Weathering & Erosion
description
Transcript of Weathering & Erosion
![Page 1: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/1.jpg)
Weathering & Erosion
![Page 2: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/2.jpg)
Weathering the process that produces
change in the surface of rocks exposed to the atmosphere
and/or hydrosphere.
![Page 3: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/3.jpg)
Two Types OF Weathering:•Physical weathering is breaking rock by force.
•ex: hitting, scratching, cracking
•Chemical weathering is where the rock material is changed into another substance by reacting with a chemical.
![Page 4: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/4.jpg)
•Frost action •(ice wedging)-
1.Water seeps into small cracks in rocks. 2.When the water freezes it expands creating great pressure. 3.The crack widens and allows water to seep deeper into the rock.
![Page 5: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/5.jpg)
TYPE OF PHYSICAL WEATHERING?
![Page 6: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/6.jpg)
•Plant action- 1.Tiny root hairs seek out small cracks and pits in rock. 2.Once the root hairs find a place they grow and expand. 3.The expansion causes great pressure and cracks the rock.
![Page 7: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/7.jpg)
TYPE OF PHYSICAL WEATHERING?
![Page 8: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/8.jpg)
•Exfoliation 1.Rocks formed
deep in the Earth are made under high pressure.
2.When the pressure is released the rocks expand & crack.
3.May also be caused by alternate heating and cooling of rocks by weather conditions.
![Page 9: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/9.jpg)
•Abrasion- rubbing by other rocks.
![Page 10: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/10.jpg)
CHEMICAL WEATHERINGRock reacts with water, gases and solutions (may be
acidic); will add or remove elements from minerals. 1. Dissolution (or solution)
- also includes leaching2. Oxidation 3. Hydrolysis 4. Biological Action5. Spheroidal
![Page 11: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/11.jpg)
•Oxidation- •Oxygen in the atmosphere chemically reacts with minerals. •ex.: rusting of a nail
![Page 12: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/12.jpg)
•Water (hydrolysis)•Minerals are dissolved in water. •ex.: Halite, calcite
![Page 13: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/13.jpg)
BIOLOGICAL ACTION•Lichens, fungi, and other micro-organisms •Chemically and physically change rock
![Page 14: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/14.jpg)
•Acid- Carbonic acid:
•C02 dissolves in rain water forming a weak acid. •Sulfuric Acid also
![Page 15: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/15.jpg)
![Page 16: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/16.jpg)
ACID LEACHING
![Page 17: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/17.jpg)
SPHEROIDAL WEATHERING
•chemical weathering of jointed rocks. •weather to form spherical shapes
![Page 18: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/18.jpg)
FACTORS AFFECTING WEATHERING•Type of material – both are from 1780’s; one is slate, the other is marble. Which is which? Why is there a difference?
![Page 19: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/19.jpg)
RATES OF WEATHERING WILL BE INFLUENCED BY:
Surface area exposed - weathering occurs on the surface. More surface exposed, the faster the weathering will occur.
![Page 20: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/20.jpg)
A full, solid block has the least surface area.
The interior is safe from exposure.
A smashed piece has greatest surface area exposed. The interior can now be attacked.
![Page 21: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/21.jpg)
EROSION•Movement / transportation
•Wind, water, glacier
•Mast Wasting - Movement of large amounts of material downhill under gravity
•Creep •Mudflows •Slump •Rockfalls •Landfalls
•Avalanches
![Page 22: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/22.jpg)
4 TRIGGERS OF MASS MOVEMENTS:•Water—saturates surface materials by heavy rain or
rapid snow melt; lubricates particles so they move easier•Oversteepened slopes—a slope remains stable only up to 25-40° based on particle type & size•Removal of vegetation—plants stabilize slopes because roots bind soil & regolith together; w/o plants soil moves easily•Earthquakes—can dislodge huge amounts of rock and unconsolidated material
![Page 23: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/23.jpg)
• Types of Mass Movements are based on the kind of material that moved, how it moved, and the speed of movement
![Page 24: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/24.jpg)
Types of Mass Movements:•Rockfall—rocks freefall through air •Rockslide—a block of rock and
loose material moves suddenly along a flat, inclined surface; common in high mountain areas; fastest moving mass movement (200 km/hr)
![Page 25: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/25.jpg)
Types of Mass Movements:• Slump—downward movement of
material on a curved surface; does not move fast or far
• Flow—movement of material containing a large amount of water; moves like a thick liquid (think cake mix)
• Earthflow—moves slowlyMudflow—moves quickly
![Page 26: Weathering & Erosion](https://reader035.fdocuments.us/reader035/viewer/2022070423/5681660d550346895dd94bfe/html5/thumbnails/26.jpg)
Types of Mass Movements:• Creep—caused by alternating
expansion & contraction of the ground (freeze/thaw); slowest mass movement (1mm-3cm/yr); cannot be directly observed