1. n. [Geology]
A layer of sediment or sedimentary rock, or stratum. A bed is the smallest stratigraphic unit, generally a centimeter or more in thickness. To be labeled a bed, the stratum must be distinguishable from adjacent beds.
See: bed thickness, competent, dipping bed, lamination, progradation, retrogradation, sediment, strike, superposition, true stratigraphic thickness, true vertical thickness