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

Notable Replies

  1. Big Obsidian Flow, at Newbury Caldera in central Oregon, USA. A frozen rive of black glass.

  2. I don't know how I read the headline as "Tell us about your beloved geocities," but I was all about to tell you about this beautiful 3-page geocities website I made in '97 where I proved conclusively that in an infinite universe, aliens had to exist. I think it even had spinning globe gifs, which really made it legit.

  3. Writing-On-Stone Provincial Park in Southern Alberta

  4. I also came here to talk about my favorite geocities page with midi files and blinking tags and lovely altcaps text.

  5. I'm a geologist DO NOT MAKE ME PICK JUST ONE!

    (So here are two)

    Channeled Scablands - Eastern WA,
    The most impressive thing for me is that Bretz theorized they were formed by floods without the benefit of aerial photography, and prior to the understanding of the Pleistocene glaciation as a source of the tremendous volume of water needed to create the landforms.

    The Great Unconformity within the Grand Canyon - The gap in time between the rock layer I'm sitting on and the layer to my back is on the order of one billion years.

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