Types of Weathering _Approaching – 02

Earth’s rocky crust is mostly covered by a layer of sediment. Where did all these sediments come from? To answer this question, you will need to learn about weathering.

Weathering is any process that breaks rocks into smaller pieces. These smaller pieces are called sediments. The size of sediments can vary. They can be large boulders. They can just as easily be as small as tiny particles of clay.

The weathering of rocks are how sediments are formed. There are two basic types of weathering. One form of weathering is called mechanical. The other is called chemical weathering. Mechanical weathering involves motion. It is the motion that breaks up rocks. This action does not change the rock’s chemistry. Types of mechanical weathering are ice wedging and abrasion.

Ice wedging is caused by the freezing of water. The water seeps into cracks in rocks and freezes. When liquid water turns into ice, it expands. This increase in size pushes against the cracks in the rocks. This causes a larger crack to form. Every time a crack forms, water can seep more deeply into the rock. With every freeze event, the rock is broken up into smaller pieces. Potholes in roadways are evidence of ice wedging. They are very common in the northern states.

Abrasion occurs when rocks are struck by other materials. This material might include other rocks. For example, gravity may cause them to roll down a hill.  Abrasion may also involve the motion of water. Small stones can be carried along in a fast-moving stream. As they are being moved by the water they scrape against other stones.

Wind can also cause abrasion. Small sediments can be carried by the wind. This windblown sediment can break down existing rocks. In all cases, abrasion, causes rocks to be broken apart or worn down. With every strike, rocks are broken down into smaller and smaller pieces.