosphere causes surface tempts to rise2. Deforestation- Tree stores Co2 die to photosynthesis- Tree removal increases Co2 in atmosphere I. Introduction to GlaciersA. Formation 1. Climate Conditions 2. FirnB. Types of Glaciers - Alpine- Mountain ranges- Continental- Massive ice over large land area- Ice sheet (Antarctica, Greenland)- Ice cap (Iceland)- Ice field (Patagonia)Valley- an ice mass constricted within a valley that was originally formed by stream action II. Glacial ProcessesA. Glacial Movement1. Gravity2. Basal slip B. Mass Balance (Alpine Glaciers)1. Zone of Accumulation2. Zone of Ablation3. Equilibrium Line (Firn Line)4. Glacial advance5. Glacial RetreatGlacial Processes & LandformsA. Glacial plucking- Melting, refreezing, cracksB. Glacial Abrasion- scraping of bedrock by rocks transported in ice- Produces: striations & polish C. Eroisional Landforms 1. U-shaped valley- Hanging Valley: Small tributary glacier valley joins larger valley waterfalls are frequently present- Fjords-*Even smooth rounding shape, higher elevation u-shaped valleys, and have been flooded.2. Cirque: bowl shaped depression at the head of a glacial valley (tear drop shape)* A lake inside a cirque is formed in part by glacial melting* - Tarn- (a small mountain lake) 3. Arête (ah-rate): knife shaped ridge formed by glaciers on 2 sides 4. Horn- 3 sided peak shaped by glaciers on all sidesII. Depositional Processes and LandformsA. Depositional Process1. Abrasion2. Melting at shout3. Glacial sedimentGlacial till (type of deposit that has wide array of sizes) & glacial flour decrease in velocity is glaciala. Result= all sediment will sort together with a huge variety of particle size.b. Glacial flour= fine sediment that is transported by riversi. Result= sediment that gets trapped inside the glacial ice, particles come from polarizing in the glacial ice resulting into flour- Glaciers carry huge amounts of sediment as it moves transporting soil, rocks, and some med size bouldersB. Moraines1. Linear hills or moundsa. Located on the edges of glacierb. Reason: that’s where melting occurs, lots of friction with ice/material, and bedrock)2. Typesa. Terminal Morainei. Right on southern most edge of the glacierii. Short (melting)iii. Furthers iv. Perpendicular to glacier (moraine makes a “T” shape)b. Recessional Morainei. A series of terminal morainesii. Half in a glacial retreat (shrink the melting process) iii. * Each time the melting stops, a new terminalmoraine will form*c. Lateral Morainei. Melting due to frictional curve in the valley and bedrockii. Moves along side the glaciers of terminal morained. Medial Moraine i. Joining of two lateral moraine of two glaciers that are mergingii. Middle of the glacierC. Landformse. Outwash Plain- deposition landforms form from deposits drained out from the melt water into ice sheetsf. Continental ice sheets forms head of ice sheets with melt water streams that form from the ice sheet edges have a lot of melt water causing sediment.g. Finger lakes- large lakes created with river valleys that are eroded by ice sheets (Ex. Great Lakes)h. Drumlin-hill or mound made from glacial tilt (2 symmetric)i. Esker- forms underneath the melt sheet enlighten ridges of sediment deposited by rivers underneath the ice sheet. j. Rouche Mountonee- hill/mound formed by glacial


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UA GY 102 - Final Exam 3

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