Million years ago Western Kansas was covered by a great inland sea. The sea left chalk behind, creating the great formations known as Monument Rocks, now a national park in Gove County. It also left vertebrate fossils, like sharks and fish. This huge inland sea had a powerful effect on the land to the west—and the dinosaurs living there. Member station KPR says the best place to see the chalk left over from this sea is at Monument Rocks, or at Castle Rock in eastern Gove County.