Great Lakes: A Postglacial Freshwater Newcomer Among Ancient Lakes

The Great Lakes formed in the last ~10,000 years, making them geologically very young compared with family of ancient lakes. Baikal is dated at over 25 million years old, Tanganyika around 5–6 million, and other basins like Caspian and Malawi extend back several million years, with Issyk-Kul around 3 million. Lake Zaysan has debated claims up to ~70 million years. The oldest-lake ranking depends on whether one dates the basin, sediments, or continuous lake conditions, but the takeaway is clear: the Great Lakes sit at the tail end of a long, ancient lake history.