External Forces that change the Earths Surface

1
External Forces that change the Earths Surface

• Zerrick Grant
• 1

2
External Forces

• Once land forms and other surface features have
  been formed by interior forces they are changed
  and sometimes destroyed by external forces.
• There are two categories of external forces that
  change the earths surface Weathering and
  Erosion.

3
Weathering

• The process by which rock is gradually broken
  down into smaller pieces
• Weathering can be Mechanical or Chemical

4
Mechanical Weathering

• The breaking up or physical weakening of rock by
  forces such as ice and plant roots
• Frost wedging is the most common type of
  mechanical weathering

5
Chemical Weathering

• The process by which the chemical composition of
  rock is changed
• Water and carbon dioxide are the most important
  forces in chemical weathering

6
Erosion

• Erosion is the movement of weathered materials
  including gravel,soil,and sand
• Water,wind and glaciers are the most common
  agents of erosion