Types of Weathering _Approaching – 03

Water can be a powerful force in weathering. Streams and rivers can move rocks and sediment. This motion causes them to collide into each other. This collision breaks rock into smaller pieces. Freezing water moves, or cracks, rocks apart. Water can also play another role in the weathering of rocks. There doesn’t even need to be motion involved.

Chemical weathering does not rely on motion. Instead, it relies on chemical reactions. These chemical reactions occur between two or more substances. Chemical weathering causes the chemistry of the rock to change. Water is the main cause of chemical weathering of rocks.

Water can cause many types of rocks to dissolve slowly over time. Water falls to earth in the form of rain. As it falls, it can pick up small amounts of certain gases. These gases mix with water to form weak acids. This acid rain is able to dissolve rocks. Water is not the only substance that can cause rocks to weather in this way. Oxygen too can cause chemical changes in rocks. If oxygen mixes with iron in rocks, the rock can become soft crumbly rust.

Our Earth is full of change. It’s hard to believe that small forces over a long time can create such change. Even the largest of rocks can be broken down by these forces. Both mechanical and chemical weathering are capable of causing great change. All sediment, from the soil in your yard to the sand on the beach came from rocks.