Weathering is the breaking down of rock through mechanical and chemical means.

Mechanical weathering, also known as physical weathering, is when rocks are broken down by air, water, or living organisms.

Water can change the landscape by erosion and deposition.

Also by ice wedging.

Water flows into a crack where it sits and over night freezes. Because ice expands when frozen it deepens the crack in the rock. During the day it thaws and refreezes the next night. This process continues and the crack deepens until the rock splits.

Not only does water erode the landscape but so does air in a similar fashion.

Winds pick up bits of sand and rock which chip away at larger pieces of rock.

Roots can grow in the cracks of rock. While the tree grows it fills the cracks and forces the rock to break.

Chemical weathering occurs when particles in the rock react with other agents such as air creating rust or water and carbon dioxide creating carbonic acid.