The Western Interior Seaway is an ancient intracontinental seaway that occupied much of modern western North America and existed throughout much of the Cretaceous Period. This site discusses the physiography, origin, evolution and biologic significance of this intriguing geologic feature. Specific topics include sea level fluctuation, marine and non-marine life, and sedimentary rocks associated with the Western Interior Seaway. A paleogeographic map and discussion are provided with numerous links to additional information on related topics.
