The elongate sandstone body that crops out in Owen and Greene Counties consists of the Bethel and Sample Formations overlain by the Elwren Formation; limestone units which normally intervene are absent. The body is an abandoned distributary finger of the late Paleozoic Michigan River system, and is composed of a lower thin part, probably of tidal origin, and an upper, thicker part. Relationships of high permeability to crossbedding and low permeability to ripple-bedding define reservoir units. Permeability values of sandstones near the surface are much higher than those in the subsurface, the result of decementation by downward-flowing ground water. This suggests how permeability in a sandstone body buried below an unconformity might develop.