Many rivers may seem as old as the hills, but they have their own life cycle, like many other natural features. Many trees grow, many trees sooner or later wither. But some rivers live longer than others. The portal livescience.com talked about the oldest river on Earth.
Surprisingly, the oldest river on the planet is even older than dinosaurs. Australia's Finke River, or Larapinta as it is called in the native Arantha language, appeared 300-400 million years ago.
The network of streams and canals stretches more than 640 km across the Northern and Southern Territory. Dry conditions in the center of the continent create cyclical flows; For most of the year, it exists as isolated bodies of water. But a combination of geological records, weather records and radionuclide analysis of surrounding sedimentary rocks has allowed scientists to date this river system to the Devonian period (419-359 million) or the Carboniferous period (359-299 million).
One of the most convincing evidence of Finke's impressive age is a geological anomaly known as crossflow. Instead of flowing parallel to load-bearing rock structures such as quartz, it flows through these solid mineral formations, traversing the MacDonnell Ranges of central Australia.
Flowing water always follows the path of least resistance, making horizontal flow look strange. Additionally, the presence and origin of this drainage system reveal important details about Finke's history. There is reason to believe that the river formerly had another mouth during the period when the ridge was first formed. That is, the river flowed through the area before the mountains appeared – the convex crust cut off the flow then.
The MacDonnell Ranges formed as part of the Alice Springs Orogeny; The tectonic process took place 300-400 million years ago. So it's reasonable to assume that Finke is at least no younger than these mountains.
Other evidence comes from erosion and weathering, both of which produce characteristic chemical properties. From there, you can understand where and how the surface interacted with the atmosphere and flowing water in the past. By using the radioactive signature of certain isotopes, scientists can also determine the age of these rocks because these isotopes decay at a fixed rate.
However, rivers are always moving. Some grow larger from year to year, others dry out completely. But what has helped Finke survive for so long?
Rivers can disappear if a sudden influx of sediment floods them (for example, from a volcanic eruption) or if the topography of the area changes so much that the water flows along a different path. Additionally, rivers may dry up due to global warming and/or human consumption of water.
Finke was lucky – Australia has had an unusually stable landscape for a very long time. This continent is located right in the middle of the Australian tectonic plate so there has been virtually no major tectonic activity in the past hundreds of millions of years. As a result, the Finke River system grew and expanded virtually unhindered for most of its history.
It is true that it is difficult to predict how long the river will last. History shows that old rivers may continue to flow as before, but many rivers in dry regions are changing due to human consumption. And this consumption will only increase as climate change makes dry regions even more arid.
