What is residual soil?

Residual soil is defined as soil that has formed in place from the weathering of underlying bedrock, which means it has not been transported from its source. This formation occurs when the bedrock weathers over long periods of time, breaking down into smaller particles that accumulate and develop characteristics influenced by the original rock material.

In contrast, soils developed on unconsolidated sediment are known as transported soils, as they originate from material that has been moved from its place of origin. The process of weathering rocks into smaller fragments refers to the physical and chemical processes that break down rocks but doesn’t specifically define what makes residual soil distinct. A pile of rocks at the base of a cliff is often referred to as talus and is associated with the physical movement of sediment, which again does not align with the definition of residual soil.