You are mapping a transgressive sequence that is dipping down slope steeper than the ground surface. Would you expect the limestone unit to be found upslope or downslope?

• A. Upslope
• B. Downslope
• C. Along strike
• D. At the top of the unit

Answer: (B)

The important idea here is how a dipping bed intersects the ground surface. If a bed tilts more steeply than the surface it sits on, the plane of that bed will intersect the surface downslope. In practice, a limestone bed that dips steeper than the ground surface will outcrop downslope from where the less-steep, overlying materials are seen. So, for this transgressive sequence, the limestone would be found downslope. If the bed dipped less steeply than the surface, it would outcrop upslope; if it dipped at the same angle, it would run roughly along the surface.