List of rivers by age

This is a selected list of the oldest rivers on Earth for which there is knowledge about their existence in past times.

The age of a river is difficult to determine. Generally, the age is estimated based primarily upon the age of any mountains it dissects; the age of the sea or ocean to which it eventually outflows can be irrelevant; for example, several rivers of the east side of the Appalachian Mountains are older than the existence of the Atlantic Ocean, which did not exist 130 million years ago. If a river fully dissects a mountain range, then this generally indicates that the river existed at least at the time that the mountain range rose.

...
Wikipedia