SUPERIMPOSITION

"Transverse drainage gravels unconfined atop the bedrock high"

  A covermass that allows a drainage to cross a buried structure is the key criterion for accurately deciphering superimposed drainages.  Drainages sometimes cover bedrock structures in their gravel or alluvium, making their gravel the necessary covermass.  Willow Creek Canyon in the upper image exemplifies this criterion.  Gravels from the transverse drainage present in the foreground also outcrop atop the bedrock high in the distance.  In the lower image, transverse drainage gravel (white arrow) is preserved upstream of the bedrock high and acted as the covermass for transverse drainage incision (black arrow).