Module 8

Question 1

describe the processes of rock weathering: compare and contrast physical and chemical weathering processes.

Answer 1

Weathering processes break down rock at the Earth’s surface and to some depth below the surface

Physical weathering process, also called mechanical weathering, is the process of rock disintegration without any chemical alteration
Chemical weathering process refers to the decomposition and decay of the constituent minerals in rock due to chemical reactions, always in the presence of water

Question 2

Define mass movement and describe the main processes involved; identify examples of mass movement landforms

Answer 2

Mass movement (or mass wasting) is the process involved in erosion, transport, and deposition of earth materials in hillslopes under the influence of the force of gravity
Classification is based on: type of material; nature of motion
Ex) soil/rock creep, rockfall, landslides, flows, avalanches

Question 3

Discuss the role of mass movement processes as natural hazards

Answer 3

Falls involve the release of a volume of rock or regolith from a steep slope, its free-falling through the air, and its impact at the base of the slope; a very rapid process;
extremely dangerous compared to creeps

Question 4

Discuss the physical properties of rock and regolith contribute to the strength of these materials.

Answer 4

Faults and joints in rocks weaken them and make the material more susceptible to physical and chemical weathering.
Bedrock undergoes continual weathering and is transformed into regolith. Regolith forms the parent material from which soils are developed.

Question 5

What is the relation between stress and strength that facilitates mass movement?

Answer 5

Shear strength: N=Wcosθ =mgcosθ
Shear stress: T=Wsinθ = mgsinθ

If N>T it is stable and there is no mass movement
if N

Question 6

Describe briefly the origin of karst landscapes.

Answer 6

Karst topography refers to a region of limestone or gypsum bedrock characterized by surface depressions (dolines) and well developed solution channels underground (caverns) created by chemical weathering