Big rocks, small pieces
Three ways that nature breaks a mountain rock.
Heaps at the base
At the base of a mountain, you may see heaps of sand, soil and stones. They are called sediments.
Where did the sand, soil and stones come from?
What this lesson covers
The idea
Physical changes caused by temperature changes, growing tree roots and water freezing in cracks break large rocks into smaller pieces, forming sediments of sand, soil and stones.
Heaps at the base
At the base of a mountain, you may see heaps of sand, soil and stones. They are called sediments.
Where did the sand, soil and stones come from?
- Big rocks broke into smaller pieces
- Small pieces joined to make big rocks
- They have always been sand and stones
Break the rock
Pick a cause and watch what happens to the rock. Try all three.
Sediments
The pieces collect at the base of the mountain as heaps of sand, soil and stones. These are sediments.
Sediments are formed by physical changes that break up large rocks into smaller pieces.
- Cause | What happens to the rock | Kind of change
- Temperature changes due to climate | it breaks into smaller pieces | physical
- Growing roots of trees | it breaks into smaller pieces | physical
- Freezing of water within cracks | it breaks into smaller pieces | physical
Notes
Sediments are heaps of sand, soil and stones. They are formed by physical changes that break up large rocks into smaller pieces: temperature changes, growing roots of trees, and freezing of water within cracks.
Check yourself
What are heaps of sand, soil and stones at the base of a mountain called?
Sediments are formed by _ that break up large rocks into smaller pieces.
Temperature changes, growing roots of trees and freezing of water within cracks. How many of these can break a rock?
Answer: 3
Three: temperature changes, growing roots and freezing water in cracks can all break rocks.
Water gets into a crack in a rock and freezes there. What can happen to the rock?
- Tree roots. Roots are part of a tree. Heaps of sand, soil and stones are sediments.
- Cracks in rock. A crack is a gap in a rock. The heaps are called sediments.
- Sediments — correct. Yes! Sediments are formed when large rocks break into smaller pieces.
- physical changes — correct. Yes! The rock only breaks into smaller pieces.
- chemical changes. Here the rock only breaks into smaller pieces. That is a physical change.
- new substances forming. Breaking up a rock does not make a new substance.
- It must stay whole. Freezing of water within cracks can cause a rock to break.
- It can break — correct. Yes! Freezing of water in cracks can break rocks.
- It melts like ice. The rock does not melt. It can break.