Chapter 15

Question 1

Mechanical weathering

Answer 1

physical disintegration of rock without changes to its chemical composition

Question 2

frost wedging

Answer 2

freeze-thaw action of water; ice wedges downward in openings, ice melts and water falls further down large opening, process repeats; frost shattering

Question 3

salt wedging

Answer 3

salt left behind from evaporated water collects and pries apart rock openings

Question 4

temperature changes

Answer 4

diurnal and seasonal temperature fluctuations modify volumes slightly; fracturing of rock over long time periods

Question 5

Exfoliation

Answer 5

curved layers peel off of bedrock; create exfoliation dome; due to weathering, exfoliation can occur in granite through expansion—the material on top of the item is no longer present and no longer provides pressure

Question 6

Chemical Weathering

Answer 6

decomposition of rock material through chemical alteration of minerals; greater surface area is decomposed faster; MOISTURE IS REQUIRED

high temp and precipitation increases chemical weathering

Question 7

Oxidation

Answer 7

oxygen is combined with metallic elements in minerals to form new products

Question 8

Biotic Weathering

Answer 8

plants and animals alter rock structure; impact of lichens and burrowing of animals

Question 9

Mass weathering

Answer 9

process by which weathered material is moved short distances by gravity

Question 10

factors affecting weathering

Answer 10

angle of repose, impact of water on lubrication of rock material

Question 11

Fall

Answer 11

rockfall, talus/scree;

talus apron: uniform accumulation of rockfall material

talus cones: material tends to collect in cone shaped heaps

Question 12

Slide

Answer 12

landslide, instantaneous mass slope collapse with NO FLUID flow lubrication
- SLUMP: rotation of sliding materials
- initiated from added weight from rainfall or earthquakes
- rock or avalanches
- lost material leaves a land scar
- damming of valley streams

Question 13

Flow

Answer 13

wasting initiated or enhanced by the addition of water; water is the primary force, clay enhances the motion
- earthflows: water saturated land moves downhill
- mudflows: originated in arid basins; muddy downslope flows that can accumulate in large rock material

Question 14

Creep

Answer 14

unobtrusive downslope flow of soil and regolith; freeze/thaw and wet/dry effects
- principle variables: slope angle, vegetative cover, moisture supply
- soilfluction: soil flowage
- terracettes