Physical Geology

Question 1

Erosion

Answer 1

Involves removing weathered materials from their place of origin-by running water or wind.

Question 2

Weathering

Answer 2

The mechanical and chemical alteration of Earth materials at or near the surface.
* soluble salts
* ions in solution
* solid particles

Question 3

Mechanical Weathering Processes

Answer 3

• Frost action
• Pressure release
• Thermal expansion and contraction
• Crystal growth
• Activities of organisms

Question 4

The products of mechanical weathering are ___ as their parent materials.

Answer 4

chemically the same

Question 5

Mechanical Weathering - Frost Action

Answer 5

• When water freezes in cracks in rocks it expands, thus exerting pressure and opening the cracks wider.
• Repeated freezing and thawing disaggregates rocks into angular pieces that may tumble downslope and accumulate as talus.

Question 6

Mechanical Weathering - Sheet Joints

Answer 6

• Fractures that are roughly parallel to rock surfaces, especially rocks at the surface that formed under great pressure at depth.
• These joints form by outward expansion in response to pressure release.

Question 7

Mechanical Weathering - Plants

Answer 7

• Any organic activity such as tree roots growing in cracks contributes to mechanical weathering.
• Organic acids and the tendrils of mosses and lichens aid in the chemical alteration of parent material.

Question 8

Chemical Weathering

Answer 8

• These processes cause a change in the chemical composition.
  The parent material is transformed into:
• Ions in solution,
• Soluble salts and
• Clay minerals.

Question 9

Chemical Rate - Climate

Answer 9

Hot and wet environments accelerate
chemical weathering.
* Reactions
* Solution
* Oxidation
* Hydrolysis

Question 10

Chemical Rate - Surface Area

Answer 10

• Mechanical weathering enhances chemical weathering.
• By increasing the surface area for chemical reactions.
• Chemical weathering is a surface process, the more surface exposed, the faster the weathering.