By: Mika 

Breaking down rocks by physical means 

Rocks weather in peeling off in sheets 

breaking down rock by chemical reactions 

Thawing and freezing of water in cracks of rocks 

rocks have been shaped by blowing wind and sand

Water breaks rock into pieces from tumbling the rocks 

rocks grind against each other and the rocks break into smaller pieces

the roots grow and become strong to the point where they can break rocks apart 

animals like worms can build huge tunnels and they do have a very postive effect on the world