Chapter 6 - Weathering Flashcards
When does mechanical weathering occur?
Mechanical weathering occurs when rocks are broken apart by physical force.
What is denudation?
Denudation is the wearing down of the surface of the earth. It is done by weathering and erosion.
What is freeze-thaw action
- Mechanical weathering
- Colder climates or high up in mountains
- Water collects in crack in the mountains
- Freezes at night and expands
- Rock breaks and falls to scree
What is exfoliation?
Exfoliation is an example of mechanical weathering in hot climates. The outer layer of rock heats during the day and expands. It contracts with the cold at night. Eventually the outer layer cracks.
What are the surface features of a karst landscape?
Surface rivers, swallow holes, dry valleys, limestone pavements with clints and grikes, bedding planes and joints e.g. The Burren, Clare
What are grikes?
Gaps between the blocks of a limestone pavement. Joints in the rock were opened wider when the limestone was dissolved by the rainwater thought the process carbonation.
What are clints?
The blocks of limestone that form a limestone pavement.
What are stalagmites?
Cone-shaped deposits of minerals on the floor. Water drops, evaporates and limestone is left behind. It builds up from the floor.
What are stalactites?
Come-shaped deposits of minerals from the roof. Water drops, evaporates and leaves limestone. Over time, they grow downwards.
What is weathering?
The breakdown of rock, usually but the forces of the weather. There is two types: chemical and mechanical
What is chemical weathering?
A chemical reaction between the rock and then acidic rainwater. Carbonation is a form of chemical weathering.
What is biological weathering?
Involves the actions of flora and fauna. Plant roots are effective at growing and expanding cracks in the rocks.
What is carbonation?
Happens when rain falls and takes carbon dioxide from the air. Acts like a weak acid which opens cracks and joints in the limestone by dissolving it.
