Weathering + Erosion

Question 1

What is weathering?

Answer 1

Breakdown of rock at or near the Earth’s surface.

Question 2

‘Mass wasting’?

Answer 2

Transfer of rock and soil downslope by gravity.

Question 3

What is erosion?

Answer 3

Removal of material by water, wind or ice.

Question 4

What are the two types of weathering?

Answer 4

Mechanical (breakdown of rocks into smaller pieces by physical forces).

Chemical (transformation of rock into one or more new compounds).

Question 5

Provide an example of mechanical weathering.

Answer 5

Rock joints

Rocks go through an ongoing process over thousands of years of water seeping through cracks and crevices (joints) freezing during winter or major glaciations, and cracking the stone such that they weather away and form staggered shapes.

Biological activity

Plants, burrowing animals and humans will cause disintegration in rocks.

Others:

• Frost wedging
• Unloading (sheeting, exfoliation domes, temperature cycling and stress relief)

Question 6

What are three types of chemical weathering?

Answer 6

Dissolution (of salt, soluble ions, released from rock aided by acidity, limestone pavement and stalactites).

Oxidation (loses electrons, iron in mafic minerals).

Hydrolysis (H+ detached from H2O and replaces other positive ions, feldspar to clay).

Question 7

‘Differential weathering’?

Answer 7

Masses of rock weathering at different rates.

Question 8

TRUE or FALSE

Rates of crystallization correspond to rates of weathering.

Answer 8

TRUE

Question 9

What is the trend between grain size and disturbance?

Answer 9

Finer grain can lead to easily disturbed substances. For example, clay is made of very fine grain, which renders it sensitive to disturbance and can fail catastrophically. However, because of this characteristic, clay is a good landfill base liner.

Question 10

Describe the two types of stream flow and how they play a part of in the transportation of sediments.

Answer 10

Laminar flow (slow, smooth channel, suspended in the middle of the lake).

Turbulent flow (fast, rough channels in the very bottom and shallow shores of the lake).

Turbulent flow will swish around the bedload, while the suspended load will travel via laminar flow. Gravel will be easily displaced due to grain size but won’t travel very far due to mass. Clay will not be easily displaced, but when wedged out of the stream bed, it will travel very very far.