1. adj. [Geology]
Describes a bed that maintains its original thickness during deformation. Often pertains to relatively brittle, solid strata that deform by faulting, fracturing or folding, rather than flowing under stress. Incompetent beds are more ductile and tend to flow under stress, so their bed thickness changes more readily during deformation.
See: bed thickness, disharmonic, fault, fold, fracture, harmonic, stratum