The geologic wonderland of City of Rocks National Reserve in southern Idaho

The geologic wonderland of City of Rocks National Reserve in southern Idaho

Learn about the fascinating geologic landscape of City of Rocks National Reserve in southern Idaho with geology professor Shawn Willsey. Here he explains how the scenic fins, spires, and other bizarre rock shapes were formed from the 28-million-year-old granite that underlies much of the area.

You can learn more about southern Idaho geology by purchasing Geology Underfoot in Southern Idaho and Roadside Geology of Idaho. Both available locally or on Amazon.

I love doing these videos and will continue to do so but if you want to provide support or much appreciated gas money, you can send support via:

Venmo @Shawn-Willsey (be sure to put two L’s in last name)
or PayPal: https://www.paypal.com/donate/?hosted…
or a good ol’ fashioned check to this address:
Shawn Willsey
College of Southern Idaho
315 Falls Avenue
Twin Falls, ID 83303

34 Comments

  1. Gretchen L'Hommedieu on August 10, 2023 at 11:56 am

    Thank you for teaching the geology of this area. Very interesting.

  2. Green Man on August 10, 2023 at 11:57 am

    Image being people living around there before modern plumbing of fresh water to everyone’s home. It’s a desert area. Finally…some rain! But….the rain is SALTY.
    Talk about unfair!
    It had NEVER occurred to me that rain could be salty. I had always just assumed that it would be fresh.

  3. Discipleship etc — Josh Hunt. on August 10, 2023 at 12:05 pm

    Another good one!

  4. Charlie Watts on August 10, 2023 at 12:05 pm

    Shawn at 5:46 in the video it looks like some sort of dike or intrusion running through the rock.

  5. SystemicByDesign on August 10, 2023 at 12:06 pm

    https://youtu.be/gw-M3_1RWNU these 2 guys believe they’ve discovered megalithic construction in Wyoming. I’ve tried to explain that’s not the case but they’re dead set and determined lol

  6. john delong on August 10, 2023 at 12:07 pm

    At least a bazillion years ago I estimate.

  7. Arjun “Das” Prabudas on August 10, 2023 at 12:08 pm

    Commercial boots look like cheap sht to me.

  8. muzikhed on August 10, 2023 at 12:09 pm

    Excellent. I found it a really interesting talk, I like the explanations with detail on weathering and so on.

  9. David Leadford on August 10, 2023 at 12:21 pm

    Don’t think I’d be sticking my hand in those holes being in an area where there are rattlesnakes.

  10. Cary Grant on August 10, 2023 at 12:21 pm

    Is this granite part of the Idaho Batholith history which would be older than 28 MYA. If not, then what was the source of the granite, Yellowstone Hot Spot? I was intrigued by Professor Zertner’s crazy Eocene series and from what I have learned is granite implies there was volcanism above the area. 28 million years seem quick to erode overlaying volcanoes.

  11. Marsha Rose on August 10, 2023 at 12:22 pm

    Really appreciate your explanations and videos!

  12. David K on August 10, 2023 at 12:23 pm

    Thanks for this. I grew up in SW Idaho and have never made it to the City of Rocks. My son has climbed there many times from SLC.

  13. brent weissert on August 10, 2023 at 12:27 pm

    question: at 5:45 there appears in the background a strange discontinuity in the rock just behind you at a nearly vertical angle. It looks to be perhaps 2 inches wide. what is that?

  14. Sean O’Neill on August 10, 2023 at 12:28 pm

    I see you walked past what looks like a dike at 5:46. When did magmatic intrusions occur following the crystallization of this regions granitic batholith?

  15. Russ on August 10, 2023 at 12:30 pm

    City of Rocks, never heard of it, awesome spot.

  16. Eric Johnson on August 10, 2023 at 12:31 pm

    Alluvial shaped by A massive flood .

  17. Kevin Dorland on August 10, 2023 at 12:31 pm

    Apologize if I missed it… Is there a rough time frame of the granitic formations, you’re referring to, have been exposed to the surface? Deeply admire your work. TY.

  18. Quinton Ritz on August 10, 2023 at 12:37 pm

    used to have our easter picnics there. There is a formation that I have been told is called the elephants head. My Uncle and I would rock clime that.

  19. Kristy B on August 10, 2023 at 12:38 pm

    What a pretty place! Would love to visit and explore now…

  20. Keith Walker on August 10, 2023 at 12:38 pm

    These videos are so very interesting …… thank you

  21. Anne5440 on August 10, 2023 at 12:38 pm

    My favorite color of granite. Very much the same color as the granite in Central Washington and North. My copy of Geology underfoot arrived toady. Now that I’ve watched this I have the chapter in your book on City of Rocks. I’m trusting the donation I made has reached you by now. I’m off to learn some more now.

  22. Gary B on August 10, 2023 at 12:39 pm

    I’d have a hard time not putting my tongue to that rock to see just how salty it is…

  23. Tidget 77 on August 10, 2023 at 12:40 pm

    Great video! Thank you!

  24. kf1000 on August 10, 2023 at 12:42 pm

    went there more than 50 years ago

  25. Jay Anderson on August 10, 2023 at 12:45 pm

    Thanks for taking the time to make this and educate us. I learned a lot. It is a wonderful place to be!

  26. Toughen Up, Fluffy on August 10, 2023 at 12:45 pm

    Thanks for explaining why the granite is so friable. Being from Colorado, I’ve been in contact with many granite facies, but I haven’t been in contact with one so crumbly as what you’re describing. Amazing how the haline content of the rain can make such a difference between hard and crumbly.

  27. David Savage on August 10, 2023 at 12:47 pm

    That looks just like where my mom lives above Palmdale, in the San Gabriels in southern CA. You can see the Devil’s Punchbowl formation right out their front window. It’s beautiful, aside from the name.

  28. Dan Nelson on August 10, 2023 at 12:48 pm

    Exfoliation=choss

  29. Caldubs21 on August 10, 2023 at 12:48 pm

    i love you so much

  30. Roger Cotman on August 10, 2023 at 12:50 pm

    Great learning Video ………………… thanks …………..

  31. Misty on August 10, 2023 at 12:51 pm

    🙏 thank you 🙂

  32. Mountain Fisher on August 10, 2023 at 12:51 pm

    Ever see the unusual City of Rocks State Park in New Mexico? Really odd spires of volcanic tuff just popping out of the ground in the middle of a plain between Deming and Silver City.
    It isn’t a very large area, maybe about a square mile, your video reminded me of it.

  33. Tara Atzlan on August 10, 2023 at 12:53 pm

    It’s amazing how you can lie with such a straight face. You white guys do everything you can to hide the truth , the truth about what those rocks really are. Get your ass back to your caves in Europe

  34. Claude Glover on August 10, 2023 at 12:53 pm

    Reminds me of some areas in southern Arizona.

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