Physical Weathering
1. Change in temperature can break up rocks. When rocks are subjected to continuous hot and cold spells, they expand and shrink. Most rocks are made from mixtures of minerals.
These expand and shrink at different rates.
This causes stress to build up in rocks.
Eventually, they crack and crumble away. This is known as stratification.
To demonstrate this effect, we can heat a glass rod and drop it into cold
water. See animation below.
Physical
Weathering - mainly occurs in deserts and
high mountains
2. In regions where the temperature drops below 0°C , ice can weather rock away
When it rains, water collects into the cracks in rocks. If the temperature drops below freezing, it turns into ice and expands. The expansion effect of ice pushes the rocks apart. This is repeated as water thaws and freezes. Eventually the pieces of rock break off by fracturing or shattering and fall to the lowest point on the ground. This process is called Freeze thaw. The broken off pieces of rock are called Scree. |
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Test your understanding of mechanical weathering and the freeze-thaw process. 1. In physical weathering, what happens to the minerals that make up the rock? 2. By how much does the volume of water increase when it freezes into ice? 3. What name is given to the jagged rock fragments that collect at the bottom of a slope? 4. Why do temperature changes cause the outer layers of a rock to flake off? 5. Which process involves water entering a crack, freezing, and widening the gap?⛰️ Knowledge Check: Physical Weathering
Check Answers
2. Approximately 10% (Water expands when it turns to ice).
3. Scree (The term for weathered rock fragments at the base of a slope).
4. Expands when hot and contracts when cold (This repeated stress breaks the rock).
5. Freeze-thaw action (Also known as frost shattering).
Tags:Erosion, Weathering, Biological weathering, Freezing, How do weathering and erosion work together, what does weathering mean, chemical weathering acid rain,