Clast

Clast A clast is a fragment of geological detritus, chunks and smaller grains of rock broken off other rocks by physical weathering. Clasts can range in size from microscopic particles to large boulders. The study of clasts is an important aspect of sedimentology, which is a branch of geology.

Formation

Clasts are formed through the process of weathering and erosion. Weathering is the breakdown of rocks at the Earth's surface, due to factors such as wind, water, and temperature changes. Erosion involves the movement of these weathered materials by natural forces such as water, wind, ice, or gravity.

Types of Clasts

Clasts are classified based on their size, composition, and the processes that transported them. The main types of clasts include:

• Gravel - Clasts larger than 2 mm in diameter.
• Sand - Clasts between 0.0625 mm and 2 mm in diameter.
• Silt - Clasts between 0.0039 mm and 0.0625 mm in diameter.
• Clay - Clasts smaller than 0.0039 mm in diameter.

Clastic Rocks

Clasts are the building blocks of clastic rocks, which are a type of sedimentary rock. Clastic rocks are formed by the lithification of clasts, which involves compaction and cementation. Common types of clastic rocks include:

• Conglomerate - Composed of rounded gravel-sized clasts.
• Breccia - Composed of angular gravel-sized clasts.
• Sandstone - Composed of sand-sized clasts.
• Shale - Composed of silt and clay-sized clasts.

Importance in Geology

The study of clasts and clastic rocks provides valuable information about the Earth's history. By analyzing the size, shape, and composition of clasts, geologists can infer the conditions under which the rocks were formed, the environment of deposition, and the geological history of the area.

Related Pages

• Sedimentology
• Weathering
• Erosion
• Sedimentary rock
• Conglomerate (geology)
• Breccia
• Sandstone
• Shale