Every Layer of the Grand Canyon, Explained

the Grand Canyon is like a book A book that tells the story of Earth by reading this book we can peer deep into the animals of our ancient Planet this book can help us understand how and why our planet looks the way it does today how it looked in the past and what it might look like in the future it can help us understand the history of life and death on our planet everything from the simplest single-celled organisms to our earliest tetrapod ancestors from the diversification of life to the devastation of mass extinctions we can see ancient oceans and primordial forests and bygone deserts this book can teach us so much about our journey on this little blue dot we call home and we can see it all in the Grand Canyon so if the Grand Canyon is like a book then the individual layers of rock within it are like the pages to that book and if you can read these Pages you can read this book so today I will be your librarian on this geologic Journey Through the layers of the Grand Canyon and I will help you learn to read the pages that together tell the story of Earth my name is Cameron and this is national park diaries I tell stories from the world's protected places they are fun I hope meaningful educational stories about National Parks public lands and protected areas today's story is about Grand Canyon and it's about geology but I cover lots of topics from ecology to biology to Natural History to regular history and everything in between pretty much if it has to do with a protected area of some kind I will talk about it so if you are interested in that don't forget to subscribe and hit the Bell thing so you don't miss an episode I also have a patreon where you can get three extra videos a month plus access to my Discord so check that out if you are so inclined that's patreon.com national park diaries alright let's dive into the layers of the Grand Canyon because as I said understanding the individual layers of the Grand Canyon is a way for us as puny humans who have only been around on this planet for like basically no time at all geologically speaking it's a way for us to make sense of the history of our world to understand where we came from and how we got here and why our world looks the way it does today rocks help us understand all this because they're like little snapshots into various periods of Earth's history we can see and touch and feel these rocks and thus we can see and touch and feel that history one layer holds the clues to things that happened millions of years ago another layer hundreds of millions and still another layer billions of years it's all laid out for us here in a grand display at the Grand Canyon now before we get started on this tour let's go over a couple of ground rules for one where going to be talking about generalizations here we're going to be talking about the main layers of the Grand Canyon as well as our best guess for their relative ages and the composition of the rocks that make them up that doesn't mean that there aren't other layers or layers within layers or sub layers or rocks of different ages within those layers or different types of rocks within those layers there are the geology of the Grand Canyon is very complex and my goal here is to simplify things so that we're not here for literal hours but also so that you can get your head around the big picture the broader context of what these layers of the Grand Canyon are able to tell us about our planet's past and not get so bogged down in the details next we're going to be moving from the bottom of the canyon to the top oldest rocks to youngest there's a principle in geology called the principle of superposition which is just a fancy way of saying that rocks form in layers and that those layers are formed by laying down younger rocks on top of older rocks so the youngest rocks in the Grand Canyon will be towards the top while the oldest are at the bottom again we are going to start at the bottom and finally in order to bring some sort of structure to this discussion we're going to talk about these rocks at different scales of geologic time geologic time is broken down into these divisions and subdivisions and more subdivisions and the different breaks between divisions signify major events in Earth's history as evidenced through the fossil record so we're going to start with big divisions and work our way down to smaller divisions talking about layers and groups of layers at different time scales depending on what makes the most sense this will become more clear as we get into it also geologic time is like inaccessibly long and pretty much impossible for our little lizard brain means to truly comprehend so I'm going to be using a handy analogy that the Park Service uses which equates the whole of geologic time with a single year of our time so in this analogy the formation of the Earth would occur on January 1st and our modern day is at the very end of the year to give you an example and probably send you into an existential crisis the period of time we are living through right now is called the Holocene Epoch which started roughly 12 000 years ago and this analogy the Holocene Epoch would have started on December 31st at 11 59 pm all right let's get started so the first and oldest layer of the Grand Canyon we're going to talk about are the Vishnu basement rocks they come from a period of Earth's history known as Precambrian time but more specifically a time period known as the proterrazoic Eon which runs from roughly 2.5 billion to 540 million years ago in our calendar analogy this Eon runs roughly from June 16th through November 19th it covers almost half of the time that Earth has existed this is an Ancient Ancient period of time when you're talking about the very beginnings of the formation of the continents and I'm not talking about the present day locations of the continents I'm talking about the literal formation of the rock that makes up what are today considered continents I told you this time period is ancient we are also going to see the first evidence of oxygen in our atmosphere at this time and life really only exists as very simple single-celled organisms later on in Precambrian time that abundance of oxygen would allow simple multicellular organisms to evolve and at the very end of this time period the first things that we could consider animals will appear the fossil record though is very sparse here because again there just isn't a lot of life to speak of this is the time period when the Vishnu basement rocks are starting to form they are anywhere from 1.6 to 1.8 billion years old yes with a B also by the time these fish new basement rocks are forming Earth has already been around for three billion years these rocks Trace their Origins to the very beginnings of what would become the North American continent and are actually part of an ancient mountain chain see as this mountain chain was forming these rocks were actually pushed and crumpled down deep into the Earth's surface where they were subjected to intense amounts of heat and pressure so much so that they actually changed from volcanic igneous rocks into metamorphic rocks then those mountains over millions of years eroded away leaving these Vishnu basement rocks the primordial guts of those mountains exposed eventually new sediment was deposited on top of the Vishnu basement rocks forming all of the layers we see above them in the Grand Canyon today and which we'll talk about in a minute all right the next layer up on our tour is the Grand Canyon super group it's technically made up of a bunch of smaller layers but we're just going to talk about them all together here believe it or not these rocks still formed during the pro-terozoic Eon during the Precambrian times only they formed more recently about 1.2 billion to 740 million years ago which puts them in that October November time frame in our calendar year analogy this is the time again when there's just not a lot of complex life to speak of we'll start to see the beginnings of multicellular life but the fossil record is also pretty sparse here unlike the Vishnu basement rocks however the rocks of the Grand Canyon supergroup are sedimentary which means they were deposited as sediments in this case by a large sea before being solidified into rocks they are not volcanic like igneous rocks and have not been subjected to high heat and pressure which would have turned them into metamorphic rocks they are sedimentary now there is something peculiar about the Grand Canyon supergroup you might notice that they are tilted see there's another principle in geology called the principle of original horizontality which is just a fancy way of saying that sediments are deposited more or less horizontally and that if they are tilted like the Grand Canyon super group this occurred after they became rocks in this case the Grand Canyon supergroup was subjected to some sort of tectonic activity causing them to be uplifted and become angled now remember that everything up to this point was in that proterozoic Eon that Precambrian time not a lot of life to speak of very little in the fossil record at this point above the Vishnu basement rocks and above the Grand Canyon super group we are going to be dealing with rocks from the Paleozoic Era a whole new classification of geologic time we're going to start to see some more complex life and more things appear in the fossil record which we'll talk about when we get to them but before that as we're traveling up from the bottom of the Grand Canyon as we pass into the Paleozoic Era we're going to pass a line called the Great unconformity in some places in the Grand Canyon one billion years of Earth's history is missing as we cross this line essentially what has happened here is that those 1 billion years have already been eroded away rocks used to be there but were eroded away and then the new rocks the ones we see today were deposited on top of them only they're much younger than the older rocks below them because again the rocks that should fill in that age Gap have already been eroded if we go back to our book analogy this would be like ripping Pages out of the book we can't read those pages and thus we can't understand this part of the story the Grand Canyon is actually filled with unconformities like this places where there's a gap in the geologic record where the story is missing only they aren't as large as this one which is why it's called the great unconformity you'll notice these though as we talk about dates higher up in the canyon all right let's read on okay we've now moved into the Paleozoic Era crossing over the great unconformity all of the Rocks we talk about from here on out will be from this era because of that and because there are more things appearing in the fossil record we can actually further divide geologic time into even smaller units in this case we can break down the Paleozoic Era into smaller subdivisions called periods which will make it easier to understand everything we are about to talk about this first set of Paleozoic rocks we're going to talk about are from the Cambrian Period occurring between 541 and 485 million years ago that's November 19th through 23rd on our annual calendar now the Cambrian Period is really important in the history of Earth because it's where we see something called the Cambrian explosion if you'll recall from the end of the proterozoic Eon we were just starting to see the beginnings of complex multicellular life well here in the Cambrian multicellular Life Starts to rapidly diversify and we start to see things like shelled Marine invertebrates think trilobites sponges brachiopods and even primitive jawless fish it's one of the greatest periods of evolutionary activity in Earth's history this like that there's still no terrestrial life though here in the Cambrian Period life on Earth is concentrated in the oceans and speaking of oceans the oldest layer of Cambrian Rock in the Grand Canyon the tapit Sandstone was formed with the help of an ocean not quite in the ocean like we'll see with some other layers but more of a near-shore Sandy Beach type environment hence the Sandstone this layer is about 525 million years old the thickness of the tapit Sandstone actually varies throughout the length of the Grand Canyon because the ocean was advancing and retreating throughout this time period And Thus more or less deposition would have been occurring depending on how far inland the ocean came okay moving on to the next Cambrian layer the bright angel shale roughly 515 million years old as far as life and fossils go again we're still in the Cambrian Period so there's not much difference in terms of the overall landscape of life on Earth but as its name implies the bright angel shale is made up of well Shale plus some fine-grained Sandstone that's what gives it that pretty greenish purple color it's going to be laid down as that ancient seed continues to advance Inland making this more of a shallow Marine layer than a near shore one this layer is highly erodible and so you'll often see it form nice slopes rather than Cliffs and finally the youngest Cambrian layer in the Grand Canyon is the mauve Limestone m-u-a-v roughly 505 million years old that sea has continued to advance Inland making this a deeper Marine layer hence the Limestone which forms from the shells of dead marine animals all right as we continue our journey up and out of the Grand Canyon the next rocks we come across are going to be from the devonian period which lasted from roughly 419 to 358 million years ago or November 28th through December 3rd on our annual calendar the world during this time is still a marine dominated environment and a great diversity of fish appear at this time we've already had jawless fishes but we now start to see fish with jaws so start to see sharks and the ancestors of what are called today rayfend fishes which are pretty much the fish you're probably picturing in your head right now Cod tuna clownfish I don't know fish but while this version of Earth is dominated by marine life land plants have also arrived to the party and as they continue to reduce their dependence on water for reproduction they begin to develop thicker stems and better ways to move nutrients around leading to the evolution of wood and eventually forests that's right the devonian period is the first place we start to see forests appear in the fossil record we're also going to see things like insects and spiders appear for the first time as well as a little group of animal known as tetrapods which would give rise to all modern terrestrial vertebrates now back in what would become the Grand Canyon there's only one layer of rock from this time period it's known as the temple Butte formation and is roughly 385 million years old the sea is continuing to advance in this area and so the temple Butte formation is again primarily Limestone but it's not a very thick layer as it's mainly seen in Old River channels as the sea Advanced and covered these ancient riverbeds the deposits of the temple Butte formation settled over those beds and deposited the Limestone we see today next up our tour takes us to rocks formed during the Mississippian period which lasted from roughly 358 to 323 million years ago or December 3rd through 6th in our calendar year you may be more familiar with the terminology of the Carboniferous period but here in North America we split up the Carboniferous period into older Mississippian and younger Pennsylvanian periods just because it makes more sense based on the Rock layers found here anyway here in North America everything is pretty much underwater but on land those tetrapods have evolved into the first amphibians and by this time have actually rapidly Diversified thus the Carboniferous which remember includes both the Mississippian and the Pennsylvanian is called the age of amphibians deep collection of life on Earth here is really starting to include some groups we're all familiar with now in terms of the Grand Canyon well two different Rock layers are formed during this time the oldest is the red wall Limestone dating to about 340 million years ago as its name implies this layer is again mostly made of limestone again laid down in a marine environment from the shells of dead sea creatures but we are getting a little more shallow at this time the sea is retreating and we'll see a different composition of rock here because of it now contrary to its name though the red wall Limestone isn't actually red The Rock itself is more of a grayish color but the iron from the layers above it has seeped down and stained those rocks that Rusty red color the younger of the grand Canyon's Mississippian layers is the surprise Canyon formation laid down roughly 320 million years ago this is again a marine layer but again that seat is continuing to get more shallow and we'll see a layer made mostly of shale like the temple Butte formation the surprise Canyon formation was also laid down in old riverbeds and isn't as thick in fact this layer is very rare or to see in the Grand Canyon because it has been heavily and in some places completely eroded as we talked about the second half of the Carboniferous period here in North America is known as the Pennsylvania period And this is the next layer of Grand Canyon rocks that we'll climb through on our way to the top the Pennsylvanian period lasted from roughly 323 to 298 million years ago or December 6th through 8th in our annual calendar unlike the Mississippian period which again saw North America covered mostly in water the Pennsylvanian seized North America dry out a bit and become more terrestrial environment worldwide this is the terrifying time when you would have found dragonflies and cockroaches that were several feet long not inches the world was filled with Lush swampy forests and ferns as tall as trees on the animal front we are still in the age of amphibians but those amphibians have started to figure out how to decouple themselves from reproducing in Water by developing the amniotic egg which eventually gives rise to the evolution of reptiles during this time and as far as Grand Canyon rocks go one layer formed during this time period although it's more like a couple of layers and its formation actually dips into the Permian period a bit but we'll talk about it here that layer is known as the supine group dating from roughly 315 to 285 million years ago this layer is really made up of four separate layers because they all had different depositional environments as the sea continued to advance and Retreat you'll find limestones shales and sandstones here all deposited in Marine estrogant and terrestrial environments it's a diverse layer and really goes to show us how different this part of the world has looked at different points in its history okay we have reached the final time period in which the rocks of the Grand Canyon were deposited it is known as the Permian period and lasted from 298 to 251 million years ago or December 8th through December 12th on our annual calendar this is the world of Pangea that most famous of supercontinence Pangea was surrounded by a world ocean known as panthalasa which that name just terrifies me for some reason the world is hot and dry and that amniotic egg is really working wonders as our ancient ancestors continue to rely less and less on water for reproduction and become the dominant form of terrestrial life this is the time period where we see the lineages that gave rise to the dinosaurs first appear also at the end of the Permian period the most devastating mass extinction event the world has ever known occurs wiping out 90 of all life on planet Earth but hey let's talk about rocks there are four layers of the Grand Canyon deposited during this time the oldest and bottom most is the hermit formation 280 million years old it contains mostly sandstone and siltstone and was formed as part of a dry broad coastal plain it's pretty erodible so you'll recognize it as a slopey layer and not a Cliffy layer it's also pumped full of iron dioxide giving it that deep red Rusty color above that is the Coconino Sandstone 275 million years old it's a very conspicuous white layer near the top of the canyon it's dominated by of course Sandstone because when this layer was deposited the area was a giant massive Dune field just one big old pile of sand in which winds blew in from the north and depos did a bunch of sand that eventually hardened to rocks which we now call sandstone and which is now part of the Grand Canyon all right moving on above that is the Toro weep formation 273 million years old back to a marine environment for this one but probably pretty shallow and advancing and retreating several times over the course of this layer's deposition that's why I'll see all kinds of rocks here from sandstone to Limestone to gypsum and a bunch more and then finally we have reached the top the layer we stand on when we visit the Grand Canyon when we peer out over its Rim into this vast Chasm of rock and time this is the layer we stand on it's called the Kaibab formation and it was formed 270 million years ago this land is once again covered by an ocean meaning the Kaibab formation is dominated by Limestone but think about that for a minute there you are standing on top of the Grand Canyon Standing On Top of 270 million years of Earth's history Standing On Top of rocks that were formed when Pangea was still a thing when a vast ocean enclosed almost the entire planet when the world was so incredibly different from today that it's almost impossible for us to comprehend and then imagine leaving that room and making the return Journey back down to the bottom of the Grand Canyon passing through layer upon layer of Earth diving deeper and deeper into the annals of geologic history revealing the creatures and climates and conditions of that prehistoric book you can now read this book you can now look into the past and see what was happening on this planet millions and billions of years ago and how that influenced what we see today you can touch those things you can feel them you can understand this story the story of Earth I think that's pretty cool and I think it's even cooler that that story that book is protected as one of the world's Premier national parks you want to hear more stories about national parks and protected areas around the world don't forget to subscribe to the channel and hit the little bell so you don't miss an episode also I don't want to toot my own horn but I think my patreon is a pretty cool place to hang out I run a book club over there I do amas behind the scenes videos and I have a Discord truly this operation national park diaries every video I make is fan funded I stand on the shoulders of a tremendous community and my patrons are a big part of that so huge shout out to them if that sounds like something you'd be interested in supporting you can head over to patreon.com national park diaries thank you for watching goodbye

Channel: National Park Diaries

Views: 65,655

Keywords: grand canyon, grand canyon national park, grand canyon discovery, the grand canyon, grand canyon mystery, mystery of the grand canyon, history of the grand canyon, secrets of the grand canyon, grand canyon explained, new grand canyon discoveries, grand canyon caves, things to do in grand canyon, amazing grand canyon discoveries, 2022 grand canyon, grand canyon is missing, grand canyon facts, grand canyon giants, grand canyon ancient egypt, grand canyon skywalk

Id: 7lXtUeQBKHE

Length: 26min 15sec (1575 seconds)

Published: Mon Apr 17 2023