Final Exam 3 GY102 I Introduction to Glaciers A Glaciers 1 River of ice 2 Alpine glaciaton Currently located in major Mountain Ranges and Polar Regions 3 Contnental glaciations Glaciers have occupied bigger sections of North America B Continental Glaciations in North America Pleistocene Glacial stages Wisconsin 30000 8000 Holocene intragracial 8000 today o 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 melting What causes changes in glacial cycles Changes in global climate Western US Extensive alpine glaciations o Ex The Rocky Mountains Cascade Pluvial Lakes lakes that over flow from rainfall resulting from wetter climate conditions Channeled 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 age Mid Western U S 1 Moraines 2 Drumlin Fields 3 Glacial tilt has soil built up 4 Swamps lots of wetness poor surface drainage Ice sheet expanded from the origin Northwestern U S 1 Hudson Bay Canada 2 Great Lakes 3 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 striations 5 Glacial Polish II Causes of Climate Change A Long term climate changes 1 Changes in Earth s eccentricity Controls max and min distance from Sun Naturally changes on 100 000 year cycle 2 Earth s Obliquity Changes in angle of tilt Increased tilt increased seasonality of temp Naturally changes on tens of thousands of years cycle 3 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 Sun 1 Sun goes through natural cycles of increasing and decreasing strength a Tens of thousands of years long 2 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 Europe The 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 circulation A Human Activities 1 Fossil Fuel Combustion Increases Co2 Ch4 concentrations in atmosphere Traps LW radiation in lower atmosphere causes surface tempts to rise 2 Deforestation Tree stores Co2 die to photosynthesis Tree removal increases Co2 in atmosphere I Introduction to Glaciers A Formation 1 Climate Conditions 2 Firn B 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 Processes A Glacial Movement 1 Gravity 2 Basal slip B Mass Balance Alpine Glaciers 1 Zone of Accumulation 2 Zone of Ablation 3 Equilibrium Line Firn Line 4 Glacial advance 5 Glacial Retreat Produces striations polish C Eroisional Landforms 1 U shaped valley are frequently present Fjords Glacial Processes Landforms A Glacial plucking Melting refreezing cracks B Glacial Abrasion scraping of bedrock by rocks transported in ice Hanging Valley Small tributary glacier valley joins larger valley waterfalls 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 Ar te ah rate knife shaped ridge formed by glaciers on 2 sides 4 Horn 3 sided peak shaped by glaciers on all sides II Depositional Processes and Landforms A Depositional Process 1 Abrasion 2 Melting at shout 3 Glacial sediment Glacial till type of deposit that has wide array of sizes glacial flour decrease in velocity is glacial a Result all sediment will sort together with a huge variety of particle size b Glacial flour fine sediment that is transported by rivers i 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 boulders B Moraines 1 Linear hills or mounds a Located on the edges of glacier b Reason that s where melting occurs lots of friction with ice material and bedrock 2 Types a Terminal Moraine i Right on southern most edge of the glacier ii Short melting iii Furthers iv Perpendicular to glacier moraine makes a T shape b Recessional Moraine i A series of terminal moraines ii Half in a glacial retreat shrink the melting process iii Each time the melting stops a new terminal moraine will form c Lateral Moraine i Melting due to frictional curve in the valley ii Moves along side the glaciers of terminal and bedrock moraine C Landforms d Medial Moraine i Joining of two lateral moraine of two glaciers that are merging ii Middle of the glacier e Outwash Plain deposition landforms form from deposits drained out from the melt water into ice sheets f 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 erosion i Glacial plucking more steep more erosion Ice sheet goes over ridge by glacial plucking ii forming this hill mound e Erratic large boulders transported back distances from point of origins Ablation The removal of snow and ice by melting or evaporation typically from a glacier or iceberg Drumlin a low oval mound or small hill