The Western Interior Seaway formed about 100 million years ago when the mountains that now define western North America lifted up as a result of tectonic forces. Those same forces flexed the land east ...

Long before the Great Lakes came to define the heart of North America, a much larger lake once ruled the land. Lake Agassiz, a prehistoric inland sea, spread across the continent with a reach that ...

Some people consider the Great Plains of America to be "flyover country." The truth of that pejorative falls outside the realm of science. It is true, however, that 80 million years ago one could not ...