Western Interior Seaway

Prehistoric inland sea that split the continent of North America

The Western Interior Seaway was a large inland sea that split the continent of North America into two landmasses for 34 million years. The ancient sea, which existed from the early Late Cretaceous to the earliest Paleocene, connected the Gulf of Mexico to the Arctic Ocean. The two land masses it created were Laramidia to the west and Appalachia to the east. At its largest extent, it was 2,500 feet (760 m) deep, 600 miles (970 km) wide and over 2,000 miles (3,200 km) long.

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