Inland sea

For the sea in Japan, see Inland Sea

An inland sea is a shallow sea that covers central areas of continents during high stands of sea level that result in marine transgressions. In modern days continents stand high, eustatic sea levels are low, and there are few inland seas, none larger than the Caspian Sea. Modern examples might also include the Great Lakes, the recently (<10,000 ybp) reflooded Persian Gulf, and the South China Sea that presently covers the Sunda Shelf.

On a geologic time scale, inland seas have been greater in extent and more common.

A vast inland sea extended from the Gulf of Mexico deep into present-day Canada during the Cretaceous. See the Western Interior Seaway.

At the same time, much of the low plains of modern-day northern France and northern Germany were inundated by an inland sea, where the chalk was deposited that gave the Cretaceous Period its name.

The Amazon, originally emptying into the Pacific, as South America rifted from Africa, found its exit blocked by the rise of the Andes about 15 mya. A great inland sea developed, at times draining north through what is now Venezuela before finding its present eastward outlet into the South Atlantic. Gradually this inland sea became a vast freshwater lake and wetlands where sediment flattened its profiles and the marine inhabitants adapted to life in freshwater. Over 20 species of stingray, most closely related to those found in the Pacific Ocean, can be found today in the freshwaters of the Amazon, which is also home to a freshwater dolphin. In 2005 fossilized remains of a giant crocodilian, estimated to have been 46 ft (14m) in length, were discovered in the northern rainforest of Amazonian Peru [1].

In Australia the promise of an expected inland sea was one of the prime motives of inland exploration of Australia during the 1820s and 1830s. The main champions of the theory were Charles Sturt and John Oxley, but it had a number of other supporters. Notable sceptics included Edward John Eyre.