Monument Rocks (also known as Monument Rocks Chalk Pyramids) are a series of large chalk formations in Gove County, Kansas, rich in fossils. The formations were the first landmark chosen by the US Department of the Interior as a National Natural Landmark. The chalk formations reach a height of up to 70 ft (21 m) and include formations such as buttes and arches. The carbonate deposits were laid down during the Cretaceous Period in what was then the Western Interior Seaway, which split the continent of North America into two landmasses. They are estimated to have been formed 80 million years ago.
The chalk was deposited during the Cretaceous Period of geologic history, about 80 million years ago, when the central interior of the U.S. was covered by water. The several hundred feet deep water contained single-celled animals that drifted to the sea floor for eons, creating a mucky ooze. This material was perfect for trapping and preserving the remains of animals that lived in that ocean, such as fish, turtles, sharks, swimming reptiles called mosasaurs and plesiosaurs, swimming birds, gliding reptiles called pterosaurs, as well as invertebrate animals such as giant clams. Today the chalk beds routinely give up these fossils.
Kansas, too, has badlands, but they don’t attract many visitors—From the Lakota mako (land) sica (bad), the term was first used to describe the whimsically eroded mixed-grass hill country of the Lakota homeland in South Dakota. Although the landscape of the Dakota is much more famous—however, one of the big attractions of these formations is that they are undeveloped. It almost feels like you have discovered them. You will most likely have the place to yourself.
Castle Rock is a large limestone pillar landmark in Gove County, Kansas. The formation and the nearby badlands are located in the Smoky Hills region of Kansas, which is approximately 11 miles south of I-70 near Quinter, Kansas.