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72 terms

Weather, Erosion, and Deposition

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Weathering
Physical and chemical breakdown of rocks at or near the surface
Physical weathering
The mechanical breakdown of rock into smaller pieces without a change in the mineral's composition
Frost Action
Water freezes in a crack of rock surface, expanding and splitting the rock. Alternate freezing and thawing form pot holes and frost heave.
Plants and animals
Plant roots force their way into cracks, and ____ expose rocks to the surface by digging.
Exfoliation Dome
Layers of rock peel off the main body of the rock
Temperature Change
Alternating hot and cold weakens the rock as it expands and contracts
Abrasion
Pieces of rock collide with each other due to transportation by wind, ice, water, and gravity
Chemical weathering
The process by which chemicals breakdown rock through a change in its composition. Happens fastest in hot and moist climates
Oxidation
Occurs when oxygen from the air combines with iron-rich minerals of the rock. (Rust)
Carbonation
Occurs when water combines with carbon dioxide in the air to form carbonic acid.
Carbonic Acid
Easily dissolves limestone and marble
Hydrololysis
Water combines with minerals such as mica and feldspar found in granite, to form clay, the rock weakens and crumbles apart.
Exposure
Rate and type of weathering are dependent on exposure to air, water, and living things.
Particle size
An increase in surface area increases the rate of weathering.
Mineral Composition
Rocks made of harder minerals weather slower than rocks made of softer minerals
Climate
Physical and chemical weathering are affected by this.
Cold/moist
Physical weathering is dominant here
Hot/moist
Chemical weathering is dominant here
Time
As this goes by more weathering will occur
Humans
Excavation of land, minding, building, etc. affect rate of weathering because of these.
Soil formation
End product of weathering and biological activity
Parent Material
Bedrock.
Residual Soil
Soil is formed from the parent material and is of the same composition
Transported Soil
Parent material has been carried from elsewhere and deposited. Soil is also a different composition than where it is found
Arid climate
Climates that have thin soils, high in mineral content, low in organic matter. (Grand canyons, plateaus)
Humid climate
Climates have thick soils, high in organic matter, low mineral content
Organisms
Dead and decayed plant and animals add nutrients forming topsoil
Time
The longer the weathering, the deeper the soil.
Erosion
Transportation of sediments produced from weathered rock.
Gravity
Primary driving force for all transporting agents.
Angular
Sediments that fall short distances so they have sharp edges.
Mass Movement
Land slides, avalanches, mudflow, and slump.
Running Water
Primary agent of erosion on earth.
Gradient
Steeper the slope, the faster the water's velocity of this.
Discharge
The more ___ the grater/faster the stream velocity
Channel Slope
In a straight channel- water is fastest below the surface and in the center
Stream Load
The material a stream carries
Solution
Dissolved particles (ions)
Suspension
So tiny that they take a very long time to settle. They tend to "hang" in the water (clay, silt, sand)
Saltation
Larger sediments that are too big to be lifted so they bounce, roll, or are pushed along. (Abrasion is found when this happens)
Meanders
Bends or curves in the river
Oxbow
When meanders "close off" and leave behind a horseshoe-shaped lake
Young stream
Stream that has v-shaped valleys, rapids/waterfalls, steep slopes, no flood plains, and valleys are deepened
Mature stream
Stream where divides begin to round off, sediments build up, flood plain widens, and river begins to meander
Old Stream
A stream with very wide flood plains, land worn down to flat surface, pronounced river meanders, and oxbow lakes.
Watersheds/drainage basins
The area of land drained by one stream
Wind erosion
Wind carries small sediments, occurs mainly in deserts and along coastlines. Looks pitted and frosted. Freckles.
Wave action
Influenced by water depth, energy from winds/storms, and shape of shoreline.
Long-Shore Currents
Because waves strike the shore at an angle, the water near shore is pushed in one direction along the shore causing this. Sediments are carried in the same direction as the current
Glaciers
Mass of ice and snow. These are influenced by accumulation of ice and snow. Looks like there are scratches and grooves. Sediments are very unsorted. Form U-shaped valleys
Deposition
Process by which sediments are released, settled from or dropped from an erosional system. It occurs when the stream velocity decreases
Talus Cone
Sediment that is found at the base of a hill or mountain. Unsorted.
Sand bar
Cause of running water and wave action. Build up of sediment from wave action
Delta
Fan shaped deposit of sediment at the mouth of a river
Beach formation
Deposition takes place on the side of the grain that the long-shore current is coming from
Horizontal sorting
Occurs when a stream enters a lake; as kinetic energy decreases, the large, rounder, high density sediments are deposited near the mouth of the stream.
Sand dunes
From wind. The gentle slope faces the direction the wind came from.
Cross- Bedding
Diagonal sand deposits caused varying wind direction and velocity
Till
Unsorted sediment deposited by a glacier
Moraine
Till found along the sides or leading edge of a glacier
Drumlins
Elongated hills sculpted by a glacier's retreat; they indicate the glacier's flow.
Eskers
Long winding ridges of sand and gravel typically oriented parallel to ice flow. They were deposited by glacial melt water, in, on, or beneath the ice
Kames
Mounds or hills are created when drift fill a hole in a glacier. When the glacier recedes the mound is left behind
Kettle Lakes
Formed when large blocks of ice break from the face of the glacier and are buried in sediment. when these blocks melt, they leave circular depressions.
Erratics
Large boulders that were deposited when the glacier melted
Outwasn Plain
Melted water that washes out from under the glacier carrying sediments. Sorting will occur with a decrease in velocity.
Sediment
Rocks into smaller particles.
Colloid
Very small solid particles that are too small to be seen with an ordinary microscope, and too light to settle in water. Even in calm water they will stay suspended.
Soil
Combination of weathered rock and organic matter.
Humus
Decayed plant and animal material found in soil.
tributary
Smaller streams which flow into larger streams and rivers.
Divide
Ridge or section of a high ground between drainage basins