Physical (mechanical) weathering

Physical weathering is also known as mechanical weathering. This type of weathering occurs when rocks and other landforms are broken down by physical factors in the environment. These physical factors include wind, water, sun, ice and temperature changes. This type of weathering does not change the chemical composition of the rock or minerals. An example would be waves crashing against a rocky shoreline, slowly breaking apart the rocks into smaller pieces.

Types of physical weathering

There are various ways that physical weathering can take place. We explore some of the most common forms of physical weathering.

Frost wedging, or freeze-thaw weathering usually occurs in temperate humid climates. Water enters into the cracks within a rock. During the night, temperatures drop and the water freezes. When water freezes it expands, putting pressure on the rock. During the day, the temperatures rise and the water melts. This cycle will eventually put enough pressure on the rock to cause pieces to break off.

Thermal expansion or insolation weathering usually occurs in arid regions. During the day, temperatures rise, heating the rocks and ground. As they heat up, expansion occurs. During the night, temperatures drop and the rocks and land lose their heat. This causes contraction. This cycle will cause cracks in the top layers of soil, rocks and landforms. Eventually, surface pieces will peel away in a process called exfoliation.

Biological weathering occurs when something living interacts with the weathering processes, causing the rock to break down. Biological weathering can be considered a type of physical weathering. Sometimes biological weathering is referred to as