1
Lichens grow on rock and release chemicals in their roots to break down the rock.
2
rain, sleet, or snow with a high acid concentration causes bonds to weaken
3
Rocks fall onto one another because of gravity and they break into smaller pieces
4
Water carries rocks and pebbles along the bottom of flowing water causing the rocks to weather and smooth
5
Wind blows sediment and other particles against rocks causing the rocks to wear away
6
Oxygen reacts with an element. It can form rust
7
Breaking down of rock by a physical force
8
Breaking down of rock through chemical changes
9
Tree roots grow in cracks in rocks and cause it to crack
10
Breaking of bonds that hold rock together and soften rock
11
water freezes in rocks, expands and causes the rock to break
