Limestone Flashcards
1
Q
How are limestone pavements formed? (3 steps)
A
- Limestone is made of blocks of rock, with bedding planes and joints.
- Limestone is permeable, so rainwater can percolate through it, dissolving the stone and enlarging the joints and bedding planes. This process is called chemical weathering.
- Enlarged cracks and joints are called grykes, and the upstanding blocks of rock are called clints. This blocky rock is a limestone pavement.
2
Q
How are swallow holes formed? (2 steps)
A
- When a stream flows over an area of limestone they can dissolve a much larger area.
- Joints can be enlarged so much that a hole develops, through which the stream can flow underground.
3
Q
How are caverns formed? (3 steps)
A
- After flowing through a swallow hole, water keeps sleeping along bedding planes and down joints until it reaches impermeable rock.
- When there are many joints and bedding planes close together, large areas of rock can be dissolved quickly.
- This large underground space is called a cavern.
4
Q
How are stalactites and stalagmites formed? (4 steps)
A
- Water flowing underground is dissolving limestone as it goes and is carrying it as solution.
- Water drips from the ceilings of caverns slowly and evaporates, depositing the calcium carbonate.
- This builds over time to form stalactites.
- Water dripping from the end of stalactites builds up on the floor upwards to form stalagmites.
5
Q
What is intermittent drainage? (2 points)
A
- When a stream disappears through a swallow hole, it travels through a series of caverns.
- It eventually reaches impermeable rock, and flows over it until it reaches the surface as a stream.
6
Q
How are scars and screes formed? (2 steps)
A
- Scar are exposed cliffs of limestone, where huge sheets of ice scraped away the soil.
- The exposed surface is affected by freeze-thaw action, where water enters the cracks, freezes and expands.
- Repeated freezing and thawing eventually breaks off rock, forming a scree slope at the bottom of the cliff.
