The Great Unconformity near Cody, WY: over 2 billion years of geologic time on one surface!
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- เผยแพร่เมื่อ 11 ต.ค. 2022
- One of the most mind blowing geologic features in western North America, the Great Unconformity represents over two billion years of time between the crystalline basement rocks below and the beach sands above. Team up with geology professor Shawn Willsey as he explores this fantastic unconformity and the rocks on either side near Buffalo Bill Reservoir just west of Cody, Wyoming in Shoshone River canyon.
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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".
Show-show-nee and ABS-roka.
@@toughenupfluffy7294 Yep. See my explanation above.
Don't apologize. All pronunciation is local.....you know, potaytoe, potahtoe. Screw 'em if offended. In Nevaaahda, we say Nuva (as in van) duh.
Many watching would question how you know the ages of the various rocks and say what's so great about an unconformity? Didn't any big change happen during the flood, after everything was made on the first or second day (I forget which)?
Fossils and radiometric dates would make good separate videos. Your photography is great.
Thanks for the show, and yeah, I'm a retired geologist.
@@kevinrussell1144 There was a long period of time between the events of Creation and the destructive/re-creative Great Flood. How long is the big question. The separation of land and water and spreading of land-based plants was on the third day.
According to your Bible and faith (you quote Genesis), free will allows you to believe in a strict (one day is ONE day) interpretation or you can go with the symbolic view for that first week. You also have to decide if enough time remains after Noah's era for all of human history to make sense (and for deciding what rocks formed after the flood and when it happened).
You can look it up. Noah's world-wide flood supposedly happened the same time (~2500 BC) the Great Pyramid was being built.
Several young earth creation sites also claim most of the rocks exposed in the Grand Canyon were deposited by THE Flood. Curiously, fossil assemblages from Grand Canyon limestones are OLDER than those of the limestones used to build the Great Pyramid. That sounds like a timing problem to me.@@PatrickKQ4HBD
I have a new appreciation for the scenery on road-trips after your videos
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.
Some people will believe anything!
Spiritual don’t make people laugh , stop smoking pot
Thomas A. If you really feel that way, touch a Holy Bible. Christ was before there was time. How long ago do you think that was? The Word of God is the oldest thing we know of. And nearly every Earthling has one Bible today. We can read God's word at any time. That's the true miracle. Love you Lord Jesu !!!!! 💋
@@tomgunn8004 while others have NOTHING to hold onto or even hope for. 🙏✝️🙏✝️🙏✝️🇺🇲🇺🇲🇺🇲🇺🇲🇺🇲🇺🇲🇺🇲
@@mawi1172 Speak only for yourself (w/out your religious faith), please.
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.
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.
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.
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.
Ah, road cuts. Where would we be without them?
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.
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!!
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 Scotland you have another "Great Unconformity", at Siccar Point. In some respects it is more spectacular than the nonconformity shown in this video. At Siccar, I think it is nearly flat-lying Old Red Sandstone resting, in angular unconformity, on older, steeply-dipping "transitional", sedimentary beds, indicating that the older beds were deformed, uplifted, levelled by erosion, then engulfed again by the sea before the upper beds were deposited. Understanding the significance of that outcrop is one of THE signal events in the evolution of geologic thinking.
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.
Ah, yes! I know that area well. For a few years, I led geology themed river trips for OARS on the Yampa River. Yes, I will add this to my list of places. Some great structures at Harpers Corner among other cool geology.
Shared with my friends in Wyoming. Very informative. Thanks.
Amazing to touch so many years… thank you 🙏
Great information, I am learning so much! Love your channel!
Canyon walls and road cuts are fascinating windows into what lies beneath the soil we tread and drive over. Great content 👍
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.
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.
What line of work has you dealing with these?
@@shawnwillsey I have a Stone and Preservation business in Southern California
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.
That is a majestic looking canyon. Awesome !
Cody, Wyoming, my home town. Never knew what was in my own back yard. Thank you!
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.
Yes, I've seen pictures of this and would like to visit someday. Thanks for the reminder.
Manitou Springs is west of Colorado Springs on the way to Pikes Peak.
Dsylexia set in
Wonderful Presentation. Thank you.
Great vid 👌, as always. Thanks 😊
Thank you for sharing your time and knowledge professor Willsey.
thank you for your time
Thank you so much! Absolutely wonderful. 😊
Outstanding! Thank you!
Another great video, thank you
VERY informative. Thanks so much!
Fantastic spot, great to see it. Thanks!
Wow, thankyou. It's fascinating to see this; much appreciated.
Very informative- thank you!
"and just like that I walked across the great unconformity" wow what a humbling and surreal experience.
Excellent! Great science and enthusiasm!
Well done, Thanks.
Awesome!! Thank you!
Amazing... Thank you!
Oh…this is exciting. Always learn something from your channel. Great Unconformity.
Very cool! Thanks!
Such a cool area. Stopped there several times over the years traveling to and from YNP. Thanks.
Thanks. Very interesting.
Thank you… love this topic
I was recently studying this canyon. Excellent.
I really enjoyed your videos and just subscribed. Thank you
Just Amazing!
Thanks!
Thank you Shawn! I so enjoy your videos. This one reminded me of the time my husband and I saw this Great Unconformity one mile east of Las Vegas, Nevada. We were following Albert Dickas’ book American Geo-Sites. No 51 was the Great Unconformity that you could see inside the Grand Canyon, but here it was unmarked 1 mile east of the intersection of Lake Mead Blvd and Hollywood Blvd in Las Vegas, at the base of Frenchman Mountain! 1700 mya Tapeats sandstone inclined 50 degrees on top of 1.7 bya Vishnu Schist, “broken exposures of reddish Vishnu Schist”. Really cool and memorable. I have the coordinates from the book of anyone wants to know. And a photo. Thanks for your Cody Wyo video.
Awesome vid! Rocks and Minerals with Wilsey, theory to practice
Hi Shawn, I loving all your videos and iam learning from you, you are so knowledgeable.Please keep up the good work. Im new to minerology, geology and gemology. Thank you so much.
Amazing! 👍👍
Hello from Cheyenne, WY!
I know this may sound nuts, but I appreciate what you bring the table even though I've been in the medical field for a career in the last 40 years. I worked for nursing agencies in three states and Wyoming had to be the most fascinating of them all, the other two in Nebraska and Colorado. I eventually settled down in Wyoming because it had so many factors that I was just in love with and one of them was the geology. And that's what's crazy I'm a medical as far as science is concerned but I love geology!
I spent some significant time on I-25 going north from Cheyenne to Northern Wyoming and Western Wyoming and I will never forget my time spent up in Thermopolis and the geological factors I saw there, including Chugwater formations like Round Top anybody (who's ever been to Thermopolis knows what I'm talking about) I've driven through the state park at Guernsey and a lot of fascinating geological stuff there, I'm not sure some of the rock samples I took home or petrified wood or agates.
So let's see you do a video about some of the geological formations in Guernsey and Thermopolis that would be absolutely incredible! I'm looking forward to it!!
Thanks so much for this video, as the canyon near the Bill Cody Dam is one of my favorite places to just stare in awe at the splendor of the rocks! 🙏 🤩 Whenever I can, I take loved ones to see Yellowstone, and I always go through Cody. Next time definitely going to stop and place my hands on this geologic marvel 🖐😎
Props for navigating that rugged terrain while holding the camera steady and narrating without incident. And all in one clip.
Great stuff Shawn! Way to tie in your other videos…so we have to go back and looksie🤣. Thanks.
Fantastic video which really shows what geology is about. Stumbled upon it only by coincidence.
Thanks. You have a new subscriber.
Welcome aboard!
Amazing to see the world through the eyes of a geologist.
Thank you 👍 On the Beach 👌
Love it, thanks so much! I majored in geology, and went to grad school, too, only to discover that learning geology is something I’m far more suited to than research. Now I’m an engineer, but I miss it a lot. This takes me back to my undergrad days, going on fiend trips and learning. Thanks for the nostalgia.
Also, thanks for representing geology on TH-cam! I’ve found great math and physics and astronomy and engineering youtube channels, but geology doesn’t seem to get the love it deserves.
Welcome aboard and sorry for the very late reply. Hope you enjoy the geology videos here.
Thank you, well made… wish I had paid more attention in my college geology claas
Randall Carlson reawakened my interest in earth's history. So glad TH-cam suggested this video.
"What's the cool feature?" It's all cool, Shawn. And fascinating.
Any plans to visit Wind River canyon north of Shoshone reservoir?
Your videos are perfect. Thanks.
Eventually. When I get back to that area.
Although I’m 17 I actually understand this very well since I study this stuff like crazy as a hobby. I fully understand what’s going on here.
Nice!
Very cool. I chose to get most of my college science credits in geology courses because it fascinated me. Now as an old guy it still fascinates me.
Wow nice
beautiful place
Another winner! Was there a Big Boy statue in a field off the highway on your way to Cody? Amazing area thanks for the close look!
Thanks. I did not see a Big Boy statue.
As always. Amazing. Question ? Have ya had a chance to see the folded rocks from the tram ride at snowbird yet?
I haven't been up there in several years.
Yes it's beautiful, born and raised in Cody
I drove that road a dozen times this summer Trout fishing. Too bad I didn't know what I was looking at. Good job on the video.
I accidently found your channel and am now your newest student. Thanks for to days lesson.
Welcome aboard! Enjoy perusing the existing videos while I continue to get out and make new ones.
Just. Wow!
I have been to two other places where the Great Unconformity is exposed. One is on Arizona route 87N between Peyson and East Verde Estates, Arizona near mile marker 260. Another is the Black Canyon of the Gunnison, Colorado. This Great Unconformity was supposedly formed in two Snowball Earth episodes during the 850-635 million-The Cryogenian Snowball Earth time period. I have heard that it exposed in the Ozark Mountains somewhere also.
4:30 the big rock across the Hwy makes me nervous for drivers .
To think that people want to stand so close to the edge of the canyon with it wanting to crumble .
Looking at the Hwy tunnels , some edges look like they want to fall over !
Great view
Awesome video! I was a science nerd growing up, but geology never captured my fancy. But you presented this in a way that really caught my interest. I live close to Red Rock Canyon in Las Vegas, this makes me want to go exploring. Thank you!
In grade school I was really into geology. I've still got a huge collection. I gave it up after talking to geologists, they all said that they never get paid enough for the hard work. In short they felt they were taken for granite!
I have seen this feature in a road cut just outside Las Vegas many years ago and it blew my mind then. Seeing this video reminded me of the experience. Thank you for posting.
Have you explored Clarks Fork Canyon near Cody? It's pretty amazing.
On family vacation, with the 1957 Plymoth, dad drove that canyon with the right side headlight out and the the generator kaput. 1962
I live in Riverton, so this is rad and something I can go check out! Look out for the Washakie Needles on your left if you go through Dubois and toward Riverton/Lander.
Didn't make it that far on this trip, but I will be back.
So cool and so different to what we have here in the North Island of New Zealand.
Please keep producing these informative and interesting videos.
Thank you! Will do!
Hoping to visit your country soon.
You should check out Fremont Canyon between Alcova and Pathfinder west of Casper.
Enjoying your channel greatly. As former geologist I’m getting to see cool places I’ve never been. If you want to knock off the great unconformity #4 try Camp Creek east of Melrose and north of Dillon Montana. Not only a great exposure of the unconformity, but of a paleosol, weathered zone, a fault, and pegmatite dike in the Archean rock cut by the unconformity.
Great suggestion. So many areas for me to get to still. I'll add to the long list.
One is never a former geologist. Geology is for life.
We have an unconformity in southern Ontario where the oldest rocks on Earth, the Canadian Shield, are overlaid with much later Great Lakes limestone. It's much the same relative ages as the Great Unconformity, and a striking contrast between the layered or lumpy grey limestone and the pink granite. A huge field of volcanos and many kilometers of surface depth were eroded away before the limestone was laid down, and everything above the limestone was scoured off by glaciers and dumped further south, where it makes a moraine that stretches across the province just north of Lake Ontario. Part of it ended up getting pushed all the way to the Atlantic, where it formed Long Island.
So cool! Here in Oregon our rocky outcrops are less than 50 Mya, barring exotics - my wife's from Wyoming, so I hope to see a trip to Cody in our future lol I'd love to get a nice contact hand sample!
I did a video near Cody last fall. th-cam.com/video/LQrUKemjDoY/w-d-xo.html
I have been a middle school science teacher in Cody for 20 years and just recently found your channel. I am working through your videos and really appreciate the content. I take my 8th graders to this site each year and unfortunately the amazing nature of natural history is mostly lost on them. Their favorite part is throwing rocks at the contact of the unconformity at the end of your video. I guess that’s better than nothing. When you look at the sandstone farther up the stratigraphy you see intermixed beds of shale. I find those almost as fascinating. I’ve always assumed it relays a series of transgression and regression of sea levels. I was wondering if you noticed that or could confirm my suspicions. Again thanks a lot for the excellent videos.
Great work on educating the young folks. You are my hero. Yes, there is some interbeds of sandstone and shale, which indicates rise/fall of sea level at that time.
Gosh, a few years ago I drove with my family from Minnesota to Yellowstone and stopped at that dam on the other side of those tunnels. Darn I did not know about those details nor do I ever remember hearing about the great unconformity being there. I think I might have heard of it existing but only in passing. A few years before that we were at the Grand Canyon and then lopped back home through Utah and I wonder if once again near your other great unconformity site.
In addition as a child I lived in Worland Wyoming not far from Cody. But never knew all of that geology. I just watched about the worlds largest land slide right near were you are as well. Thanks so much. This is fun to learn about.
Are you talking about Heart Mountain sliding off the Bear Tooth mountains?
@@k1j2f30 Yes that is one of the pieces that slid off. Another according to the video I watched is Rattlesnake mountain which I think is what was cut by the highway that Shawn was in. So that could be the reason the unconformity layers got to that location. I had not realize that until now. Did they raise up but then later slide there?
@@daleeason9687 I'm not sure, but the size of that land slide is mind boggling! Wish I could have seen it happen from a safe distance of course. Can imagine the sound and the earth shaking under my feet!!
Shawn, appreciate your series of educational videos. One question, is there any significant geochemical difference between the Precambrian rocks and the more modern plutonic rocks?
If you take age and angle, can you computer simulate/ backtrack in time historic contours? Or do we not have enough data for a large enough area to do so?
Excellent. So interesting to see that time lapse so clearly. Love the pegmatite. Wonder how the beach sandstone got to be sitting directly on top of the old granit , I mean what was originally on top of the granit ?
Other, younger rocks were on top of the sandstone, but they were eroded away before the Cambrian sandstone was deposited. In other locations, we sometimes do see some of the intervening rocks, like the Grand Canyon Supergroup in the Grand Canyon.
@@shawnwillsey Thanks Shawn
@@shawnwillsey
So to get the feldspar mixed with the granite there needed to be a mixing pot somewhere, right? Was the granite deposited before the land uplifted out of the sea or after? If after how did it get sediment above it, obviously deposited before the rockies uplifted. So was the granite extruded in an underwater fault? I'm confused
Right, how many hundreds of feet of granite had to be removed before this stuff became exposed so that it could be overlayn? In other words, how deep in the earth did this granite form?
@@Michael-rg7mx The feldspar is one of several minerals in the granite. The granite is magma that cooled slowly underground. Much later, it was uplifted and eroded to near sea level, allowing the sandstone to be deposited above it.
You should go to Kootenai Falls in northwest Montana, the elevation gets deep in the canyon exposing folded belts of rock and ancient algae fossils
Merci beaucoup, I appreciate these videos. I took a geology class at a central Wyoming community college and it was fascinating. My only regret is that I'm colour blind and rock identification was a drawback.
WOW!!!
I saw this Uncomformity in June going west on this highway. I wondered about it as I went by in the vehicle.
I watched a video by Myron Cook in which he talked about the landslide that moved huge blocks of mountain out into the basin in this area.
The GU is a myth!
Shawn, are there any places where Proterozoic rocks are exposed upon the same Archaean basement? That would fill in some of the lost history in the Archaean-Cambrian Great Unconformity. There is evidence of ice ages down there in the Proterozoic, but I'm not sure if the the GU is exposed under Proterozoic rocks anywhere. It would make a good follow up to this one - closing part of the gap on the GU.
Cool
Great informative video .................... loved those pink pegmatites .................
Hello Shawn, you may have discussed it; however, I am pretty new to studying the geology of the west and will be taking classes this Fall, but do have a quick question.
What are vertical dividers (for lack of better words) in the rock towards the end of the video?
Drill holes used to blast rock and make the roadcut.
Didn't even know what the title meant but still fascinating.
Check out hwy 141, just south of Grand Junction Co. Uni-weep Canyon.