Lake Tai
Scientific studies suggest that Lake Tai's circular structure is the result of a meteor impact based on the discovery of shatter cones, shock-metamorphosed quartz, microtektites, and shock-metamorphic unloading fractures. The prospective impact crater has been dated to be greater than 70 million years old and possibly from the late Devonian Period. However, new research suggests that present evidence shows no impact crater structure or shock-mineral at Lake Tai. Fossils indicate that Lake Tai was dry land until the ingression of the East China Sea during the Holocene epoch. The growing deltas of the Yangtze and Qiantang rivers eventually sealed off Lake Tai from the sea, and the influx of fresh water from rivers and rains turned it into a freshwater lake.