This is a pattern of drainage where rivers flow across the landscape without regard to the differences between soft and hard bands of rock.

The Susquehanna River could only cut through these ridges of the Appalachian mountains if it once flowed on a gently sloping landscape and has now cut down into a land with different kinds of rocks.

Antecedent drainage is common on most continents and it has played a major role in influencing the routes connecting cities.

The gaps that rivers seem to cut in mountains and upland ridges are often produced by antecedent rivers. Thus the gaps in the rim of the London Basin and the Paris Basin are antecedent rivers, as are those that cut in to the Appalachian mountains of North America.