FIGURE 18. 1. Sharp, structurally conformable contact of Member Four (Th4) on Member Three (Th3). At this locality, the base of Member Four is a thick channelform sandstone that rests on greenish-brown clays and calcareous claystone of Member Three. 2. Close up of contact above showing convex-up dish structures in Member Three calcareous claystone beds. These structures are interpreted as dewatering structures probably associated with rapid burial by the Member Four channel sand. Rock hammer for scale.