Western Interior Seaway
large inland sea during the mid- to late Cretaceous and the very early Paleogene; split North America into Laramidia and Appalachia; stretched from the Gulf of Mexico to the Arctic Ocean; at its largest, it was 760 m deep, 970 km wide, 3200 km long / From Wikipedia, the free encyclopedia
The Western Interior Seaway [1] was a huge inland sea. It split North America into two halves for most of the mid- and late-Cretaceous Period. It was up to 2,500 feet (760 m) deep, 600 miles (970 km) wide and over 2,000 miles (3,200 km) long.