The Great Unconformity: a geologic feature spanning 1.3 billion years high in the Wasatch Mtns, Utah 

I love geology and your enthusiasm when informing your audience. Thank you.

For those out in the Las Vegas area, The Great Unconformity is also accessible right off of Lake Meade Blvd. as it begins to make its way over the hill to Lake Meade, on the south side of the road. There is a sign there, pointing it out.

Pretty amazing being able to actually touch the conformity and bridge it with both hands, such a clean sharp line. Massive Quartzite deposit !

A great video made in somewhat difficult conditions!

I’ve hiked exactly there and also above Honeyville to hunt trilobites. Great specimens.

Thank you Shawn. As a finance executive for a number of Australian resource companies, I was always impressed with the presentations given by our exploration geologists. By subscribing to you presentations I can continue to be impressed in my retirement.

I am Miner ! I look for Pocket Gold in my region. Have found some spectacular Rock Deposits in which I display in my Restaurant. But unraveling these Rock structure’s and identifying them is really what it’s about for me. Ty just found your channel and love your take on it for the common person. I’m from the Klamath mountains of Southern Oregon so the Geology is unbelievably complex with faults folding an covered by vegetation. Makes for a Awesome challenge.

So, long story but I became a geologist when I took intro to geology at BYU and touched a billion year old rock at Rock Canyon on a field trip. I left BYU (was not meant to go there) and finished by degrees at UTEP. We have the unconformity in El Paso and 500 million years of missing time is one of the most intriguing things to me still in geology. You got a new sub today. Look forward to more content.

Another good show Shawn! Thank you for sharing your knowledge with us brother. Educational and entertaining. Keep the videos coming! Jim

Thanks! I felt as if I were there and listening to you directly standing right at the edge of the cliff. Somewhat ominous sky fitted to the feeling of jumping 1.3 billion years from grey to cream.

Cool! I’m heading to Logan next week, will keep my eye out.

Shawn, thanks so much for making this video! I grew up in Willard and spent countless hours hiking all over those mountains and though I've heard of The Great Unconformity I had no idea there was such a good example of it literally in my backyard. This gives me an even deeper appreciation of that area that is so near and dear to my heart.

Very cool. Thanks for sharing that spot.

1.3 billion years is really hard to wrap your head around. I love driving by the Wasatch range. Great to learn about some of the history I'm always curious about. thank you!

Great vids. I'm a retired geologist living in Prescott, Arizona. We have a great exposure of the Great Unconformity here between the Tapeats and the Proterozoic basement rocks on Route 89A going up the west side of Mingus Mountain. I love pointing it out to visiting guests. Keep up the good work. We love going thru Idaho to visit son in Bozeman, MT.

I enjoyed a few hikes up Ben Lomond and noticed the fun rock differences in that area. As you panned over the Great Salt Lake and Willard Bay, I think Promontory Point was visible. Just to the north of it was then Thiokol, where the first space shuttle motors were developed, built, and tested. During the first test, seismic activity was noted on the Wasatch Fault, but the NASA contract was firm even though USGS asked that the testing be stopped. I hope some day you can do a presentation of the Wasatch Fault and its connection to Yellowstone. Timpanogos Cave is such a fine place to see the fault's vertical displacement. I've heard that the geology building at Weber State is built atop the fault itself. Fun connecting times.

Interesting. A story on the coal ribbons along US 6 south of Castle Gate UT would be nice.

Love this! Not sure why the algorithm picked this video for me, but having grown up in Box Elder and moved away long ago, it’s wonderful to learn something fascinating about these mountains I saw everyday as a kid.

Thanks for sharing this portion of the fascinating story of earth's past. Now that I've found your channel, I will very much enjoy catching up on your expeditions. Subscribed.

This is one of the most interesting videos I’ve ever seen. I love learning and this geology video is the best. Thank you.

In Western Colorado there are the Black Canyon National Park and Colorado National Monument, both of which display the Great Unconformity in exquisite detail. In Colorado National Monument, there is a basement that's 1.8 billion years old, intruded by granites that are 1.4 billion. Then there's the Triassic Chinle Formation on top of that, illustrating a mere 1.2 billion years of missing time, which I find amazingly close to your 1.3 billion in the Wasatch.

Such a span of time… it boggles my mind trying to imagine this. Its amazing what stories rocks can tell

Your lecture reminded me when I was exploring South section of our CENTRAL PARK NYC...bed rock there is amazing! Huge mountains were there when two tectonic plates collided eons ago to form the foundation of MANHATTAN.

Thank you for the informative video, It is good to see lots of people really enjoying Geology.

A great video on a really interesting topic! You do a great job making geology more accessible to those without a geology degree in these videos.

I remember seeing what I believe was the same unconformity in the Wind River Mountains when I was attending my geology field camp. I also saw it at the bottom of the Grand Canyon. Just amazing knowing the history and actually being able to put my finger on the contact!

I really gotta go to Utah. Every time I see a picture or video from there it’s just absolutely beautiful.

Really interesting - thank you for the lucid description. Something I've wondered about since seeing that in Grand Canyon

THANK YOU! I went to USU and often drove past this section of mountains. As a kid on the east coast, I always imagined all the "Rocky Mountains" would look like this section. Always one of my favorites. Thanks for the video!

Hi Shawn, thanks for pointing this out. I worked in the San Juan Mountains of SW CO looking at 1.75 Ga metavolcanic rocks now gneisses and amphibolites overlain unconformably by 1.65 Ga quartzites and slates that are folded and thrust faulted. There was a second "great" unconformity above these quartzites and slates with Cambrian sandstones through Pennsylvanian limestones on top of the exhumed Pennsylvanian paleotopography. This is visible along Lime Creek off of US 550 north of Durango, CO near Molas Pass. Another example can be found in Uncompahgre Gorge just south of Ouray, CO where the folded Proterozoic quartzites and slates are overlain by Paleozoic limestones. I"ve published several scientific papers on this area. I'm intrigued by the Cambrian Quartzites and conglomerates above the 1.8 Ga gneisses and amphibolites. Reminds me of the San Juan mountain's rocks in the Needle Mountains area.

Great explanation! Being from Colorado, I am more familiar with the Great Unconformity in various locations around the state. I was not aware that it also appears on the Wasatch front. One of the easiest and best locations to observe the Great Unconformity is along i-70 in Glenwood Canyon. The dark ancient rocks there are overlain by limestone layers which contain caves and other Karst formations. Not being a geologist, I don't know the time difference or whether the limestones are metomorphic. But the demarcation between the rocks is clear and can be observed in multiple locations through the canyon. Another great location to observe the Great Unconformity is at the Uncompahgre Plateau near Grand Junction. You can hike down (or up) to the time gap (or drive past) in several locations within Colorado National Monument, in several canyons draining the plateau, floating the Colorado River across the state line into Utah, and to the west at Black Canyon of the Gunnison NP (the gorge is cut into the Pre-Cambian rocks but overlain by younger rocks). In the Uncompahgre Plateau area, the Great Unconformity is very beautiful, with the very dark (black) older rocks overlain by very red shales(?) of the Chinle Formation. The Chinle and the other sedimentary rocks above it form traditional desert canyon topography with sandy and rubble filled streambeds andgreat sandstone cliffs, while the small streams have sculpted narrow inner canyons into the dark Precambrian rocks with waterfalls, pools and smooth rocks. One other thing, of which I am proud. We were recently in Albuquerque and took the tram to the top of Sadia Peak (highly recommended). About 2/3 of the way up, I looked out and pointed to a demarcation in the rocks and told the tram operator, "Great Unconformity". He was kind of amazed that I observed that, as was I. I guess I have seen it enough times in various parts of Colorado so that I can instantly recognize it. I was not expecting it in New Mexico, or that far east. It must really be quite extensive and found in many places throughout the western U.S. I hadn't really thought about it, but I guess it exists within a couple miles of my home in Littleton, CO and all along the Front Range of Colorado where Pre-Cambrian rocks of the foothills are overlain by sedimentary rocks such as the famous Fountain Formation (Red Rocks Amphitheatre) - it's just that the line of demarcation is not as distinct as observed in some of the western canyons. Thanks for your video. God bless.

Cheers from a fellow Brazilian geologist!! What a great RU-vid Channel u have.

I love northern Wasatch. Good hiking. We also have a great unconformity down in southern NM. Mud mountain in TorC.

Been working across the lake out near Wendover in the crater islands. Looking at Devonian/Cambrian limestone intruded by Jurassic granite. It's been a goal of mine to do some videos like this with some brief diagrams, but I didn't think I have enough credentials. Good video

Nice to see that over 12,600 other people were interested in this.

Fascinating. Thanks.

Wow, interesting stuff and presented in a useful way. Thanks for sharing.

Great film, I got dizzy from here. Camera quality, photographer, or my waning balance? Thanks too for the clear explanation

Great exposure of the Great Unconformity. In southwestern Utah old highway 91 goes right over the Great Unconformity in the Beaverdam mountains, a bit easier access, but not as pronounced as here, some delightful migmatites in the Precambrian layers as a benefit!

Very cool to explain the earth we see everyday but don't really know how it's formed, good to physically show the terrain and talk about how it formed, excellent learning program, thanks for your efforts.

Well hello sir! I could listen to Geologists forever. Looks like you are one of my kind, going the extra distance for rocks. Sub'd

Hey Shawn, I have been loving your videos! On a topic unrelated to this video... As a local to SE Idaho, I would love to see your breakdown of the Menan Buttes north of Idaho Falls, I have always found the limited amount I know about the geology of them fascinating. On hikes up there, I have also noticed what appeared to be sandstone or some other sedimentary type rock up at the top along the south part of the rim that I have always been interested in. Also the island park caldera could have some interesting geologic history.

Thanks Shawn for another great video "field trip!" I've really enjoyed learning about the geology of the Utah/Idaho region through your channel. The Intermountain West geology is so fascinating that Earth Science has become a real passion and study for me. Soon, and with a bit of regret, I'll be moving from the mountains to the flatlands of the Great Lakes region -- a whole different type of geology -- no mountain building events, volcanic fields or an active 800 mile earthquake fault system ... though I'm sure the geology will present itself and I'll find equally fascinating geologics all around me. Maybe the Mid Continent Rift system for a start! ... lol! Happy geo-explorations!

Thank you, I automatically subscribe your channel, btw.. why youtube is so late recomend this great channel?

That was amazing I’m on summer break and it felt like I was in class thank you!

Another amazing video! I live in the area and am mesmerized by that formation! Appreciate the analysis!

Love learning about all the geological processes that make up our region. No spills over the edge though! You know what they say about geologists having rocks in their heads! 😅

I always wondered what made those certain rocks so old looking and craggy. Some rocks I see are huge, with deep, old pitting just like these. It makes sense they came from so far down.

Thanks Shawn, love your explanation ....

Thank you for the lesson and for the beautiful scenery. Glad to be a subscriber.

I'd love to go on a road trip through the Rockies with a guide like this

Enlightening

Being from Germany I probably will not get to visit this unconformity in person. But now that we have Google Maps I can zoom into the aerial images of where you are standing and see it for myself. I love the technical achievements of today.

I was just there in May at the KOA down the hill. Beautiful features and out croppings.

Great info. I love your videos.

This is great! Thanks!

Beautiful video.

I'm late to the party, I know. When we went to see the total solar eclipse in 2017, I saw this spectacular front of the Wasatch above I-15 in the Willard area, and I took shapshots from the moving car. I hoped to find a good guidebook or description of what I was seeing, but I found almost nothing online -- which surprised me. Thank you for this explanation of at least one aspect of the mountain front.

Very neat. When I was a kid my pops told me that the color difference was the wasatch fault. I was in middle school before I reasoned that it wasn't the case hahah.

That quartzite layer goes all the way into Washington and Idaho.

Awesome! Is the missing material from the unconformity represented in other areas?

Thanks!

Thanks so much for sharing, you've sparked an interest over here in Taiwan! Are there any books you'd recommend for a hiker who wants to better understand the story the rocks tell as they wander up a mountain?

Superb, got my subscription, cheers to you 🤟

Hey Shawn love your videos man. Was wondering if you could do one on the Farmington canyon Complex?

awesome thank you

Wow so cool! We climbed the most prominent spire to your south and I remember climbing up and over the black rocks and the transition to the lighter colored rocks. At that time I had never heard of the Great Unconformity but some how knew it was important as it is such a dramatic change in the rocks. What a beautiful place and the view back over the Great Salt Lake was pretty cool with the sunrise. It took two times to get up that. How was your down climb ours was pretty sketchy :)

Fascinating, thanks. New sub

Careful!!!! Great video!

Shorelines of sand deposits and gravel layers deposited above it by river flow are 1/2 mile above visible farm fields that are higher then current sea levels .

Cool video thanks

I will need to look next time. I drive by at least twice a week.

Thanks.

Sometimes a formation pinches out against an unconformity and forms an hydrocarbon trap. These can be some really big oilfields. They are kinda hard to find but there are more to be discovered.

It looks exactly as one could descibe. Really old rocks being covered and being pushed up along the top of the much older rock underneath. The newer rock covers the old like a veil in the wind. Not so uniform across either because I'm pretty sure there was a great inland salt water sea here for millions of years. It is amazing how much higher the land got after even more millions of years afterwards.

There's another example of the Great Unconformity (though less dramatic than this one) behind Boulder, CO, where the Fountain Formation (of which the Flatirons are made) lies on top of the bedrock Boulder Creek granodiorite. At Contact Corner on Flagstaff Road, you can actually touch the contact, which spans 1.3 billion years, as it does here...

I've straddled the same unconformity in Broken Hill, Western NSW. totally awesome. (The basement rock there is pretty messed up - schist to gneiss - I found a pegmatite intrusion that was folded in three different directions...)

Do we know where all that eroded rock ended up? Or is there simply no way to know?

This is visible just outside Las Vegas, on Lake Mead Blvd, on the way to that lake. There used to be a big display about it, but it was destroyed by vandals.

That’s really interesting. If that’s the spot I’m thinking of I have seen it a number of times while traveling on I15. I always thought it was fun to look at the up tilted band of rock on the mountain that looks all wavy until you view it from the north around where the port of entry is on I-15 at mile marker 361, from there you can see it is one lined up band going up the mountain.

Hi Shawn! We really enjoyed this video we've looked at this section for a long time trying to figure out the stark contrast. What is the layer above the sandstone? Because you have the metamorphic basement rock, then the sandstone, then it goes back to another darker section of rock. Thanks for the information!

Do you have a comment on the new crack in Turkey after the recent earthquake? It has amazing geological features. A unique opportunity to experience an active fault breaking layers of rocks. Beautiful! Do not misunderstand what I refer to, the pain, suffering of all is a tragedy to humanity and I am deeply sad.

The Great Unconformity can be observed on the west side of Frenchman's Mountain in Nevada near Las Vegas.

I don't know I you have done anything els3 on the area, but the whole of the ogden end of the watch is amazing. Would love an indepth view on the area from you.

Correction, 1.8 BY is MesoProterozoic, not Archean, I sometimes make similar slips when lecturing in the field where things are so dynamic.

Danke!

Question: (different topic but this location is just right for it) You mention the Wasatch “front”. Recently I learned the term “break in slope”, which I’m guessing can be applied to a front. West of you the terrain is dramatically flat. You mentioned uplift of course. My question is, is there a north-south fault at the base of the front? Is there always one, e.g., along the Front Range at Denver? Thank you so much for these informative mini field trips!

2:55 Sir, 1.8 bln years ago is not Archean Eon but Proterozoic Eon. It was a time of Columbia supercontinent.

I've seen those mountains but never walked them, really interesting. BTW I expected to see you disappear any second.

Wow love the conglomerate Quartzite.

Shawn, did you know all of these areas in Willard are now blocked off from public access? They are destorying this whole mountain range from open-pit mining. Is there anything that can be done to protext this geological history?

really spectacular. i remember hiking down into the Grand Canyon and seeing for myself the great unconformity and trying to get my head around the timescale, something a person cannot do, try as he may. You have given me one more must see destination! i'm curious as to the forces that brought these rocks to the surface and tilted them. Was the continent you mentioned that collided with N A Rodinia Are the Mojave and Yavapai orogenies in any wise implicated here, or is that another story entirely?

would love to find a transformative magma/hydrothermal intrusion into something like those pebbly quartzites @7:25 should make some lovely stone.

You describe the older metamorphic and the younger quartzite rocks/layers, but you didn’t answer the questions as to why they are adjoined or what happened to the 1.3 billion years that separate them. I would love a video that answers these questions. Thanks.

Shawn: Dude! You get so close to the edge. You are freaking me out!! Thanks for the great videos though.

Hi Shawn. As a Less than Layman, what is the causation of the sedimentary stratification. What took place that separates the sedimentary layers so that the deposits are not just a continuous layer. Is it just suggesting seasonality? Also have you read the hypothesis that glacial erosion during the Earth Snowball period wore away the deposits and that led to the Cambrian Explosion?

GREAT Video and thank you for explaining... Question: are there Quartz Crystals inside of those rocks? Also.. did I actually see Seashells in the " Pebbly" looking Rock? Thank you again for the uncomformity lesson.. its SO HARD to wrap my head around the AGE of these Rocks! Mikeyo-NJ😎

Interesting and dangerous looking.

Shawn, it would be interesting (to me, anyway) if you could describe the Wasatch Mountain front as it is visible from I-15 in Willard. I appreciate the close-up analysis. But I took photos of these mountains from I-15 when we were heading to Idaho to view the eclipse in Aug 2017. I was left to wonder what I was seeing in the photos.

Thanks for producing this! Climbing alone would have been difficult and you are still understandable above the wind noise. I'm interested in why early on you didn't mention that quartzite was a metamorphic, the other metamorphics, though, being well discussed. This seems to be to me, as a non-degreed, non-academic, to be a logical point to mention how sandstone can alter to quartzite. To me, not knowing anything, "blocks of sandstone" immediately calls up all things sedimentary, that rock type seemingly out of place on the hill. But knowing that quartzite is a metamorphic, well, everything now seems consistent. Again, thanks for all your efforts on educating people on the natural world.