Bed (of rock) (7)
I believe the answer is:
stratum
(Other definitions for stratum that I've seen before include "stretch of rock" , "(Geological) layer" , "Layer (of rock)" , "rock band" , "Social class - level" .)
I believe the answer is:
stratum
(Other definitions for stratum that I've seen before include "stretch of rock" , "(Geological) layer" , "Layer (of rock)" , "rock band" , "Social class - level" .)