Weathering, Karst Landscapes, & Mass Movement Flashcards
What is denudation?
the process in which landforms are worn away and rearranged
What is weathering?
the breakdown of rocks
What is mass movement?
the movement of surface material
What is erosion?
the transportation of material to different locations
What is slope?
any inclined surface
How does the weathering of rock on a slope effect material?
loosens material for erosion
What three forces must be overcome before the movement of material can occur?
- frictional resistance
- inertia
- cohesion
What is the angle of repose (4)?
- 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
What is the difference between a stable and unstable slope?
- stable: the strength of the slope exceeds the force of gravity
- unstable: the strength of the slope does not exceed the force of gravity
What is the difference between bedrock and regolith?
- bedrock: the parent rock from which regolith and soil develop
- regolith: unconsolidated rocky material covering the bedrock
What is physical weathering and what does it do?
- breaks down rock without chemical alteration
- creates cracks which facilitate chemical weathering
What are the three types of physical weathering?
- 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
What are the four types of chemical weathering?
- 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
What is differential weathering?
process in which rock formations weather at different rates
What are the five factors that influence weathering?
- rock composition and structure
- climate
- slope orientation
- subsurface water
- vegetation
How does rock composition and structure influence weathering (3)?
- rock characteristics
- mineral composition
- presence of joints
How does climate influence weathering (3)?
- 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
How does slope orientation influence weathering (3)?
- north/south facing impacts sunlight
- north-facing slopes cooler and wetter; more vegetation
- south-facing slopes warmer and drier; less vegetation
How does subsurface water influence weathering (2)?
- height of water table
- movement/percolation of water
How does vegetation influence weather?
can prevent weathering (shields regolith/bedrock from water) or promote weathering (releases organic acids and roots break rock apart)
What is mass movement?
the movement of any surface material downslope
What are the three characteristics of mass movement?
- moisture
- particle size
- speed
What is the significance of slope (3)?
- 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
What are the the two mechanisms that trigger mass movement?
- water: as saturation increases, mass movement increases
- geomorphic threshold: the failure point of a slope
What are the four types of mass movement?
- 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
What is karst topography and what does it look like (4)?
- 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
Where are karst formations located in the U.S. (4)?
- central Florida
- central Texas
- Shenandoah, Virginia
- Mammoth Cave, Kentucky
What are the four conditions required for karst topography to form?
- 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
What are the three features of karst landscapes?
- sinkholes: circular depressions
- limestone towers: blocks of limestone resistant to erosion
- caverns: caves formed within limestone rock
What are seven features which can occur in caverns?
- column
- drip curtain
- rock fall
- sinkhole
- solution pipe
- stalactites (ceiling)
- stalagmites (ground)
