ANTECEDENCE and SUPERIMPOSITION

"Drainage older that uplift or most recent exposure of the bedrock high"

  A set of diagrams below that illustrate both the antecedence and superimposition mechanisms.  In both cases, the drainage must predate uplift or most recent exposure of the bedrock high.  This is NOT evidence you find in the field.  But if the other criteria or evidence indicate the drainage predates uplift or most recent exposure of the bedrock high, the only two possible mechanisms are antecedence and superimposition.