The Natural Beauty of Erosion

Exfoliation on Half Dome

Erosion PowerPoint

The Story of the Grand Canyon

The Power of Water

Weathering is the breaking up of rocks by water, ice, chemicals, plants and changing temperature.  There are two types of weathering:

• physical or mechanical weathering
• chemical weathering

Physical or mechanical weathering breaks rocks into pieces. Ice is the major force in this type of weathering. Water fills the cracks of rocks naturally during rainstorms but if the temperature falls and causes the water to freeze it expands in the cracks and may push hard enough to split the rock. In a similar way, plants, especially trees,  may grow in the cracks of rocks sending there roots down deep into the cracks looking for water. As the roots grow the pressure can cause the rock to split.

Chemical Weathering caused by action of water. This type of weathering affects the minerals within the rocks. Rain, streams, and ocean water dissolves minerals from rocks, causing the rocks to crumble.

Weathering starts the process of erosion by breaking down rock. The main product of weathering is soil.

  Erosion and Deposition

Erosion is the process by which weathered rock and soil are moved  from one place to another. Erosion carves the Earth's surface creating canyons, gorges, and even beaches. There are five agents of erosion:

• gravity (constant pulling on all matter on Earth)
• running water (rivers and streams)
• wind
• glaciers
• waves

Deposition is the process by which sediments (small particles of rock) are laid down in new locations. Deposition builds new landforms. Usually water is responsible for deposition but landslides can be caused by earthquakes and volcanoes.

For more info on deposition see the above erosion links.