Weathering And Erosion Flashcards
What is weathering?
The mechanical and chemical breakdown of rocks.
What is erosion?
Erosion is the removal of sediments.
What is physical/mechanical weathering?
Physical/mechanical weathering is where rocks are broken down into smaller pieces.
What is chemical weathering?
Chemical weathering is rocks are broken down by changing their chemical composition.
What are the three types of physical/mechanical weathering?
1) Freeze thaw weathering
2) Biological weathering
3) Exfoliation weathering
How does freeze thaw weathering occur?
Water seeps into cracks in a rock, overnight the water might freeze, if it freezes this will put pressure on the rock. Eventually the rock cracks even more and overtime the rock will break into smaller pieces.
What landscape feature is caused by freeze thaw weathering?
Talus. This is where large piles of broken rock fragments accumulate and the bottom of a mountain slope. This happens for example in New Zealand’s southern alps.
How does biological weathering occur?
A seed may be caught in a crack in a rock or a plant may grow near a rock and as it grows, it’s roots may act as wedges and put pressure on the rock. As the plant grows it will put more and more pressure on the rock. Overtime pieces of the rock may break off as a result of this pressure.
Where does freeze thaw weathering occur?
Typically in high altitudes prone to temperature fluctuations.
Where is biological weathering found?
Where rocks are exposed and the soil is shallow with an abundance of plant life.
How does exfoliation weathering occur?
Rock is heated up during the day causing it to expand. At night the rock cools and shrinks. This stretches and weakens the crust of the rock. Overtime the outer layers of the rock may peel off. This typically occurs in dark and igneous rocks.
What are the three types of chemical weathering?
1) Carbonation
2) Oxidation
3) Hydrolysis
How does carbonation occur?
Rainwater mixes with carbon dioxide forming a weak acid. When this comes into contact with calcium carbonate (limestone) the limestone is slowly dissolved.
How does oxidation occur?
Certain minerals react with oxygen. This forms oxides. Because of this rocks can get weaker and decompose. Eg. Rocks rusting. This happens at Badlands National Park USA.
How does hydrolysis occur?
Hydrolysis is where some minerals react with the molecules in water and leave their rocks to join these molecules in the water. It is the chemical breakdown of a compound due to reaction with water.
