The Great Unconformity near Cody, WY: over 2 billion years of geologic time on one surface!

You can support my field videos by going here. Thanks! www.paypal.com/donate/?hosted_button_id=EWUSLG3GBS… Also, I apologize for mispronouncing "Shoshone" and "Absaroka". I have been properly corrected by several of you. Thank you. To be fair, I live near the iconic "Shoshone Falls" in southern Idaho where it is locally pronounced "show shown" not "Show show knee".

Thanks for the memories! When I was a student at Cody high school in 1952 I peeled back a bit of Flathead Formation to reveal a granite surface that looked almost polished. That made me wonder if glaciation had been involved at some time. (Back then the granite was just termed "Precambrian.") A nearby red granite yielded a 20mm magnetite crystal for my collection.

I have a new appreciation for the scenery on road-trips after your videos

Geology is so cool. Just put your hand across a couple billion year gap in the geologic record, nbd. But what's more important to me, at least, is to be able to decipher the rock and then to be able to tell that story to others. Thanks Shawn. This is what the study of geology is all about. So cool.

Touching something that's over 2 billion years old could be such a spiritual and humbling experience. That would be something like 40 million human generations before our present time.

Your excellent video brought back memories of exploring the 900 million years (myr) Ozark Dome Great Unconformity in a road cut through just west of my hometown of Fredericktown, Missouri. The beginnings of the ~520 myr old Lamotte Sandstone lap up gently against the base of the same re-exposed rhyolite hills that survived the continental and perhaps global Cryogenian ice age of 850 and 635 myr ago. At the base of these hills, you can pick up water-rounded rhyolite pieces of the hills that, by their locations, likely date back to the earliest start of the open-air weathering of the hills. These transitional stones -- igneous stones at the first and roughest stage of becoming sedimentary deposits -- are so weathered you can peel them apart with your bare hands in onion-like layers, despite them being composed of the same granite-hard rhyolite in the hills themselves. The length of open-air and shallow-water weathering required to soften the interior of hand-size and larger rhyolite stones boggles the mind. It must have been a very boring place for a very long time indeed. Looking to the west from the top of that same hill, you can see other small rhyolite hills poking up in the distance. It is a vision of the time shortly after the melting of the glaciers when shallow oceans filled gaps between the hills, and the hills formed an archipelago of islands. It is, quite literally, a fossil landscape of an era nearly a billion and a half years in the past, from a time when no land plants or animals disturbed the immense views of rock, ice, water, and sky.

Nice! Been there many times with students during field camp trips to WY. Those Cambrian SS show nice onlapping features over by the power plant exposure. There's also that little channel scour in the basement right where you were, which I interpret as a stream channel flowing to the ocean before the beach sands arrived. I think there's a bit of fluivial layering within it, but hard to say for sure.

Cody is an exceptionally beautiful area. I'd like to see something covering the Yampa river valley through Dinosaur National Park if you ever get down that way.

This is absolutely mind-blowing! And I thought that we had some pretty old rocks here in the UK. This has been a really fascinating video and to see the Great Unconfirmity so clearly defined, just incredible.

In Western Colorado the Great Unconformity is composed of gneisses and schists with granitic intrusions. The metamorphic gneisses are ~1.8 billion years old and the granitic intrusions are ~1.4 billion years old. They are covered by the Triassic Chinle Formation, which is ~215 million years old, with over 1.2 billion years of missing time between them.

I was in Cody this summer for a seasonal job! The landscape is so fascinating from a geologic perspective. The leading theory on how Heart Mountain was formed is mind blowing!!

Awesome job,I'm fortunate enough to work with all of these beautiful rocks. It's really interesting to learn more about them from a Professor. Keep up the great work.

There is a place along the Merced River (which flows out of Yosemite) a ways upstream from the town of Mariposa where the granite which makes up most of the Sierra Nevada Mountain Range has been eroded deeply enough to expose older folded and eroded sedimentary rocks.

Enjoyed seeing this, Shawn, thank you! Another highly accessible spot to see this unconformity is along Highway 24, Manitou Springs, west of Colorado Springs. Garden of the Gods Park is just to the north, with beautiful hiking and some rock climbing. The iconic red sandstone of the Fountain Formation, Paleozoic sedimentary rocks, on top of Billion year old Pikes Peak Granite batholith.

There is a really nice visual of the great unconformity on Frenchman mountain in Las Vegas as well. It is on Owens road at a little road cut as you drive up to a new housing development. Worth a view.

Canyon walls and road cuts are fascinating windows into what lies beneath the soil we tread and drive over. Great content 👍

Cody, Wyoming, my home town. Never knew what was in my own back yard. Thank you!

"and just like that I walked across the great unconformity" wow what a humbling and surreal experience.

Great information, I am learning so much! Love your channel!

That is a majestic looking canyon. Awesome !