Lecture - Oct. 13th and 15th
Lecture - Oct. 13th and 15th 11883 - GEO 105 - 01
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This 7 page Class Notes was uploaded by Andrea on Tuesday October 20, 2015. The Class Notes belongs to 11883 - GEO 105 - 01 at Grand Valley State University taught by Tara Ann Kneeshaw in Fall 2015. Since its upload, it has received 27 views. For similar materials see Living with the Great Lakes in Geology at Grand Valley State University.
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Date Created: 10/20/15
Living with the Great Lakes Notes from class on October 13th and 15th 2015 Mining 0 Coal 0 Michigan has economic deposits of coal 0 Thin seams thin layers that can that be 3 6 inches in width sometimes big enough to reach a foot 0 This makes the coal very hard to mind and economically mining this type of coal outweighs the profit because it takes more work and time I Essentially you have to scrap off the first layer on the Earth s surface and then extract the coal 0 Potentially it could be mined for profit and used as a potential resource in the future economically But not yet 0 However early one we tried to mine coal 0 Late 1800 s Early 1900 s I Last mine closed in 1952 Last time we economically mined coal as well I But at one time 160 coal mines were active I There was no northern or UP mining I Main areas included Bay Saginaw Tuscola and Genesee 0 Problems with mining in the Great Lakes region I The overall quality of the coal is low grade It doesn t hold up well as a solid During transportation it s common for it to turn into dust or powder I Not extensive laterally The seams of coal as spread of sporadically 0 Coal reserves of Michigan are estimated to total 220 million tons of coal Copper 0 Tophat Where do you think copper is exclusively found in the Great Lakes Region I Western UP 0 Copper is an ore mineral Ore minerals form under different types of conditions as opposed to limestone dolomite etc Copper is found exclusively in Western portion of UP Keweenaw Peninsula Copper Country and Copper Range 0 Copper Range dating back to the rift Hot material coming to the surface way back when and heating up the rocks and depositing metal 0 Almost all pure copper metal Native copper Which is rare to find in nature 0 Today Copper mines No one is finding pure copper 0 Looks like sandstone 0 Copper is now found by using chemical analysis 0 More than 20 of copper mining it and finding big chunks elements most contain traces 0 Iron and Copper are the two most economically important materials in Michigan 0 Both Iron and Copper formed during the Precambrian rocks but by two very different mechanisms 0 Copper formed during the rift I Mixed in with conglomerate and basalts associated with the rift I 1 Bringing superheated groundwater and probably acidic and low pH condition it puts any metal ions with that solution Dissolve into water and travel in it I 2 As water cools fills into fissures cracks and gas cavities of the lava with pure copper and silver I 3 Water evaporates and precipitation out and leaves metal ions 0 Types of Copper 0 A soft metal 0 All Michigan is pure metal 0 Float Copper Picked up and moved chunk of copper that was torn from rock by a glacier carried along and deposited somewhere else I Some is found as one mass or in native copper o Amygdaloid almond shaped deposits in rock 0 Holes in the rock where copper filled o Conglomerate rounded pebbles in a finer sedimentary grained matrix rock sometimes with copper also known as pudding stone 0 Unique type of rock associated with copper I Light colored dark pebble rare conglomerate I Lots of copper has been found in pudding stones or matrix in the background I Long term commercial success from amygdaloid o Melted down copper is easy People extract the copper and toss the rock away 0 Most use copper today wiring light bulbs circuits copper pipes 0 Trace amounts in electrical industry 0 Iron o Widespread Far more common globally 0 Michigan has a unique concentration of iron I In 1844 Surveying the land the surveyors were using a compass and weird things were happening with their needles 0 Teal Lake Negaunee Nawganee 0 Empire mine with 28 million tons of more iron ore a year I Iron is used mainly today for steel 0 Iron Ranges UP only middle part I Vermilion Mesabi and Cuyuna ranges in Minnesota 0 And Michigan Minnesota and Wisconsin Most iron deposits in the world I Marquette Menominee Gogebic lron Ranges in Michigan and Wisconsin 0 00000 I Purity and quality is rare How did it form I lron formed during Jurassic to today 200 million years ago I Long slow process 0 Iron formation contains more than 50 of iron 0 A rock is called iron ore pure iron Highly concentrated I lron formation will provide the iron that will be iron ore 0 Moves in water easily similarly to copper 0 Weak acid go into solution 0 Moves and precipitates out depositing iron 0 Can t see from the surface glacial deposits on top 0 Overtime weathering 0 Long time where the iron was exposed during the ice age and water would move iron Michigan s most valuable nonfuel mined commodity Lake Superior in 1994 produced 95 of the US s supply of iron ore Minnesota leads the nation with 70 Michigan produces the rest 25 Ohio has very little percentage Living with the Great Lakes Notes from class on October 18th 2015 Glacial History of the Great Lakes Region Quaternary period Most recent period Ice Age 0 0 Multiple ice ages But warm at times I Pleistocene in the Quaternary era Spanned 26 million to 11200 years ago Holocene last 10000 years We ll get into it later 0 Native people living in the Great Lakes region In the scale of Earth s geological history the Pleistocene is 38 seconds in a 24 hourday During the Quaternary period c 2 million year ago Everything is covered in ice It creeps in as it freezes temperatures lower and melts back as temperature rise 11 800 years ago ice advanced toward Minnesota 10000 ice retreated for the last time Native Americans present in Great Lakes area Glaciers 0 Massive body of ice that moves over land under it s own weight through the action of gravity I Example Water flowing down hill Ice slowly Ice follows similar patterns of water Finds the path of resistance As moving ice grindingcrushing in its path Slow powerfully I Sculpting the landscape Conditions Glacier Formation Cold climate persists snow year round Glaciers start as patches of snow in the mountains that survive the summer and build Sufficient moisture in air to provide precipitation Amount of winter snowfall must exceed summer melting to build glaciers Glaciers start with snow I Snowfall and accumulates o Pressed dense and compacted gt similar to metamorphic and sedimentary rock process I Snow if 90 air 0 Overtime air is reduced and glacial ice has lt20 air Compares and compacted Individual ice crystals interlock to one another solid mass Similar to mineralrock formations Less time than rock formation Few years snow Rocks lots of time 0 Bottom of Glacier 0 Really old 0 Top is the youngest Bottom is the oldest I Bottom Subject to extreme forces because it s subject to weight above and pressureforce from thickest part of glacier very dense Chunks fall off caving I Describe ice in layersstrata like rocks Record of each year of accumulation 0 Ex Sedimentary rocks visible layers Annual cycles ice deposition Advances in winter retreat in summer 0 Dirty line depositing sediments I ex Tree rings counting Dating ice Literally counting annual cycles lines 0 ex Antarctica little bit of melting still can count regardless of old ice sheets Glaciers always moving Rivers of flowing ice 0 Some parts of glacier flows faster than other parts 0 Movement of Glaciers o Flowing plastically ex mantle toothpaste I able to flow be deformed 0 Flow is fastest near the surface and slower at the bottom I Bottom lots of pressure in contact with rough hard rock Has to overcome friction I Top smoother surface to move 0 Addition to gravity Snow and ice also push down in the direction away from its thickest point I ex Canada glacier pushing out toward us 0 Advancing stage 10 seconds of meteryear 0 Types of Glaciers o Broad categories I AlpineGlaciers mountains or valley glaciers smaller start as snow patches most common 70200000 today High elevations climate steady year round I Continental Glaciers Ice sheets ice caps Huge massive frozen Can cover continents gt 1 km thick Started out as small snow patches 0 Less in the world but more ice in volume 0 Two principal ones I Greenland and Antarctica ice sheets 0 Moving Glacial Ice 0 O Pushing and moving downhill Scraping the surface of the Earth as flowing I bottom catches it and front of the ice Considered a soft element I Can cause no damage to rock break grind etc Ablation retreat of the ice Melting backwards and deposition of sediment till and sediment deposited by a glacier I Meltwater sorts the sediments What was happening during the last Ice Age I Glaciation in Earth s history is a rare thing 0 More common for Earth to be warm very warm I Evidence of widespread glaciation during Pleistocene epoch o Extent 2 million years ago 10000 years ago Laurentide Ice Sheet massive sheet of ice KNOW I Covered North America I Created our Great Lakes I Can still touch it today in Greenland o Melting today but could still advance 0 Ice Age 0 O A time on Earth when it had extensive continental glaciers I Many cycles of glacial periods I lnterglacials Warm period in between Ice Age Causes Variations in sunlight intensity blocking sunlight volcano ash blocks sunlight and is shown on Earth because ash has been settled and buried tectonic plate locations variation in the tilt of Earth s axis angle refraction of light Erosion and deposition of material over large parts of the continents modification of river system creation of million of lakes changes in sea level goes down during formation lsostatic adjustment of the crust Abnormal winds winds are controlled by temperature 0 seasonally weather patterns affected 0 Great Lakes Region Specifically O 0 Focus on 15000 9500 years ago I Period called Wisconsin Glacial Age 0 Responsible for what s at the surface of the Earth today Names to ice lobes I Massive part I Pieces that extend out of the ice finger like lobe I Different lobe sculpt different parts of the landscape 0 SupenorLobe 0 Michigan Lobe o Saginaw Lobe created Saginaw Bay 0 Huron Lobe 0 Erie Lobe I Farthest it got was edge of Indiana south I 2nd farthest was middle of Indiana I The last time is ended at the Michigan border 0 Ice Ages I GreenlandAntarctic glacier ice is still present today I Holocene epoch live in interglacial stage I Very likely that the Earth will experience another glacial advance Perhaps next 10000 20000 years I Ice Age not exactly over I Climate Change what s been normal 0 Climate change is normal I What s not normal 0 Changing fasterthan before Human effect on that o More C02 warmer temperature in average Earth temperatures 0 Greenhouse gases Carbon bound releases C02 I Accumulates I Blocks sunlight 0 Measure of CO2 in ice Preserves record Correlates to temperature I Highest levels are recorded in 125000 years ago during major interglacial periods and at present
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