Weathering, Karst Landscapes, & Mass Movement

Question 1

What is denudation?

Answer 1

the process in which landforms are worn away and rearranged

Question 2

What is weathering?

Answer 2

the breakdown of rocks

Question 3

What is mass movement?

Answer 3

the movement of surface material

Question 4

What is erosion?

Answer 4

the transportation of material to different locations

Question 5

What is slope?

Answer 5

any inclined surface

Question 6

How does the weathering of rock on a slope effect material?

Answer 6

loosens material for erosion

Question 7

What three forces must be overcome before the movement of material can occur?

Answer 7

• frictional resistance
• inertia
• cohesion

Question 8

What is the angle of repose (4)?

Answer 8

• the maximum incline at which material can remain at rest before gravity begins to pull it downslope
• normal angle 33-37 degrees
• smaller particles have a more shallow angle
• larger particles have a steeper angle

Question 9

What is the difference between a stable and unstable slope?

Answer 9

• stable: the strength of the slope exceeds the force of gravity
• unstable: the strength of the slope does not exceed the force of gravity

Question 10

What is the difference between bedrock and regolith?

Answer 10

• bedrock: the parent rock from which regolith and soil develop
• regolith: unconsolidated rocky material covering the bedrock

Question 11

What is physical weathering and what does it do?

Answer 11

• breaks down rock without chemical alteration

- creates cracks which facilitate chemical weathering

Question 12

What are the three types of physical weathering?

Answer 12

• frost action: water gets between cracks in the rock and expands, breaking it apart
• salt crystal growth: moisture inside the rock evaporates, leaving dissolved mineral solts behind which crystallize, grow, and break the rock apart
• pressure release jointing: plutons created below the surface respond to a decrease in pressure above the surface by breaking into sheets

Question 13

What are the four types of chemical weathering?

Answer 13

• hydration: water permeates rock and becomes part of the chemical composition of the rock; rock breaks apart when water evaporates
• hydrolosis: chemical reaction occurs when water permeates rock
• oxidation: certain metallic elements in the rock combine with oxygen to form oxides
• carbonation: occurs when water vapor dissolves carbon dioxide, forming carbonic acid, which dissolves many minerals; made worse by human activity

Question 14

What is differential weathering?

Answer 14

process in which rock formations weather at different rates

Question 15

What are the five factors that influence weathering?

Answer 15

• rock composition and structure
• climate
• slope orientation
• subsurface water
• vegetation

Question 16

How does rock composition and structure influence weathering (3)?

Answer 16

• rock characteristics
• mineral composition
• presence of joints

Question 17

How does climate influence weathering (3)?

Answer 17

• warm/wet climates cause chemical weathering to occur faster
• high latitude climates likely to experience frost action
• the same rock type in different climates experiences different rates of weathering

Question 18

How does slope orientation influence weathering (3)?

Answer 18

• north/south facing impacts sunlight
• north-facing slopes cooler and wetter; more vegetation
• south-facing slopes warmer and drier; less vegetation

Question 19

How does subsurface water influence weathering (2)?

Answer 19

• height of water table

- movement/percolation of water

Question 20

How does vegetation influence weather?

Answer 20

can prevent weathering (shields regolith/bedrock from water) or promote weathering (releases organic acids and roots break rock apart)

Question 21

What is mass movement?

Answer 21

the movement of any surface material downslope

Question 22

What are the three characteristics of mass movement?

Answer 22

• moisture
• particle size
• speed

Question 23

What is the significance of slope (3)?

Answer 23

• mass movement only occurs on sloped surfaces
• mass movement only occurs when slope exceeds angle of repose
• different materials result in higher/lower likelihood of mass movement

Question 24

What are the the two mechanisms that trigger mass movement?

Answer 24

• water: as saturation increases, mass movement increases

- geomorphic threshold: the failure point of a slope

Question 25

What are the four types of mass movement?

Answer 25

• falls/avalanches: rockfalls and debris avalanches; fastest type; no moisture
• landslides: sudden, cohesive mass movement of regolith and bedrock; faster type; no moisture
• flows: earthflows, mudflows, and debris flows; slower type; moisture
• creep: the persistent and gradual downward movement of soil; slowest type; moisture

Question 26

What is karst topography and what does it look like (4)?

Answer 26

• common in areas with limestone rock: calcium carbonate dissolves in water
• irregular, pitted surface
• poor surface drainage and cavern formation
• originated from Krs Plateau in Slovenia

Question 27

Where are karst formations located in the U.S. (4)?

Answer 27

• central Florida
• central Texas
• Shenandoah, Virginia
• Mammoth Cave, Kentucky

Question 28

What are the four conditions required for karst topography to form?

Answer 28

• limestone rock which contains at least 8% calcium carbonate
• joint pattern: cracks which allow water to drain inward
• zone of air between ground surface and water table
• vegetation to supply organic acids to enhance dissolving process

Question 29

What are the three features of karst landscapes?

Answer 29

• sinkholes: circular depressions
• limestone towers: blocks of limestone resistant to erosion
• caverns: caves formed within limestone rock

Question 30

What are seven features which can occur in caverns?

Answer 30

• column
• drip curtain
• rock fall
• sinkhole
• solution pipe
• stalactites (ceiling)
• stalagmites (ground)