Karst Flashcards
What do exogenic (external) processes do to the landscape?
These processes wear down the landforms created by endogenic processes
What is denudation?
Wearing down the land
What are some processes that wear down the land?
- Weathering
- Erosion
- Transportation
- Mass movement
- Deposition
What are some agents that wear down the land?
- Wind and Air
- Water
- Waves
- Ice
- Gravity
What is weathering?
the physical, biological, and chemical processes that break rock down into particles (soils, sediments, and other deposits)
What is erosion?
When particles are transported (by wind, water, ice, gravity), the process becomes erosion. Erosion can be a major factor in both creating and destroying landforms
What is mass movement?
When particles are moved downslope by gravity. When particles end up in place, they are considered deposits
Where does weathering occur?
At surface and subsurface
What does the weathering of bedrock and the addition of organic matter produce?
Soil
What are some factors that control soil formation?
- Parent material (underlying rocks)
- Climate
- Topography
- Biological factors
- Time
How does soil form through time?
Slide 10
What are sediments? How do they compare to soil?
Sediments are eroded materials that are transported to a place, while soils form in placeq
What is differential weathering? Why does this happen?
When weathering is not even across all places. This is due to different climate and rock types
What are some factors that influence weathering?
- Rock composition & structure
- Climate
- Soil-water and Groundwater
- Vegetation
- Time
What are the 3 main weathering processes?
- Biological
- Physical
- Chemical
What is biological weathering?
Organisms assist in physical and chemical weathering in breaking down rock
What is physical weathering?
Rocks are broken up by mechanical processes without chemical alteration
What are the three types of physical weathering?
A. Frost-Wedging
B. Crystallization
C. Exfoliation
What is frost weathering?
- water filled crack
- freezes to ice
- breaks rock
Where does frost weathering occur?
Occurs where its cold enough to get hard freezes and ice
D and E climates and high elevation
What is crystallization?
water evaporates, leaving mineral salts that grow and exert force (physical NOT chemical weathering)
Where does crystallization occur?
Only in Arid regions
What is exfoliation?
Exfoliation (“unloading”)—granite rocks (igneous; have large crystals by cooling slowly deep in the earth) break into leaves or sheets due to expansion and pressure release after uplift and/or when erosion decreases weight of overburden
Where can exfoliation occur?
Can occur anywhere there are granites exposed at the surface
What is a monadnock?
hill or mountain rising conspicuously above the surround plain
What is chemical weathering?
is the decomposition of rocks by chemical alteration (*always in the presence of water)
What does chemical weathering work along with and what enhances it?
Almost always works along with Physical Weathering!
Chemical Weathering is enhanced by increased temperature and rainfall
What is the most common form of weathering?
Chemical weathering, especially in the tropics
What are the 3 main types of chemical weathering?
A.Spheroidal weathering
B.Oxidation
C.Carbonation and Solution (Karst formation)
What is spheroidal weathering?
Spheroidal weathering of granite boulder—water dissolves cementing material in rocks…Results in rounded edges and corners
What is oxidation?
Oxygen combines with iron-bearing minerals to form rust. Oxidation gives many clays their orange/red color. The rust color outer surface is called a “Weathering Rind” (builds up through time)
What is carbonation and solution?
weathering by solution in water, rainwater and groundwater attacks and dissolves rock
What is limestone especially susceptible to?
Chemical weathering. This is due to the fact that it is composed of calcite, which is easily dissolved by water
What is Karst Topography?
Topography created by surface and subsurface dissolution of limestone
What kind of rock is limestone?
a sedimentary rock composed largely of calcium carbonate. (Limestone is one of the most abundant sedimentary rocks in the world). Limestone is formed over millions of years from the accumulated skeletons of sea dwelling creatures such as mollusks and corals
What are the major Karst Regions of the World?
Some major karst regions: SE China; Yucatan, Mexico; Cuba, Puerto Rico; and US: Kentucky, Indiana, Florida, Appalachians
What are the necessary conditions for Karst formation?
- High CaCO3 (Calcium carbonate) rocks
- Usually humid climates (at the time of formation)
- Acidic water present- acids supplied by vegetation cover, soils, acidic rainfall
- Joints in the bedrock
What are joints?
Bedrock must have complex joint structures to act as channels for water
What are some common features of karst landscapes?
- Caverns (caves) and related features
- Sinkholes
- Lack of surface water
- Disappearing streams
- Towers/“Haystack Hills”/mogotes
Look at slide 36 for picture
What are caverns?
Caverns are Solution Features
What are solution features?
water has dissolved much of the rock to leave a void
What are some examples of a solution feature?
Natural Bridge. Formerly part of an underground stream channel—cavern collapsed and only the arch remains.
Natural Tunnel, VA.
What are buggered rocks?
They are highly bent and broken from fault movement – which results in many small cracks for water to dissolve the rock away
what are depositional features?
stalactites, stalagmites, columns. Calcium carbonate precipitates out of the water
How do cave streams form?
Water dissolves the surface limestone causing streams that disappear into the ground
What are prominent “solution” features in karst areas?
Sinkholes
What are large areas of sinkholes called?
“Sinkhole Plains”
What is a tower karst?
Most mature landscape?
How do karst landscapes form?
slide 50
What are some common issues in karst regions that influence human activities
Common issues in karst regions that influence human activities include ground subsidence, sinkhole collapse, groundwater contamination, and unpredictable water supply.
How can sinkholes by induced?
Sinkholes can be induced by human land use, including removal of groundwater
What percent of the world’s population obtains its water from karst aquifers?
25%
Why are karst aquifers especially prone to pollution?
Water flowing from surface into karst aquifers through joints can bypass the filtering capability of soil and allow pollution. Sinkholes make perfect dumps.
