Topic summary
Subsurface

Extracted from the Wikipedia article Bedrock.
Weathering of bedrock
Exposed bedrock experiences weathering, which may be physical or chemical, and which alters the structure of the rock to leave it susceptible to erosion. Bedrock may also experience subsurface weathering at its upper boundary, forming saprolite. Rock fragments can disconnect from the underlying bedrock, where they are found within a weathering or soil profile asfloaters.