Tell us about your beloved geosites

What are your favorite geosites — cool geologic formations, awe-inspiring landscapes of rock, related museum exhibits, or even buildings made from particularly fascinating stones?

The Geological Society of London is asking people to submit their favorite geosites in the UK and Ireland. You can get in on that challenge via Twitter, Facebook, or emailing the Society at But that got me thinking about geosites elsewhere. What would you nominate for a list of the best geosites in the world?

One of my favorites is definitely the Flint Hills, rolling limestone hills in central Kansas that are cut through with narrow, deep creek ravines and covered with tallgrass prairie.

You can see neat cutaways of the Flint Hills geology, where highway workers blasted through some of the hills to clear the path of I-70 between Topeka and Salina. Despite the lush look the prairie gives the hills, in reality there's not much dirt for growing anything here. Just layer upon layer of rock with a fuzz of grass on top, like a giant chia pet.

The Flint Hills are the remains of one of the times that Kansas was part of a shallow, inland sea — in this case, during the Permian, about 286 to 245 million years ago. All that limestone is made from the skeletons, shells, and other calcium-rich structures of oysters, coral, sea urchins, and more.

Image: Jim Minnerath / USFWS