Lecture 5

Question 1

External processes ?

Answer 1

Weathering, mass wasting and erosion

Question 2

Internal processess ?

Answer 2

Plate tectonics, mountain building & volcanic acitvity.

Question 3

Weathering ?

Answer 3

Physical breakdown disintegration and chemical alteration of rock near or at earth’s surface

Question 4

Mass wasting ?

Answer 4

Transfer of rock and soild downslope by gravity

Question 5

Erosion ?

Answer 5

Physical removal of material by water, wind or ice

Question 6

Mechanical weathering ?

Answer 6

Breaking of rocks into smaller pieces by physical forces

Question 7

Chemical weathering ?

Answer 7

Involves chemical transformation of rock into one or more new compounds

Question 8

Frost wedging ?

Answer 8

Water works its way into crack in rock, freezes, expands, and enlarges the openings, breaking of rock
Creates large piles of borcken rock called talus slopes

Question 9

Sheeting ?

Answer 9

Process by which large masses of igneous rock such as granite are exposed by erosion, and concentric slabs beging to break loose

Question 10

What is the most important agent involved in chemical weathering ?

Answer 10

Water

Question 11

Dissolution ?

Answer 11

Easiest type of decomposition

Question 12

Halite ?

Answer 12

One of the most water-soluble mineral

Question 13

Oxydation ?

Answer 13

Any chemical reaction in which an element loses electrons
Presence of water speeds the process

Question 14

How do silicates primarily decompose?

Answer 14

hydrolysis

Question 15

What is hydrolysis?

Answer 15

Reaction of any substance with water.

Question 16

What happens during hydrolysis in silicate minerals?

Answer 16

Hydrogen ion attacks and replaces other positive ions in the mineral

Question 17

Can you provide an example of hydrolysis?

Answer 17

• K-feldspar in granite = clay minerals
• Soluble salt
• Silica

Question 18

What are two main alterations caused by chemical weathering?

Answer 18

• Decomposition of unstable minerals
• Generation/retention of stable materials

Question 19

What are the changes causes by spheroidal weathering?

Answer 19

Physical changes : rounding of corners/edges, caused by water flowing through joints.

Question 20

Which rocks are relatively resistant to weathering?

Answer 20

Rocks with silicate minerals (granite)

Question 21

Which rocks readily dissolve in weakly acidic solutions?

Answer 21

Rocks with calcite (marble, limestone)

Question 22

How do silicate minerals weather?

Answer 22

In the same order as their order of crystallization.

Question 23

What are crucial factors affecting the rate of chemical weathering?

Answer 23

Temperature and moisture.

Question 24

What is the best environment for chemical weathering?

Answer 24

Warm temperatures and abundant moisture.

Question 25

Where is chemical weathering ineffective?

Answer 25

In polar regions and arid regions.

Question 26

What is differential weathering?

Answer 26

The uneven weathering of rock.

Question 27

What results from differential weathering?

Answer 27

Many unusual rock formations and landforms, such as the hoodoos of Drumheller, Alberta.

Question 28

What are important influencing factors in differential weathering?

Answer 28

The number and spacing of joints, composition, and size of particles.

Question 29

How is soil described in relation to Earth?

Answer 29

Soil is called “the bridge between life and the inanimate world.”

Question 30

What is soil considered to be?

Answer 30

An interface—a common boundary where different parts of Earth’s system interact.

Question 31

How sensitive is soil to environmental changes?

Answer 31

Soil is highly sensitive to environmental changes.

Question 32

What is regolith?

Answer 32

The layer of rock and mineral fragments produced by weathering that covers Earth’s surface.

Question 33

How is soil defined?

Answer 33

Soil is a combination of mineral and organic matter, water, and air that supports plant growth.

Question 34

What is humus?

Answer 34

The organic component of soil.

Question 35

What are the five controls of soil formation?

Answer 35

Parent material, time, climate, plants and animals, and topography.

Question 36

What is parent material?

Answer 36

The source of weathered mineral matter.

Question 37

How do residual and transported soils differ?

Answer 37

Residual soils form from underlying bedrock, while transported soils form on unconsolidated sediment transported from elsewhere.

Question 38

How does time affect soil formation?

Answer 38

The longer a soil has been forming, the thicker it becomes, and the less it resembles the parent material.

Question 39

What is the most influential control on soil formation?

Answer 39

Climate, with key factors being temperature and precipitation.

Question 40

How do plants and animals influence soil?

Answer 40

They influence soil’s physical and chemical properties, supply organic matter, and mix soil through activities like burrowing.

Question 41

How does topography influence soil formation?

Answer 41

Steep slopes often have poorly developed soils, while lowland areas have thick, dark soil rich in organic matter.