Although it is difficult, it is nonetheless possible to determine the age of a river. The oldest river present on Earth is in Australia and dates from the Paleozoic. Its age would be between 350 and 400 million years.
After years of debates, the Amazon river was declared the longest river in the world with 6,992.06 kilometers. However, the oldest river we have on Earth is much shorter. The Finke River in central Australia (Alice Springs area) is only 600 kilometers long!
This river would be between 350 and 400 million years old. Since the latter draws characteristic of flat-land rivers, scientists have thus concluded that it precedes the formation of the mountains present in the zone and the formation of these same mountains is dated between 300 and 400 million years ago.
It should be noted that the age of a river is usually determined by the age of the mountains that it crosses and this is the case for the Finke River. However, this method is not always reliable since the course of the river or even the direction of its flow may change over time, as is the case of the Amazon.
For this reason, Science sometimes uses carbon-14 dating of fluvial sediments. Thus, it turns out that the age of the deepest sedimentary deposit determines the age of the river itself, although it will be an approximation. Indeed, some rivers can dig their beds in deeper sediments. In addition, beyond carbon-14 dating, researchers can also use optically stimulated luminescence (LSO).
The second river considered the oldest on Earth is the French Meuse, cutting the Ardennes massif. The Meuse was formed between 320 and 340 million years!