How old are rivers?
It depends on the river, and the answer is usually much younger than you would guess. Two of the pages below give one river an age from a source; the third asks which river is oldest of all, and finds its sources disagreeing in public.
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Three rivers, three kinds of answer
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What the three have in common
Each one is a page about putting a date on a river, and each keeps its source beside the date. Where the sources disagree, the page shows the disagreement instead of picking a side for you.
The Colorado and the Mississippi pages each put their river next to the dinosaurs, and both rivers come out far younger. That is the useful surprise, and it is worth checking before you picture a dinosaur drinking from either one.
The oldest-river page does something different: it shows one organisation’s own pages disagreeing with each other, quoted word for word. It also warns that the rock is not the river, so a date for the rock a river cuts through is not a date for the river.
Where next
The rivers dinosaurs really did drink from have no names, and the page that explains why is What rivers did dinosaurs drink from? For the water running in all of these rivers, and how long it has been going round, read How has Earth’s water changed through time?