Kansas

Kansas Geological Survey FAQs 13. Are there caves in Kansas? According to the Kansas Speleological Society, the Kansas landscape is dotted with several hundred caves. Few layers of rock in the state are thick enough to support extensive cave systems, but caves are found in the limestone of the Ozark Plateau area in southeastern Kansas, the limestone of the Flint Hills, and in the gypsum layers of the Red Hills. Some of the Flint Hills caves are several thousand feet in extent. Nearly all are on private property. For more information, see the Survey publication Caves in Kansas, Educational Series 9. (This explains why even google had no hits on caves for Kansas. They gave only Kansas City info and repeated sites that are not at all related.)

Lakes & Reservoirs in Kansas, that's the USGS site. And the Wikipedia page list of Lakes, Reservoirs and dams.

Waterfalls - MichelesWorld page and the Flickr page and Kansas Travels Waterfalls Page Wow, these are extraordinary ! (there's even a bridge in one of the photos.)

Of Caves and Waterfalls, the VisitUSA page This is very brief and vague history and description. Appears that both of the mentioned "caves" were man-made. The work is poorly written and most difficult to read. There are no photos of anything.

Bridges by Bridge Hunter and there are a lot of them. Awesome indeed. Also find the Wikipedia page which has some more bridges, even some railroad bridges.

Natural Arches and Bridges in Kansas: The Eye of the Needle is located in Monument Rocks National Natural Landmark, also known as the Kansas Pyramids, south of Oakley, Kansas. The formations are made of sedimentary chalk (remains of ancient marine life) from a sea that once covered the state.

More about the Monument Rocks with wonderful photos of even more rock formations. Also see the Wikipedia page for National Natural Landmarks. Check out that Rock City.