Lecture - Nov. 10th and 12th
Lecture - Nov. 10th and 12th 11883 - GEO 105 - 01
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This 4 page Class Notes was uploaded by Andrea on Friday November 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 15 views. For similar materials see Living with the Great Lakes in Geology at Grand Valley State University.
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Date Created: 11/20/15
Living with the Great Lakes Notes from class on November 10th and 12th Nov 10th Dunes 0 Lake Michigan has the largest concentration of freshwater dunes in the world 0 30004000 years old Fairly young geologically 0 Created by three actions I 1 Waves deliver the sand I 2 Wind also delivers as well as sculpts the sand formations I 3 Vegetation holds in place the sand with it s roots 0 Example dune grass 0 Sand dunes are incredibly migratory they can move drastically over a 24 hour period 0 Rivers carry glacial sediments from the interior to the lake shore where it s transported up and down the lake by littoral transport I Ex Poop from animals inland will travel to the river after a storm watershed empty into the lake and the lake will dump it right back on the beaches So never go swimmingto the beach after a storm I Ex Pollution Also after a storm you will see lots of trash and sticks big pieces of debris all along the beaches Same situation with poop o The Grand River pumped large particles of sand from all over the state 0 Sand Dunes 0 Sand piled on a beach I Some sort of obstruction lays on the beach plenty following the ice age 0 Wind blows past the obstacle and begins to pile up and around the edges of the obstacle could be a large rock for example 0 Pattern of wind on the rock eventually creates a sand encasing around the rock and the sand continues to build 0 It is essentially flowing over the rock which is why they can migrate easily 0 Over tens of thousands of year the result is our dunes 0 Sand 0 Composition of Lake Michigan sand I 8090 is quartz glass Hard mineral Less tough than diamond but only by a little 1020 feldspar Pink colored stone in granite I 12 magnetite iron and other minerals 0 Rare fulgurites sand that has been struck by lightning I Tan color of sand is from quartz and other minerals getting stained from iron oxide a small rust coating 0 Why does sand squeak Happens when there is a certain amount of moisture in the sand o It is the pressure of your hand foot whatever on the moist grains that makes the squeak 0 Different kinds of Dunes o Parabolic Dunes I Classic Ushaped parabola shape Most common near us Found in areas where extensive vegetation covers stabilizes the dunes o Preserves the dunes c As they form they form by the lakeshore but more backwards and more inland Formation 0 Wind direction creates gentlesweeping slopes as well as slip face 0 Slip face where the sand reaches a peak and then slides down over the edge 0 Form in many systems that overlap 0 Ex North Grand Haven parabolic dunes Blowout Dune Formations Forms when a patch protective vegetation is lost allowing strong winds to blow out sand and form depressions Generally small but can expand o Bowllike o Perched Dunes Literally piles of sand perches on a hillside or cliffs Formation 0 Form when wind travels up a coastal bluff or cliff and removes fine material from the slope along the way 0 Creates really tall sand dunes because they already begin to form so high up 0 Happens on end moraines that come near the lakeshore 0 Ex Sleeping Bear Dunes mostly all perched 0 Linear Dunes Form parallel to shoreline Result of how the lake levels were Temporary 0 Transverse Dunes Elongated dunes Show direction of wind Don t form in a straight line Individual ridges Right angles Little vegetation Temporary and easily disturbed Nov Soil 12th SandDunes Roughly 465 million tons of sand were mined between 19781998 So why do we mine sand 0 Very uniform 0 Same size 0 Chemical purity high concentration of quartz and some iron 0 Piled up in massive accumulations Demand is increasing because of an increase in the number of products that use sand 0 Up for debate whether we should sell more of dunes and extract them 0 Economics vs preservations Uses for sand 0 Foundry sand I Foundries are used to make molds casts of metal parts for automotive industries I High heat resistance because of the quartz rich sand 0 Ex Blown glass doesn t catch on fire when blown because of the quartz 0 Making glass 0 Railroads use sand to increase traction and sand is less coercive than salt 0 Sandblasting use to blast off rust o Furnaces lined with sand 0 Filters Sand naturally filters out bacteria Groundwater wells 0 Fiberglass 0 Oil industry uses high pressured sand to push oil out of the ground Dirt 0 Soil is the accumulation of rock and mineral fragments Must be capable of supporting life I Complex 0 Needs moisture air pockets bacteria and organic material 0 Process I Mechanical weathering physical weathering o Breaks up rocks 0 No change in compositions 0 Ex Freeze and thaw I Chemical weathering 0 Reactions with water or gases in the air 0 Ex Calcite dissolving in slightly acidic water limestone alkalinity I Biological weathering 0 Can be physically or chemically 0 Tree roots physically breaking through the rocks 0 Moss growing on soil acidic chemically 0 Chemical and Physical Properties of Soil 0 Controls Composition I Extent and balancing of weathering climate etc I Composition of material from which it formed 0 Controls Physically I Mineralogy difference of ingredients I Texture feel coarse fine grain particles How well sorted Shape angular or rounded etc Important to how things grow I Organic matter present A little not enough to grow Too much too rich 0 Great Lakes Soil 0 Soils have weird names Alfisols entisols histosols 0 Significant difference between Lower Peninsula LP and Upper Peninsula UP 0 Last retreat of ice I The action of the ice left the sediments and overtime wind plants water animals and people changed the soil 0 Different soil types have different characterizations 0 Different Soil Characterizations o Layers horizons Many horizons can vary from size but depends on natural setting I Depth can vary of each horizon 0 Organic soil O is the top layer twigs leaves bugs 0 Soil Horizons O Organic A Horizon beneath O Mixture of organic matter and rock and minerals Usually where the roots go o E Horizon Bleached out Lighter color than other layers Zone of leaching Things get sucked out of it and carried downward o B Horizon Zone of Accumulation Accumulation of iron aluminum and clay leached from Zone E Contains soluble minerals C Horizon Weathered Parent material Bedrock Horizon