Geology 102 Notes November 9th-13th
Geology 102 Notes November 9th-13th Geo 102
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This 0 page Class Notes was uploaded by Taylor sandeno on Monday November 16, 2015. The Class Notes belongs to Geo 102 at Illinois State University taught by Bill Shields in Fall 2015. Since its upload, it has received 25 views. For similar materials see Principles of Geology in Geology at Illinois State University.
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Date Created: 11/16/15
Geology 102 Notes November 9 11 and 13th Geology 119 mountain glaciers ow down hill from places of high elevation Glaciers a thick ice mass that originates on land from the accumulation compaction and recrystallization of snow Formation of glacial ice from snow A snow ake is a mineral made of H20 The temperature and rate at which it forms and more things can make all of the snow akes their own unique shapes Over about two months snow akes recrystallize into balls of fern Two types of glaciers Continental Glacier large scale cover 10 of Earth s land 2 largest of the continental glaciers Greenland 17 million km2 Antartica 139 million km2 Mountain Glacier Valley or Alpine Glaciers Smaller than ice sheets lengths greater than widths long and narrow Forms at high elevations and goes down hill Glacier movement150m to add pressure to ow Plastic Flow owing solid 200myr Basil Slip movement Glacier moves on average about 400 meters per year Glaciers move by sliding along the bottom Rotation of grains melting and freezing internal slipping These three processes account for half of the motion Why glaciers form at high elevations lt s colder up higher Zone of ablation general term for loss of ice or snow from a glacier Melting Calving icebergs If it calves in water then it becomes an iceberg Zone of accumulation snow accumulates Terminal moraine the farthest a glacier has moved forward Moraine a pile of unsorted material deposited by ice Ice is added by snow fall in the zone of accumulation and moved away by the zone of ablation 1111 Mountain Glaciers tend to accentuate the landscape ows down hills Landforms particle to these cirque where snow accumulates Ridge where two cirques meet Horn where two or more cirques meet Glacial sediments are underneath the ice lce has a mixture of different sizes of materials in it Spur Turn Tarn Lakes these are located on cirques Zone of accumulation at top of mountain ice fall is the part that moves down the mountain Compresses and expands then at the bottom zone of abulation melting and calving Streams don t ow through a mountain glaciers ows around it Eret The ridge between two cirques Drift All material deposited by a glacier Two Types Till unsorted debris transported by glaciers and deposited on land Sorted Sediments Transported by melted water and transported in Eskers Material is transported through the ice Sometimes just as much snow at the top is added at the bottom and that makes a moraine Moraine piles of unsorted material that has been transported Erratic transported by glaciers out of the northern part of the US The ice age effected the landscape of Illinois Continental Glaciers tend to subdue the landscape ice covers 10 of the Earth s land If you can get ice to last it will accumulate and if it gets thick enough then it will start to ow with gravity Once you get 50m of ice it will start owing This type of glacier is more rounded and very thick in the middle Eskers formed by running water underneath the glacier Landforms associated with continental glaciers drumlins eskers kettle lakes For continental glaciers to form they have to have landmasses by the poles because that is where it is cold enough to keep ice throughout the summer Nebraskan owed into Illinois and then melted and was gone for 200000 years 100000 years after that it came back for 200000 years and then climates changed and it was gone for 200000 years Then climates changed it it came back and then melted again And that kept happening There are three to know Prelllinioan Wisconsinan Glaction The Ice Age Began 18 million years ago and may have ended 10000 years ago Phanerozoic EON Cenozoic ERA Quaternary PERIOD Pleistocene EPOCH ice ago Glacial Deposits as long as there is ice it is owing If it is moving forward then more is being added in the zone of accumulation then lost 1113 ProGlacial Lakes Sediments are sorted in these Lakes form associated with continental lakes Kettle Lakes These are formed when glaciers calve off ice Eventually ll in with sediment and silt Barrow Pits Little lakes next to the interstates Farmer s sell dirt to get a lake but then that part of the farm can t be used anymore Sediments are built up in the outwash plains Esker a river shaped deposit Sits above the ground Deposited by running water so it is sorted They were exploited as natural resources Drumlins Deposited by ice above the land Teardrop shaped contour lines You can tell which direction the ice came from They can occur in pairs or in groups of as many as 100 Only associated with continental glaciers important to know The ice can change the ow of rivers The glaciers changed the ow of rivers in Illinois The biggest glacial lake was Lake Chicago About 13000 years ago all the moraines broke in a big storm All the water headed towards the West towards more moraines It ended up changing direction and going South Was this change unique in time Why did the climate change At one time lllinois was South of the equator Cycles of cooling and warming have changed through history We are currently in an ice age or it may be over We need land masses near the poles to have ice ages Why did the climate change Changing continental positions uplift of continental blocks reduction of C02 in the atmosphere changes in the Earth s orbit Changes in the Earth s Orbit The Milankovitch Theory The more ice there is the cooler it will get The cooler it gets the more ice there will be Eccentricity of the orbit Sometimes the earth s orbit is circular and sometimes its elliptical lf Summer occurs when Earth is farther away from the sun then the summer won t be as warm and some ice will still be able to grow Changes in the Earth s tilt The reason we have seasons When it stands up a little straighter during Summer it will be a little colder If it is more tilted then Summer will be warmer The Precession of the Equinoxes In 13000 years from now Summer will occur in December One day Christmas will be in the middle of Summer Cycles of Global Warming Temperature climates are always changing When geologists think of climate change They think of 100 s of years back not just short changes A volcano can erupt and change the temperature for a long time after that