 Lake Zaysan, however, may be even older, dating possibly from the Cretaceous period with a likely age in excess of 65 million years old (most probably around 70 million years), although its exact age is controversial and labelled with some uncertainty.A direct indication of the Lake Zaysan's age is hard to find, although some geological studies of the Zaysan Basin have been reviewed.Artificial reservoirs cover large surrounding areas.Modern geological analysis of the entire field, apparently, supports an exceptionally old age for Lake Zaysan.