Chapter 4: Weathering, Erosion, & Mass Wasting

Question 1

What is Mass Wasting?

Answer 1

Transfer of sediment down slope under the influence of gravity

Question 2

What is the definition to weathering?

Answer 2

Disintegration and decomposition of material at or near surface; happens in place

Question 3

What is Erosion?

Answer 3

transportation of material by a mobile agent (wind, water, or ice)

Question 4

What is a Landslide Scar?

Answer 4

evidence of previous mass wasting at the same site

Question 5

Important triggering factors of mass wasting include?

Answer 5

1) Saturated material w/ water
2) Removal of anchoring vegetation (EX: wildfires)
3) Ground shaking from earthquakes, ect.
4) Removal of supporting material @ base of slope (undercutting)
5) Over steeping of slopes

Question 6

Mass wasting process are defined by what?

Answer 6

1) material involved- sediment, soil, or rock
2) The type of movement of material: fall, slide, flow
3) the rate of movement: fast slow

Question 7

The types of movement in the mass wasting materiel?

Answer 7

Fall: vertical free-fall of rock/ sediment

Slide: material moves downslope along well-defined surface

Flow: material moves as a viscous fluid

Question 8

The rate of movement within mass wasting?

Answer 8

Fast: seconds or minuets

Slow: months, years, or decades

Question 9

The four forms to mass wasting?

Answer 9

A) Slump
B) Rockslide
C) Debris flow (or mudflow) 
D) Earthflow 
E) Creep
F) Slolifluction

Question 10

What is a slump?

Answer 10

Rapid movement along a curved surface
Occurs along over- steepened slopes
Also known as a rotational landslide

Question 11

What is a rockslide?

Answer 11

Rapid movement

Blacks of bedrock slide down a slope

Question 12

What is a Debris flow (or mudflow)?

Answer 12

Rapid flow of debris with water
Often confined to channels

Lahars= debris flows composed mostly of volcanic materials

Question 13

What are Engineered structures?

Answer 13

Safety structures can be built to improve slope stability or to reduce movement hazards.

Question 14

Five Examples of Engineered structures

Answer 14

1) Retaining walls: barriers that pin base and trap rock
2) Covers: fencing or coating that drapes over the
outcrop
3) Rock Staples: Rods drifted into rock to hide loose
fencing
4) Avalanche sheds: structures that shunt avalanche
snow
5) Controlled blasting: intentional removal of dangerous
rock

Question 15

What is earthflow?

Answer 15

Rapid movement
Occurs when water saturates the soil
Typically occurs on hillsides in humid regions during
heavy rain or snow melt

Question 16

What is Creep in terms of the mass wasting process?

Answer 16

Slow downslope movement of soil and regrowth

Question 17

What is Solifuluction in terms of mass wasting process?

Answer 17

Slow movement in area underlain by permafrost (permanently frozen ground)
Upper solid layer becomes saturated and slowly flows over the frozen surface below

Question 18

What is permafrost?

Answer 18

Permanently frozen ground

Question 19

Two types of weathering?

Answer 19

Mechanical weathering- physical breakdown of rocks into smaller pieces

Chemical weathering- alters internal structure of minerals by removing or adding elements

Question 20

What is the process of Mechanical weathering?

Answer 20

A) Frost wedging- “freeze-thaw” effect
B) Unloading and exfoliating- removal of overlying sediment and rock
C) Biological activity- plants and aniamals help to mechanically weather rocks

Question 21

Angular rock debris fragments on slope, is called what?

Answer 21

Talus

Question 22

What is the most important agent to Chemical weathering?

Answer 22

Water!
Oxygen dissolves and oxidizes materials (speeds up chem. weath.)
CO2 dissolved formed carbolic acid and alters rocks/minerals

Question 23

The two weathering rate factors?

Answer 23

1) Rock characteristics- mineral composition/ solubility of rock. Physical features speed up breakdown process.
2) Climate- temp and moisture are crucial factors.

Question 24

What type of weathering is the slowest in cold areas and most effective in warm moist areas?

Answer 24

Chemical weathering

Question 25

What is differential weathering?

Answer 25

Caused by variations in rock composition.

Creates unusual/ spectacular rock formations and landforms

Question 26

Soil is the combination of what?

Answer 26

1) Organic matter
2) Mineral matter
3) Water
4) Air

Question 27

What are the controls of Soil Formation?

Answer 27

CL. O. R. P. T

1) Climate
2) Organisms
3) Slope (relief)
4) Parent material
5) Time

Question 28

What is the most influential in Soil Formation?

Answer 28

Climate because it determines nature and intensity of weathering that occurs over geographic areas

Question 29

Organisms act to churn up the soil is called what?

Answer 29

Bioturbation

Question 30

Residual soil and Transported soil are what type of parent material?

Answer 30

RS- parental material is the bedrock

TS- parent material has been carried elsewhere and deposited

Question 31

Two factors of the Soil formation: Slope?

Answer 31

Angle of slope:
steep slopes often have poorly developed soil and optimum relief for soil to form on flat upland surface

Orientation (direction of slope:
influences soil temp and moisture

Question 32

Another word for relief

Answer 32

Topography

Question 33

The Natural Rates of Soil Erosion depends on?

Answer 33

Soil characteristics- climate, slope

Type/ amount of vegetation- more vegg in an area, less erosion will occur

Question 34

Soil Erosion and Sediment can cause what?

Answer 34

Water reservoirs to fill with sediment

Contamination of water by pesticides and fertilizers

Question 35

When was the Dust Bowl?

Answer 35

known as the ‘dirty thirties’

1937 near Elkhart, Kansas