Grand Canyon's Iconic Great Unconformity: 1.3 billion years of geologic time! 

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You really know how to get the camera right up to great examples of what you want to show. It makes for very good videos that are easily understandable. Thank you.

Your talks are so interesting, I wish you were my professor. I could listen to you all day.

Amazing stuff Shawn. Please keep posting these educationally fascinating vlogs. You are a wonderful teacher!

Thanks for this clear picture and explanation of the great unconformity. What an incredible place. Love seeing the river.

Plasticity and lubricated nature of landforms sliding against liquefied bedding over basement rock. Thank you SOOOO much for your much better back and legs that get me the vicarious field work.

Loved this video. The best one so far as it shows up close the distinctive strata layers back to over a billion years. To see it so close was amazing. I definitely shared another of your videos to Facebook. Would love to see more videos of this trip. If you could zoom in on any marine life fossils would be great. I wonder if the seas here were to shallow for the sharks of the day back over 200 million + years. Finding a tooth to see would be epic. I don't think they can be taken out, but a picture with one on the hand or a hand next to it's embedded site would be really something to see.

Great Unconformity would be a sick band name

Thanks for the views and the video. While in school (to become a geologist) we hiked to the bottom of the GC and saw the contact, but your sites showed a good deal more about the nature of the Tapeats than what we saw. The sandstones, grits, and conglomerates don't look that old, but facts don't lie. Sure, we were impressed by the unconformity, but thinking about it now after a long (but very short in geologic terms) life as a geologist, soon to join the record myself, one begins to understand just how much can be read from the nature and meaning of that contact.

Amazing timespan.. mind boggling thank you for boggling my mind again!!😊

Excellent video as usual. An amazing window into deep time. Makes a human lifetime seem trivial.

It was left unsaid in the video, but presumably that contact also represents the ground surface at the moment where erosion waned and deposition took over--as this was in a coastal setting, perhaps it looked something like the rocky coasts of CA/OR, with a wave-cut bench of pitted rocks that enclosed tide pools in the upper reaches. I'm always fascinated by those kinds of windows in time where we can almost see exactly what the landscape looked like. Each one of those rocky cobbles at the lowest layer was dislodged from its source somewhere upstream, then came to rest on the Vishnu schist to be buried--frozen in place for us to see 500M years later.

Great video! (My one grand canyon experience was life-changing.) This helped me better understand the Great Unconformity. Just gorgeous, so appreciated, Shawn.

Thanks ah so nice. Thanks for taking us there!

Spectacular site. Awesome.

Well that gave me goosebumps ❤️✌️👍

Shawn, thanks - watching this video was a moment lost in time. My understanding is these features in the Grand Canyon are accessed through wining impossibly oversubscribed lotteries for the 10-day whitewater trips to the Colorado River section, and, with reaching the Blacktail Canyon, are subject to the likely but not always given scheduling and interests of the specific tour group. Your sharing this expert "hands-on" reveal of the striking Great Unconformity is an understated sharing of a special adventure.

In 1995 I was fortunate to be on an environmental impact expedition down the Grand Canyon. Among our number was a geologist from NAU in Flagstaff who led us on a hike of Blacktail Canyon. Your rendition of the Great Nonconformity took me back to that glorious experience. You are a gifted communicator using the web the way it was first imagined. Bravo

More, please!!

The Great Unconformity is a really amazing thing and I've never heard or seen it explained so well. You must be having an incredible time on this journey! Thank you for giving us a look at what you're seeing.

An incredible piece of Geological history! Just awesome. Siccar Point in Scotland is also another extremely rare example of where you can see what is thought to be part of a 'Great Unconformity' (or Huttons Unconformity) along with the Grand Canyon sequence ( Powell's Unconformity) . I visited the Grand Canyon 25 years ago now from the UK and I was just blown away by it. Such an awe inspiring place to visit and get up close to some amazing geology. You have the best job in the world Shawn!

HOLY SCHIST...what a cool video...much respect from Baltimore

Very cool seeing it up close and personal.

Thank you very much for this great video. I really appreciate you sharing that knowledge.

Wow, just wow

Truly beautiful and amazing!

I love your channel! So interesting learning about our earth!

That is mind-blowing, Shawn. Just astonishing, the contrast between layers. That place is so beautiful. I wish I could see the entire lifespan of the canyon in ten minutes. I bet it would be amazing to see.

Excellent video. Thanks for posting.

Loved this video. It took me back to my Grand Canyon rafting trip in 1968 when I was 14. I still have a photo of the “wavy” rocks that had been sheared and the horizontal strata above them. I was fascinated by them then and enjoyed your explanation of them now. Thanks.

Awesome, in the true sense of the word.

Really awesome video.thank you so much for posting.

Awesome explanation of an amazing place!

Wonderful place, mind blowing. Cheers

Joining from Germany , just found you and these layers interest me extremely for their old age and how they were formed, Great channel, I took an abo of course , thanks a lot !

Thanks for sharing. Very interesting !

Thank You for a great video! Very Informative!

As Stanley Beus, NAU Geology Prof used to say in 1979 (of the Tapeats/Basement contact); "If you listen carefully, you can hear the waves crashing on the ancient shoreline!" Actual quote from a field trip! Great Professor btw.

this is the best video I have seen yet on the Great Unconformity- excellent work!

Amazing, tks!

That was amazing, thank you!!!

Very informative vid and the scenery is just breathtaking. Thank you! I wish I could be there one day!

It's pretty crazy when 340 million YA sounds kind of new. What an amazing place. Thank you for showing us this .

Great episode Shawn and remarkable site you picked. GCNP is such a magical place; hope you had a great trip.

chapeau Shawn - great style

I’ve been to both N and S rim of Grand Canyon. I had heard of the great unconformity but have never been down in the canyon so it was great to be able to see it in your video.

Very interesting!

This is so cool. Thank you.

So cool! 👍🏼

Fascinating! I just visited the Grand Canyon and Bryce Canyon, and was overwhelmed by their size and their beauty, but had sooo many questions! This video answers some of them, thank you!

Just discovered your channel. It’s terrific! Subscribed with notifications on. 👍

Hi Shawn. Thanks for the great video on the GC GU. 1.2 billion years gone (in the blink of an eye). Hard to wrap my mind around that. Thanks again.

Thank you for yet another great video allowing me to see up close a geologic wonder I'd never be able to visit. The Great Unconformity is mind boggling, not only for the length of time involved, but for the sheer volume of material that must have been eroded. It would be so interesting to see what that would have looked like prior to and during the erosion process.

Fascinating 👍 thx

You know, as an electrical engineer this is very explainable. Even that great mica crystal vein you found. But usually these are much smaller in the lab :)

Outstanding!

Thank you!

I've been to the top of the rim, and wondered what the bottom looked like. Thanks for this video, Mr. Willsey. Subscribed.

Fun trip thanks

Very cool!

mind blowing!

Sure love your work

Wish i could visit sites like this. Beyond fascinating.

This ris eally fascinating, though i wish these video's were longer 👍

Thanks!

Wow. So cool. This is one of the most thought provoking subjects I know. Starkly terrifying in a way. The planet is so old. Our lives are so short. Your hand on that spot in time. Yeah buddy. What a great day!

I love rocks in every form. Always drawn to them. Started out as the pebble pup. And now at 45 y.o., I’m proud to admit I’m a rock hound. I’m forever looking down when out and about. Doesn’t matter where. Generally come home with pockets of rocks. That said. I’ve learned a few things along the way. What you are looking at is basically looking like a mud flood. Except sand. At a tsunami pace I think. It would explain the smooth areas sitting on top of the rock with larger chunky areas. I don’t know the elevation of the quick change between the layers. I wouldn’t be surprised if it was the same in other parts of the US where it’s found. They had to call it something other than flood created. They try to stay away from everything/anything giving weight to the biblical flood. And the sand layer isn’t as old as they say. When compressed and has lots of silica, it drys and hardens with a quickness due to drain ability and heat. If you walk out to a beach and grab a cup full of wet, packed sand, take it and set it on like a heated surface. And let it heat up for hours. I used a copper crockpot looking thing to test the sand battery idea. It’s how I come to understand what I have. When I checked later, it wasn’t all solid but there was chunks that I couldn’t crush with just my hands. It was solid.

Oh wow!

I have many times read about the Great Conformity (whenever you read about the geological history of the Grand Canyon it is always brought up) but I have never actually seen it shown up close and personal like this. [Also, about a year ago I watched that National Geographic: How The Earth Was Made | The Grand Canyon Explained and I don't remember them showing this dramatic contact.] So this is great.

Great vid Shawn! Great to see the GU so clearly! I dont think we the GU in Western Australia, but there is a small remaining sliver of an massive unconformity near Perth that is between 3.0-2.6 billion year old gneisses and granites of the Yilgarn Craton and a Cambrian (although its not been possible to get an accurate date) transgressive unit of fining upwards conglomerates, sands, silts and mudstones. Sadly the actual contact is hidden by overburden where I have access to where it would be (it's visible in a private quarry nearby apparently) but it's amazing to wonder what happened in that gap, especially as there were probably 2 supercontinent collision and breakup stories that impacted Western Australia in that time period.

Finally, an actual explanation & detailed images of the GC currently having incredible exposure by media lately….!

Thanks for taking us along. Those are really old rocks After my geology study of the last 18 months i understand so much more than when I went on a ranger walk near the rim of the grand canyon. This video is reminding me ju how young the rocks here in Central Washington are. The scenic views you show are so very stunning. This summer through videos I'm seeing a vast range of rock ages, from 1.8 billion in the grand canyon to a few days old at the Iceland volcano. I can't help but wonder how time of erosion went on before the sandstone began to deposit. I suspect that there is not a way to truly determine what that time was. Thanks.

Thanks. Planning to visit the area this fall. I always find myself wondering about the geologic history of the landscape as I travel. For example, the colorful banding in the Badlands of WY. How many years of deposit and erosion am I looking at and what was responsible for the color in the layers...? So much to learn in one short lifetime.

Do you have any published lectures? I'd love to see them.

so this is why I find those rocks on Mars so interesting to look at!

Great video, Shawn. Nice to see that the NASA shirt is still holding together.

Great mystery..really

10 day trip, always wanted to do it. Only ever walked from the south rim to the north rim.

"The biggest part of the stratigraphic record is missing...." (this was more or less what our Prof used to state (almost unnecessary to say that he wasn´t a fan of global sea level charts produced by sequence stratigraphy nerds)). Thank You!

Thanks very interesting. I have trouble walking or driving by a cliff or rock wall and not looking at the various layers.

at 5:23 you show i see some green rock in the right half of the screen. what can you tell me about that? it's remarkable the variety of colors, texture, and configurations in the schist. if i remember correctly, the tapeats sandstone, along with the bright angel shale and muav limestone were laid down during the Saul, cratonic sequence? always enjoy your videos. thanks

After a holiday, I'd sit on a large chunk of driftwood while overlooking the ocean, eating a licorice stick -- I'd contemplate this.

I love this one, having never been down there it's just really wonderful to see up close. Would a similar unconformity develop if you had many millions of years of beach deposits on currently exposed / glacial scoured shield rock (thinking here in canada)? Is that a rare process or do the pre-cambrian basement rocks regularly (in geologic time anyway!) go through a process of being buried and then eventually uplifted and exposed?

Thanks

It's amazing looking at the layers that look like layers of pasta placed on top of one another, each layer representing millions of years of sand deposit. And the amazing thing is that the geographical settings are still changing, and change so slowly that we will never witness any future changes in rock formations with the human eye. You would probably have to sit on a spot and observe an area for 10 million years to see any movement or change of less than an inch. It's mind-boggling, and it makes you think that on the scale of things, us humans live for a microsecond when you consider the age of these Earthly rock formations and also the movement of the continental drifts..

I would love to go hiking with you! New sub here, hello from Montana

The most interesting experience was a community college geology class in Central Wyoming. Unfortunately being colour blind prevented me from being able to appreciate all the nuances of crystalline structures, but just the mechanisms in place were inspiring.

Wow, some of that looked just like wood, I hope too go there soon.

Cool, where I live everything above the pre-cambrian level was scraped away by the glaciers.

What are the bigger clasts in the Tapeats on the contact? Are they made up of the schists and granites below, some other igneous or metamorphic rocks from somewhere else, or are they something else entirely?

That was some great material. Thanks for posting! If I may ask a question, how does Siccar Point relate to what goes on in the Grand Canyon? Both locations seem to display perpendicular layers and "missing time".

How is this idea?: 1.8bn years ago there was a big & high mountain ranges with the schist and granite in their deep core was throughly eroded and cut by a huge chunk of glacier about 5bn years ago, and turned into a plane lock surface which was entirely covered with a large water body after a rapid melt down of the glacier. Then forming of the sandstone started.

So how do you think all those sand particles you mentioned got there?

Great video. Mt Everest is 5.5 miles above sea level so the Vishu Schist was twice that distance below the surface before erosion and uplift brought it to sea level. I visited Blacktail Canyon on July 25. When was this filmed?

Is there any speculating as to what rocks had been between the Tapeats sandstone and the older Vishnu Shist rock beneath and what happened to it? Or is there a place where that layer might still be intact somewhat?

Would the missing time/layer coincide with ice ball earth? Thank you, nice video.

Great video. The "Missing" billion years seem hard to accept. Shouldn't there be massive erosion on the Vishnu?

Interesting, a rare seen place on the planet.

The so-called missing geologic material was processed into the material that comprises the sandstone. The so-called missing rock layers were ground-up to make the sandstone.

There's a second older "Great Unconformity" between the block faulted Grand Canyon Series Precambrian age sedimentary rocks and the same Vishnu Schist exposed at Black Tail Canyon. There is an approximately 400 million year wedge of "missing time" represented by 12,000 ' of gently tilted sediments easily accessible from the North Rim trail down to the Phantom Ranch. That could be a nice follow up video! Beautiful ripple marks are exposed preserved in the Hakatai Shale. Lower down in the section below the Hakatai Shale are the the oldest fossils in the canyon which are stromatolites preserved in the Bass Limestone at 1,200 million years old. I found those beautifully laminated stromatolites in a "float" boulder probably derived from the basal conglomerate of the Bass Limestone on the trail at Phantom Ranch. Very cool!