Is the river wharfe in mature stage?

Amazon River is 11 million years old already and its not too wide and releases 300 000 cubic centimeter per second so it is a mature river base to its characteristics.. :-)

It's been there for thousands of years.

A mature river is on a shallower slope and it doesn't have rapids or waterfalls. (Waterfalls: steep fall of water, as of a stream, from a height. Rapids: part of a river where the current is swift.)

Is a river with a gradient that is less steep than those of youthful rivers and flows more slowly. It is fed by many tributaries and has more discharge than a youthful river and its channels erode...

middle course, upper course, lower course...