Monument Rocks Key Hole Arch, Kansas Poster

"Monument Rocks Key Hole Arch, Kansas" by Catherine Sherman. Bright afternoon light pours through Key Hole Arch in Monument Rocks. These formations in Gove County, Kansas, are eroding rapidly. Monument Rocks (also Chalk Pyramids) are a series of large chalk formations in Gove County, Kansas. Wind and rain have greatly increased the size of the key hole opening in the soft chalk rock. This area was once covered in the vast Niobrara Sea. Composed of layers of ancient sea creatures, the soft rocks are all that remain of the 80-million-old sea, which extended from the present day Gulf of Mexico north through Canada. The Monument Rocks formation was 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. and include formations such as buttes and arches and are rich in fossils. They are estimated to have been formed 80 million years ago during the Cretaceous Period. The Cretaceous is defined as the period between 145.5 and 65.5 million years ago, the last period of the Mesozoic Era, following the Jurassic and ending with the extinction of the dinosaurs (except birds). On January 29, 2008, Monument Rocks and Castle Rock 31 miles to the east were jointly named as one of the 8 Wonders of Kansas. Monument Rocks plays an important role in the history of the Smoky Hill Valley area. The Butterfield Overland Dispatch trail used Monument Rocks as a landmark to guide travelers through the region. Also, Ft. Monument was established nearby to protect the trail. It has been a tourist destination for many years, and I continued the tradition by visiting the rocks a couple of times. The rocks are on private land, where cattle graze. The owners allow visitors, but remember to be respectful of the cattle and the delicate chalk formations.