In geology, a bed is a layer of sedimentary rock greater than 1 centimeter (0.4 inch) in thickness, representing a single episode of sediment deposition. The original sediment of a bed is usually deposited in a horizontal sheet.

 

A bedding plane is the upper or lower surface of a bed. The lower surface is known as the sole of the bed.

 

Bedrock is solid rock that occurs below the soil and any regolith (rock fragments). It is the C or D horizon in a soil profile. On hillsides the bedrock may be only a few centimeters below the surface, whereas on prairies and plains it may be several meters down.