The Finke River in Australia, known as Larapinta in the Indigenous Arrernte language, has been identified as the oldest known existing river in the world, estimated to be between 300 million and 400 million years old. This network of streams and channels spans over 400 miles (640 kilometers) across Australia's Northern Territory and South Australia. Due to arid conditions, the river flows intermittently, often appearing as isolated water holes for much of the year.
Dating and Evidence
Scientists dated the river system to the Devonian (419 million to 359 million years ago) or Carboniferous (359 million to 299 million years ago) period. This dating was achieved using geological records, weathering profiles, and radionuclide measurements from surrounding sediments and rocks. A significant piece of evidence is the river's cross-axial drainage, where it cuts across resistant rock structures, such as quartzite, within the MacDonnell Ranges.
Victor Baker, a geomorphologist at the University of Arizona, explained that this phenomenon, termed antecedence, indicates the river existed before the mountains formed. As the Earth's crust uplifted to create the MacDonnell Ranges (Tjoritja), the river continued to erode its path downwards. The MacDonnell Ranges formed during the Alice Springs Orogeny, an event 300 million to 400 million years ago, aligning with the Finke River's estimated age. Additional evidence is derived from erosion and weathering patterns, which, combined with radioactive isotope signatures, provide a timeline for the river's historical evolution.
Factors for Longevity
The Finke River's extended existence is attributed to Australia's long-standing tectonic stability. Situated in the middle of the Australian Plate, the continent has experienced minimal significant tectonic activity for several hundred million years. This stability, along with a lack of widespread glaciation during the Pleistocene epoch (2.6 million to 11,700 years ago), has allowed the river system to develop and persist with minimal interruption.
Future Outlook
Despite its ancient history, the Finke River faces future challenges. Ellen Wohl, a geologist at Colorado State University, noted that rivers in dry regions, such as the Finke, are increasingly impacted by human consumptive water use. This issue is expected to escalate as global water consumption rises and climate change causes many dry regions to become even drier. Should the Finke River eventually cease to flow, the New River, approximately 300 million years old and flowing through Virginia, West Virginia, and North Carolina, would be considered the next oldest existing river.