GeoClassroom Physical Geology Historical Geology Structure Lab

Physical Geology

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Weathering and Erosion

Weathering:

The disintegration or decomposition of rx on the Earth's surface.

Mechanical Weathering:

- breaks rocks by physical forces into smaller and smaller pieces, each retaining the characteristics of the original piece.

- with each new pieces, the area available for more weathering increases, so the process increases logarithmicly
- four important processes: Frost wedging, Unloading, Thermal expansion, and Organic activity.
- also: wind, glacial ice, running water.

Chemical Weathering:

- alters internal structure of mins by removing/adding elements.

- original material erodes into something stable in the surface environment.
- Water is the most important agent in chemical weathering.

- Quartz is very resistant, doesn't weather easily.

-Ends up being able to be transported in rivers great distantces without being broken down. That's why beaches tend to be quartz-rich (sand is quartz).

- resistance to weathering is just the opposite of Bowen's Reaction Series.

- climatic factors (temp, avail of water, altitude, etc. affect the rate of weathering.

- chemical weathering can cause angular fragments in a rock mass to become rounded and take on a spherical shape.


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