Chapter 16 Gradation, Weathering and Mass Movement

1
Study Guide Chapter 15
1. What processes does gradation
include. 2. Describe erosion and
deposition. 3. List the gradational agents. What
are the energy sources for the gradational
agents? 4. Describe the two basic types of
weathering. 5. What contributes to the mechanical
disintegration of rocks? How? 6. Explain how
gradation and tectonics shape the earth's
landscape. 7. Explain weathering by the process
of frost wedging, salt wedging, exfoliation, and
weathering by organic activity. 8. What are
evaporites?
2
Study Guide Continued
9. Explain the weathering process of solution,
oxidation, and hydrolysis. 10. What is the most
outstanding examples of differential
weathering? 11. Describe climatic conditions
which speed up chemical weathering
rates. 12. Describe slump, mudflow, landslide,
rockslide, and rock fall. 13. Define
regolith. 14. Compare and contrast slow mass
movement and rapid mass movement. 15. Diagram and
explain the mass movement process of "creep."
3
Gradation, Weathering and Mass Wasting

• Gradation
• Erosion Removal of material
• Deposition Filling of depressions
• Transportation of materials
• Gradational agents
• Water, wind, ice
• All agents are powered by solar radiation and
  gravity

4
Weathering

• Material decomposed to prepare for easy
  transportation
• Types of weathering
• Physical/Mechanical
• Disintegrates rock without altering chemical
  composition.
• Chemical
• Rocks decay by a variety of chemical reactions.

5
Fig. 15-1, p. 424
6
Weathering

• Rounded rocks- chemical
• Jagged angular rocks- physical

7
Weathering factors

• Structure and composition of the rock
• Climate
• Configuration of the land surface
• Vegetative cover

8
Physical Weathering

• Frost wedging
• Water freezes in cracks of rocks. When water
  freezes it expands. Predominately occurs above
  the tree line. Figure 15.11 shows talus cones
• Salt wedging
• Formation of crystals. Predominately occurs on
  rocky marine coasts
• Exfoliation
• Peeling off of concentric layers. Half Dome in
  Yosemite Valley

9
exfoliation
10
Contributors to Physical Weathering

• Joints and fractures in the rock
• Plants
• Animals
• Human activities

11
Chemical Weathering

• New minerals form finer softer material. Easier
  to transport.
• Forms
• Addition of water
• Addition of a weak acid
• Factors that affect chemical weathering
• High temperatures and water available
• What climate is this?

Hot Humid Tropical Rainforest
12
Physical
chemical
13
Chemical Weathering

• Minerals dissolved in water are said to be in
  solution.
• Mineral salts immediately soluble in water are
  called evaporites. They precipitate when the
  water becomes saturated with them.
• Oxidation- Chemical union of oxygen with another
  substance. Examples- limestone turns yellow or
  formation of red from iron oxide.
• Hydrolysis- Chemical union of water with another
  substance.

14
Some Facts

• Grand Canyon most outstanding feature of
  differential weathering.
• Regolith-Weathered surface material that covers
  bedrock.

15
Regolith and Bedrock
16
Rapid Mass Movement

• Rapid Mass Movement is visible and dramatic.
• Slump- Curved backward rotation. Frequent in
  clay rich California.
• MudFlow- More fluid than earth flow. Associated
  with fires and then torrential rains or volcanoes
  where the mudflow is called a lahar.

17
Fig. 15.29
18
Rapid Mass Movement

• Landslide-Mass of material that moves as a unit.
  Carries regolith and masses of bedrock.
  Conditions Steep mountains and heavy rain or
  earthquakes.
• Rockfall-Individual rock or several rocks that
  fall down slope. Rock fragments can be small or
  large.

19
Rockfall
20
Slow Mass Movement

• Creep
• Solifluction
• Thawed area of permafrost. What biome?
• Unfrozen part of the soil becomes watersoaked
  creating a soggy mass that sags slowly downslope
  in response of gravity.

Tundra
21
Creep
Tilted Telephone poles
Figs. 15.31 32
Broken walls
Curving plant growth
22
(No Transcript)