Bedrock

Bedrock is a very important part of the Earth. In geology, bedrock is the solid rock that is found deep under the surface. It lies beneath layers of soil, loose rocks, and other materials that are not as hard. This layer of solid rock is called the rockhead when you reach the top of it.

Bedrock helps to support everything above it, like buildings, roads, and even whole landscapes. It is made up of many different types of rock, such as granite, limestone, and sandstone. These rocks have been there for millions of years and form the strong base of our planet’s surface.

Studying bedrock helps scientists understand how the Earth was formed and how it changes over time. It also helps engineers and builders know where it is safe to construct things. Whether you are walking on grass, sand, or dirt, bedrock is always there, deep below, holding everything together.

Definition

Bedrock is the solid rock that lies underneath the looser material on the Earth's surface. When this solid rock is visible on the surface, it is called an outcrop. The broken and weathered rock, like soil and subsoil, that sits on top of the bedrock is known as regolith.

Engineering geology

In engineering geology, the top layer of solid rock under the soil is called rockhead. Finding this rockhead is very important for building projects. Engineers use digging, drilling, or special tools to locate it, especially when the rock is far below the surface, sometimes hundreds of meters deep.

Weathering of bedrock

Exposed bedrock goes through a process called weathering. This weathering can be physical or chemical, and it changes the rock's structure, making it more likely to break apart through erosion. Bedrock can also weather from below, creating a material called saprolite. Small pieces of rock can break off from the bedrock and end up in the soil above, known as floaters.

Geological map

A geological map shows what kinds of bedrock are in an area. It tells us what rock would be seen if all the soil or other loose material were taken away. If there is too much of this loose material to see the bedrock clearly, the map will show the loose material instead, such as alluvium.