Lecture 26 (Friday, March 29): Caves and Karst
Brief outline of this lecture:
Basics of Karst
Evolution of caves
Stalagmites and stalactites
Main points of this lecture:
Karst and caves form in soluble bedrock, usually limestone, and usually in wet climates.
Karst landscapes often lack surface water because water drains into underlying caves and channels.
Sinkholes are depressions of the earth surface resulting from collapse into underlying solution cavities.
Many, and perhaps most, sinkholes form as the result of groundwater withdrawal.
Stalactites are commonly pointed, whereas stalagmites are commonly round-topped.
Stalagmites and stalactites usually form as the result of degassing of CO2 from drip waters in caves.
Layered stalagmites can serve as records of past rainfall and climate change.
Caves are rarely more than hundreds of thousands of years old because they are eroded.
Figures used in this lecture:
Introduction to Karst
Causes of Sinkholes
Formation of Caves
Stalactites and stalagmites
How stalactites and stalagmites form
Fates of Caves
Reading assignment: pp. 233-235.
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