Chemical Weathering

Weathering

• What is weathering?– Weathering is the disintegration and

decomposition of rock at or near the surface of the earth.

Weathering

• Types of Weathering– Mechanical

• Physical disintegration of rock into smaller fragments, each with the same properties as the original.

– Chemical• Process by which the internal structure of a

mineral is altered by the addition or removal of elements.

• A chemical process CHANGES or ALTERS the composition of the rock during disintegration

Chemical Reactions

Characteristics of Chemical Reactions:

Bubbling

Foaming

Change in Temperature

Color Change

Factors that Effect Chemical Weathering

– Temperature• Chemical decomposition of rock will be faster in warmer

climates.

– Hardness• Rocks and minerals that are “soft” will weather faster than

those that are hard. Limestone is not as hard as granite.

– Time• Natural chemical weathering is a slow process. The longer a

rock has been exposed to chemical decomposition, the more likely it is to be weathered

Weathering and Soil Formation

• Mechanical and Chemical Weathering Promote Soil Formation

• Soils contain small pieces of rocks and minerals as well as organic material.

Soil Formation

Chemical Weathering by Acids

• Acids dissolve some of the minerals in rocks which promotes disintegration and weathering

• In our environment, chemical weathering can occur as a result from acid rain and acids produced by plant roots and plant decomposition.

Effects of Acid Rain