Geog 1113 Notes- Week 4 (Mon)
Geog 1113 Notes- Week 4 (Mon) GEOG 1113
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This 3 page Class Notes was uploaded by Victoria Koehl on Tuesday September 13, 2016. The Class Notes belongs to GEOG 1113 at Georgia State University taught by Larry Kleitches in Fall 2016. Since its upload, it has received 30 views.
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Date Created: 09/13/16
Geog 1113 Notes Braking Up is Hard to Do Part 1 Weathering The breakdown of rocks into smaller pieces (sediments) Erosion The process where small pieces of sediments are transported by running water, wind, gravity, glaciers, and man Deposition The process in which these sediments are dropped off at another location There are two primary types of weathering Physical weathering is the breakdown of rocks and minerals into smaller pieces without a change in chemical composition Root/Plant wedging action, Ice/Frost wedging action, Exfoliation (layers peel off), and Abrasion (scraping off) Chemical weathering is the breakdown of rocks and minerals into smaller pieces by chemical action; rocks break down as it changes chemical composition Oxidation Oxygen combines with elements in rock and reacts, rusts Hydration Water can dissolve away many earth materials Carbonation Carbon dioxide dissolves in water to form carbonic acid which makes acid rain that chemically weathers rocks Four factors that affect the rate of weathering: Surface Area Exposing more surface area will increase the rate of weathering Particle Size Larger particles weather slower while smaller particles weather at a faster rate Chemical Composition Certain rocks and minerals are naturally weaker than others while others are more resistant Climate Warmer, moister climates have the most weathering; heat and water speed up all chemical reactions, this is the most important factor in weathering Soil forms from the weathering of the rock below it, the solid rock is called the bedrock Soil has different layers called Soil Horizons OHorizon is the very thin surface covering AHorizon (Topsoil) is the dark surface soil that contains a lot of living material and dead plant/animal remains (humus), this layer has the nutrients needed for plants BHorizon (Subsoil) is the lighter colored soil with less nutrients and more clay CHorizon (Regolith) is the larger rock fragments that sit on top of the unweathered bedrock Transported soils Type of soil that is formed in one place and transported present location by glaciers Residual soils Type of soil that is located above the rocks it formed from Principle agents of erosion: Running water, glaciers, wind, gravity, and man Four basic products of weathering: Soils, solid sediments, colloids/clay particles, and ions Running water Sediments that have been transported through running water appear rounded and smooth and are deposited in sorted piles Glaciers Sediments that have been transported by glaciers appear scratched, grooved, and deposited in completely unsorted piles Wind Sediments transported by wind appear pitted (random holes) and frosted (glazed look), and are deposited in sorted piles Gravity Sediments transported by gravity are found in piles at the bottom of cliffs or steep slopes, they appear angular and unsorted Running water can transport sediment in three ways: Solution The smallest particles of weathering are dissolved in the water and they are transported in a solution Suspension Clay sized/colloids are carried along with the water molecules during erosion, neither at the top nor the bottom but in the middle of the running water Saltation Solid sediments are rolled and bounces along the bottom of a river/stream because they are more dense Sediments being transported by a river/stream travel slower than the water due to friction Stream/river bed The bottom of a stream or river Bed load The material being transported along the bottom of a river/stream Downcutting When weathering and erosion, along with running water, cause the stream/river to become wider and deeper over time Factors that influence erosional rates in running water and glacial ice: Slope of the land as this increases the water velocity increases, particle size the water can carry also increases, therefore the amount of erosion increases Volume as the size of the water/glacier increases their velocities increase, the particle size they can carry also increases, therefore the amount of erosion increases Position within the running water Water is traveling faster around the outside of turns which so there is more erosion there, water travels slower on the inside of turns so deposition occurs on the inside In a straight flowing river/stream, sediments travel the fastest in the center directly below the surface Five primary ways man can cause erosion: Forestry vegetation removed, no roots= soil erosion Strip mining removing rock cover for resources below, loose sediments erode away Construction clearing land to build buildings, cause loose soil to erode away Improper farming not plowing land at right angles to slopes causes soil erosion Salting highways the salt is washed off the road, preventing plant growth along the sides Most deposition occurs in standing bodies of water Deposition is caused by the slowing down of the agent of erosion Three factors influence the rate of deposition: Sediment size, shape, and density Graded bedding/ Vertical sorting A situation where larger particles settle on the bottom and smaller particles settle at the top; occurs naturally when fast moving water meets a large standing body of water 2 Horizontal sorting A situation where slowly moving water enters a larger still body of water, causing larger particles to be deposited closer to the shoreline Crossbedding: A situation where layers of sediments are deposited at angles to one another as a result of a change of direction of the erosional agent (sand dunes, deltas, alluvial fans) Delta A fan shaped deposit that forms at the mouth of a stream when it enters a larger body of water, particles are horizontally sorted Alluvial fan A fan shaped deposit of sediments that forms when a stream flows out of a mountain on to flat, dry plains, not under water, this only happens on the land 3