Chapter 15- Preliminaries to Erosion: Weathering and mass Wasting

Question 1

Why are rock openings/jointing important in weathering?

Answer 1

Mechanical weathering - frost wedging, salt wedging, temperature changes, exfoliation - Chemical weathering - oxidation, hydrolysis, carbonation (‘rotting’ is most common in humid areas) - Types of biological weathering - plants and animals

Question 2

After rock weathers in place [in situ], what happens then?

Answer 2

Soil, sand, regolith, and rock move downslope typically as a mass, largely under the force of gravity, but frequently affected by water.

Question 3

Mass Wasting influences?

Answer 3

Angle of repose (slope steepness), available water, amount of clay, earthquakes.

Question 4

Types of mass wasting are classified by speed and the amount of water involved

Answer 4

Fall - rock moving through air via gravity (evidenced by talus deposit at base of cliff) Slide - sudden detaching of rock from steep slope, still in contact with slope Slump – rotational slip of solid mass of earth material lubricated by water Flow – earthflow (wet, fine-grained material) and mudflow (wetter, faster moving) Creep – tilted fences posts or leaning headstones. Solifluction: freeze-thaw cycle in Tundra.