Week 10 – Weathering & Erosion (review the PowerPoint slides!)

Question 1

Know how weathering impacts the Rock Cycle.

Answer 1

Weathering: processes that decompose rocks and convert them to loose gravel, sand, and clay

Question 2

What are the three primary types of weathering

Answer 2

Physical
Chemical
Biological

Question 3

In Physical weathering, rock is broken down, but is there any change to its mineral composition?

Answer 3

No

Question 4

What are the 5 types of physical weathering – be able to provide examples of such.

Answer 4

Pressure-release fracturing- sheet joints (exfoliation)
Abrasion- ventifacts
Freeze-thaw- talus slopes
Hydraulic action- Cliffs
Chemical-Growth of salts

Question 5

Name three elements that can cause abrasion of rock – be able to name examples of each.

Answer 5

Wind- ventifacts
Ice- talus slopes
Water- cliffs

Question 6

What is pressure-release fracturing?

Answer 6

Pressure-release fracturing is when rock is uplifted and exposed causing the rock to expand and crack, thus weathering the rock.

Question 7

What causes Talus slopes?

Answer 7

Freeze-thaw due to freezing water getting into cracks and expanding when frozen (ice-wedging)

Question 8

What is Chemical weathering, and what happens to the mineral in the original rock?

Answer 8

Chemical weathering is the transformation from one mineral into another via a chemical process.

Question 9

Know the three types of chemical weathering and be able to name examples of each.

Answer 9

Hydrolysis- feldspar to clay
Oxidation- Iron+02=rust
Dissolution-karst formations (dissolution)

Question 10

What are Karst formations, and how do they form?

Answer 10

Karst formations are sinkholes and occur when carbonic acid dissolves the mineral calcite (found in limestone)

Question 11

What percent of the US landscape is considered to have Karst topography?

Answer 11

20%

Question 12

How does biological weathering break down rock and help create soil? Name at least three ways.

Answer 12

Linchen and other organisms influence moisture and break down rock
Tree roots
Co2 released by plants turns carbonic and weakens rocks

Question 13

Know that soil is the product of weathering rock into mineral particles and added organic material – i.e., bacteria, fungi, and other organisms. What percentage of soil comprises minerals, organic matter, air, and water?

Answer 13

Minerals: 45%
Organic material: ~5%
Air and water (empty space): 50%

Question 14

This biologically important chemical is absorbed from the air by bacteria in soil and thus made available to plants and animals.

Answer 14

Nitrogen

Question 15

What type of weather is most common in areas with low temperatures and low rainfall, and which is more common in areas with higher temperatures and higher rainfall?

Answer 15

Low temp and low rainfall: Physical weathering
high temp and high rainfall: Chemical weathering

Question 16

What are the four types of erosion? Be able to provide examples of each.

Answer 16

Mass wasting- talus slope/rockfall
Water erosion- river delta
Glacial- terminal moraine
Wind erosion- sand dunes