Supercontinents and the Pacific Northwest

okay so let's get started so tonight we're talking about supercontinents have you heard of such a thing a supercontinent you've maybe heard of Pangaea is that a name that rings a bell yeah we'll talk about Pangaea but it's not the main focus tonight we're going to go way back into history we're gonna go back hundreds and hundreds of millions of years before Pangaea to earlier supercontinent oh the room got quiet suddenly like what really yes there's even names for these earlier supercontinents than Pangaea and then before our mind is just going to blow up and just a burn and smoke and everything and we can't handle all of that we'll take a break and we'll go to the Pacific Northwest because this is a geology lecture that focuses on rocks of the Pacific Northwest and we're going to look for some rocks that can tell us something about that cycle of super continents we've got to find some really old rocks to do that but we can find them and will feature the belt series tonight for those that know geology very well that's our game plan 30 minutes of chalkboard 30 minutes of visuals and hopefully we'll feeling a sense of accomplishment by the time we're done with this thing are you ready to go okay let's do it wonderful so this is a black chalkboard let's pretend that it's a world map a world map from your freedom your youth in front of your grade school classroom can you picture a world map in your mind how many continents are on that world map seven continents that's right and there's a handful of oceans between North America and Africa the Atlantic Ocean the Pacific Ocean okay fine good are you aware that if we pull down a different world map for 200 million years ago it will look very different in fact there'll be one continent on that world map for 200 million years ago and one ocean and that one continent was a big big continent in fact it was a supercontinent called Pangea let's write it out Pangea PA n Gea that's one way to spell it and that's how we're gonna spell it tonight 200 million years again we're gonna be working in hundreds of millions of years even thousands of millions of years tonight more than a billion years so one way to view Pangaea is okay it was a supercontinent and in the last 200 million years Pangaea has been breaking up it broke into seven pieces our seven continents and those continents continue to drift away from each other there was no Atlantic Ocean during Pangaea you could have walked directly from New York to Morocco in Africa and in the last 200 million years the Atlantic Ocean has continued to grow in width and the Pacific Ocean has been shrinking in width four inches a year the Atlantic Ocean grows four inches wider every year that's pretty fast we have GPS measurements to document that Christopher Columbus did not have as far to travel as we do now insert laugh track okay great so if we open Pangaea if we open the Atlantic Ocean as we break up Pangaea we're actually closing the Pacific and so one way to view Pangaea breaking up is we're heading for the next supercontinent we're closing the Pacific and opening the Atlantic now if you're aware of Pangaea and I think most of you are maybe you assume that Pangaea was the way earth was given to us like Pangaea was the original configuration and there's just simply been this breakup I think a lot of people think that without thinking about it a whole lot but how old is the earth this is a science lecture right how old is the earth it's four thousand six hundred million years old the earth is 4.6 billion and I want to stay in millions tonight I don't want to go back and forth between millions and billions okay so four thousand six hundred million so there's a lot of time before Pangaea that's the next concept there was a completely different geography that's almost unrecognizable to us before Pangaea therefore there was a time that we assembled Pangaea yes like a jigsaw puzzle that's the common analogy put the pieces of the puzzle together so Pangaea supercontinent was together for 100 million years that's worth thinking about for a second that's a long time dinosaurs were alive during when Pangaea was together and dinosaurs were alive when Pangaea started to break apart a hundred million years for one continent and one ocean on planet Earth but I got room and I got a piece of chalk and I'm gonna write down two other names of two other super continents that we now know about that predate Pangaea let's get to it Road inia Columbia and you're like wait a minute I like geology I read about geology all the time I've never heard about either of those well they're pretty new the proposal for the supercontinent Rodinia got into scientific papers in the early 1990s that's not that long ago Pangaea was proposed by Alfred Wegener more than a hundred years ago and the supercontinent of Colombia sometimes called nuna came out in the last 15 years so this is pretty new information so don't feel too bad if you haven't heard about it I knew very little about these two super continents about a week ago I've been cramming I put crab whoa all right I got a laptop I got the internet I can find these scientific papers that got back from Spring Break I'm like oh my god I got a lot of work to do on this lecture and I started emailing these authors these researchers in addition to reading their papers and I've got some good stuff for you I've got some good stuff for you about Rodinia and column I can't hold it I got to say the first major message the Pacific Northwest have rocks that are all about these two super continents and not Pangaea Pangaea is too new for us too young for us so Rodinia was assembled more than a billion years ago 1100 million years ago is more than a billion right and 750 million years ago is when Rodinia started to break apart let me finish this blackboard here columbia 1800 to 1400 there's a supercontinent cycle assemble keep together for hundreds of millions of years break apart we live in a ball if we break apart a supercontinent they're going to get together somewhere at some time next supercontinent break that apart next supercontinent you get it and just like all kinds of history the further back in time we go the less we know we know by far the most about Pangaea and very little about Columbia but enough to include it in this lecture and I do feel for the sense of completeness that there are earlier than this supercontinent ideas but those are really scraps it's not worth it in my opinion comfortable head spinning too much time can't handle it looking for the nearest exit alright maybe I figured that was the case so I'm gonna keep this on the stage up here as a reminder it's not going to change the rest of tonight and now I'm going to work with these two guys for the next 20 minutes or so and try to use northwest geology to somehow eventually plug back in okay so let's switch things up I think we need a break from this let me tell you a story and the story takes place in a national park that's right there Glacier National Park so the story involves my favorite subject me it was the summer of 1983 it was the summer that I was turning 21 years old I was going to school in Wisconsin that's where I'm from Madison three years in college no direction no major couldn't find anything that interested me ran out of money basically took a train from Madison Wisconsin to Glacier National Park in June of 1983 I mean how old am i I'm taking the train for goodness sake it's not that far I didn't have a car at the time great my job my summer job was to work at Lake McDonald Lodge on the west side of Glacier Park many of you have been there there's the lodge there's the general store there used to be a little gas station and my job was to pump gas and to sell souvenirs at the general store with a bunch of other college kids who were there for the summer from all across the country I'm telling you this story because it was my first time living in the West it was my first time hiking in the mountains and it's the summer that I discovered geology I had no interest in geology before that summer but I did these day hikes they did these visits to these places that really surprised me first of all the scenery was beautiful we all have that experience but there was one particular day hike I want to tell you about as quickly as I can I've got photos I'll show you from that actual hike in 1983 we're going into the archives tonight so Craig and Webb and Bruce and I jumped in Craig's car we drove from Lake McDonald up to going-to-the-sun highway to Logan's pass many of you have been there we parked right that big parking lot early in the morning we hiked north on the Highline trail pretty easy walking and then at some point Craig said we're going to the top of Mount Gould are you ready Mount Gould is the very top of the Continental Divide in Glacier Park it's the top of the garden wall and we're all in our early 20s do you remember the days where you could just walk up a mountain with your hands in your pockets essentially I missed those days so it was two o'clock in the afternoon we're on top of Mount Gould we're up high enough that it's a bluebird day and we can see out to the plains of Montana some of you have experienced that you're up that high you can look down on Grinnell glacier down on many glacier hotel and I was a greenhorn I was literally wearing my farm boots literally my farm boots from Wisconsin all these other guys had all the hiking gear but I was I was new to the whole scene and we had lunch I had my little PB&J a little packet of skittles I remember and I was sitting on this maroon rock up there in the top of Mount Gould and the other three guys were about 15 yards away from me sitting on a different rock and at some point Craig broke the silence and said hey you are so out of it why did you pick that rock to sit on isn't it uncomfortable and I'm like I don't know he said you're sitting on a bunch of those ripples have you noticed aren't you uncomfortable and it's true I was sitting on this slab of maroon rock that had these beautiful symmetrical petrified ripples on the surface of the rock and I was like oh yeah I had these like red stripes on the back of my bottom and my thighs and then Craig said do you know how those ripples formed you know kind of a show-off you way this is 1983 you can't just pull out your phone and like double check with the guys saying you know it was like this used to be a beach I took geology 101 at Oregon State University and I learned that these ripples formed at the beach and I'm like that that's not good and he kept talking about this beach thing in the coastline this was the old coastline all the other guys were like nodding their heads and I'm like I don't believe you okay I'll finish the story Craig was right those rocks are Precambrian rocks that clearly formed at the old coastline of North America here and those rocks are all through this area let me draw a line for you this is a very clear line on that map of the Pacific Northwest and that line is the true coast of the Pacific Northwest or the west coast of North America for hundreds of millions of years and Spokane is right here that you can see that Gold Dot so pretty much everything between Spokane and Glacier Park and those rocks continued to the south down to Vegas and even into Mexico and north up through Canada these are all beach rocks these are all rocks that are muds and sands and they are called at least in the United States the belt series or the belt supergroup it's where the Rockies are today but this predates the Rocky Mountains that was my confusion eating my skittles I'm like I don't get it these are the mountains what are you talking about the beach for you can go from a beach scene to a mountain scene if you have enough time and that's what we're talking about here collectively these layers of rock that were originally sedimentary rock and are now metamorphic rock the belt series located on that map they're Glacier Park Spokane Steptoe Butte cava Loyola Medical Lake Libby Bonners Ferry take your pick all of those plots have belt rocks located there they're beach rocks they're Precambrian aged rocks in total that that cake is five miles thick 25,000 feet worth of sedimentary rock deposited at the coastline of North America we have dates now dates for the belt fifteen hundred million to fourteen hundred million seriously old during that time we deposited all of those beach rocks now originally it was sand at the beach and mud at the beach those ripples I was sitting on beneath the patch of Skittles was a tidal zone was a muddy zone you've been to the beach the coast of Washington has a lot of mud right and you have drying mud that forms cracks you have the ripples in certain places off the coast of Australia you can get stromatolites these big mounds of blue-green algae stromatolites that are fossilized in this mud and sand we all know sand is at the coastline at the beach but originally the sand got buried into sandstone and the sandstone got heated up and pressurized to become quartzite and the mud got buried to become a sedimentary rock called shale and the shale got buried to become a metamorphic rock called slate and the slate sometimes turned into argillite so what are the belt rocks today rocks of this age represented an old coastline interbedded layers of quartzite sand argillite skort sites and argue lights but we don't care that they're metamorphic today we care that they were originally deposits at the beach the energy in the room is great and we're now to the juicy part we haven't even gotten to the good stuff yet now this is what I've been teaching for a long time and I would not only draw what I just drew here for you but then I would say to my students over the last 25 years where do you think all that sand came from well it's the coast isn't it aren't we going to assume there were rivers draining North America at the time I hope it's clear to you Washington doesn't exist yet Ellensburg doesn't exist yet Oregon doesn't because this is deep ocean this is open ocean but we're talking about all this sediment accumulating at that shoreline the belt and we're assuming that the rivers are flowing from east to west and that's true a lot of the sediment in the belt came from the East from the interior of Old North America and drained to the coast you ready I'm leaving stuff I've taught forever to stuff I've never taught stuff that I've learned in the last ten days it's good here we go because remember the gimmick of the lecture I'm going to somehow say the belt has something to do with this this is just a coastline and yet I'm saying there are times when all the continents of the world are hooked together some of you are a few steps ahead of me possibly especially when I say this for years it was clear that when you carefully study the sand in the belt not all of it came from the east there were paleo current indicators details written in the court sites and the sand stones to say a bunch of the sand in this belt came from the West now let's pause and think about that for a second is that possible you can't have a river come out of the deep ocean and come on to land and bring sand there's a lot of sand that looked like it came from the West next point there's a new technique we talked about last year and we're talking about again right now a mineral called zircon zircon is a very durable mineral many of the sand grains are zircons and as a geologist now you can go out and collect sand grains from the belt analyze the age and the chemistry and the rock type of those sand grains and find a source find a place where those zircon grains came from we couldn't do that before are you ready both the Paleo current indicators in a bunch of the belt especially in the lower belt and the zircon say that a substantial amount of this five miles worth of sand is somebody else's sand is exotic sand is not sand from North America there's not a match to interior North America there's a match where somebody else's continent now hold on when we have a supercontinent we have continents coming together and soldering together for a while before they then decide to split up Don Winston who spent most of his career on the belt he's a geologist in Montana would have maps and during belt time would say even in some scientific papers Don Winston would say continent X continent X I don't know what continent it was but it was some somebody was here somebody was docked right at Spokane and then took off at some point but the concept is we need continent X because we clearly have a continent with rivers flowing from west to east and depositing the sand into the belt from a different source let's pause again and then we'll reveal continent X look at the age of the belt does this work age-wise with Pangaea of course it doesn't you've already done this does it work well we'll throw dénia doesn't work well throw Denia as well look at these dates fifteen hundred million to fourteen hundred million that's the last 100 million years of super-continent Colombian when all the continents of the world were together when North America was connected to Australia continent X was Australia now let's draw that and possibly turn your telephones off at the same time can we multiply can we multitask these new inventions called cell phones with ringers all right let's do a cross-section of this same thing let's put Spokane here let's put the belt at the coast of North America and yes I revealed it verbally let's do it this way and I have to put an asterisk behind Australia I'll tell you why in just a second ah stray oh yeah you could have walked if you have relatives in Australia you could have walked from northern Idaho to Australia there was no Pacific Ocean at this time now what's the evidence the evidence is you can study the zircons in the belt and you can find Precambrian rock in the core of Australia that's a match that's a match age chemistry everything else same thing here so on this sketch I can do this it even gets better there are some grains of ours that went the other way but I have to put an asterisk next to Australia and here's why a majority its 2019 is it not there's a majority of geologists in 2019 that say it was definitely Australia I've written my scientific paper and I've got all this evidence to match the belt of the Pacific Northwest with the belt of Australia and some old kraton on North America and Australia as well but from this point forward in our little lecture I'm going to do this every time I say Australia okay this means a stir it because there are still some holdouts there are still some geologists who say it was not Australia it was Siberia another group says it was not Australia it was Antarctica next door Park to John Stockton's house in Spokane even another group saying it was not either those it was a piece of south china Precambrian crate end of south china so there's a chance all four of those are still going to be in the literature for a while but there's enough people saying Australia and the visuals all have showing these world maps many of them will have Australia next door during super continent Columbia I don't know how you feel but that was the big moment tonight now I'm telling you how to react that's cheap so last time I checked Australia is not here anymore it took off at some point and we have a date for that for sure everybody agrees that continent acts most likely Australia rifted away began to break away from the Pacific Northwest 750 million years ago the evidence for that is something called the Windermere group and specifically the evidence for that is there are basalts that start showing up the salts that have now been metamorphosed into rocks called green stones but if they originally basalts and anytime you have a continent rifting away from another continent like north america rifting away from Africa during pangaea's breakups you develop ocean crust in between those rifting continents you create ocean crust in between these rifting continents so the basalts now green stones of the Windermere group is the basalt that formed as Australia rifted away from old North America never to come back or will it will we reconvene and be reunited with Australia at some point in the future in the next supercontinent to come the last thing I want to do is very quickly on the chalkboard and then we will switch to the visuals because I've got lots of good stuff for you there Australia is gone but I feel we need to make Washington if this is a lecture in Ellensburg Washington in the Morgan auditorium we got to make this state somehow don't we we can't just leave deep ocean here at least I don't think we can and so if we jump way up here to the breakup of Pangaea and North America is starting to move west as Pangaea breaks apart let's do that North America is moving west with the breakup of Pangaea so there goes Africa heading out the other way and if this is new to you you'll see some maps what city is here Spokane this line is clearly where Australia rifted away and that old rift has been there for a long time it's a very sharp boundary geologists call it the strontium 706 line simply meaning that there's certain chemical signatures in the magma is coming up through this kraton material and very different chemistry's strontium differences with the magma is coming up in this other stuff so how are we going to build Washington in the last 200 million years many of you know this last year we did a lecture on exotic terrains but I want to revisit the main concept which is we had a huge ocean plate called the Farallon plate that was coming at us and subducting beneath us this is ocean now and we make Washington by receiving gifts from the Farallon plate huge gumdrops huge exotic terrains of different origins that are riding on this conveyor belt and as the Farallon plate continues to come at us we build Washington piece by piece and eventually we build the entire state of Washington the last terrain to come in made the Olympic Peninsula and we'll have a couple vision yuria this is a big room now I can't talk one-on-one with you right so there's a whole scene there's a whole drama just in the last 200 million years but this lecture is predating everything we've done in this series everything we're talking about here the Ice Age floods the flood basalts the Cascades the bridge of the gods landslides everything it's wall right up here this is the first lecture we're brave enough to go this back this far back in our history and certainly there will be new data coming about those old super continents this is the moment to say to your neighbor isn't this interesting I love this and why you say that we're going to get this screen going in the projector ok give us just a second thank you ok the chalkboards do a decent job but I think we need more I think we need more professional imagery and some animations and a few other things to make this work so let's go ahead and take some photos etc we've got some really wonderful footage of Glacier National Park you can see the layering of the bedrock here that's the belt these are the beach rocks between fifteen hundred and fourteen hundred million years the glaciers themselves have dug so well recently to reveal all these cliffs otherwise we wouldn't see many of these rock layers but this is the place that it's quite easy to be introduced to the belt series they're right there in front of your face they're on every hike that you do in Glacier National Park coastal rocks and now you're looking at this in a different way now oh my god there's grains from Austria yeah in the picture now let's zero in on some of the structures that are in the shales and the sands that are now metamorphic rocks to convince ourselves that this Beach story really is true look at this these are mud cracks in a tidal mud flat from more than fourteen hundred million years ago isn't that unbelievable this is so far far back in time we have no major fossils to bio turbit to screw up all these very delicate features so the amount of preservation in these rocks that are more than a billion years old is absolutely staggering these are the stromatolites we're still in Glacier National Park now these big mounds of blue-green algae think the Great Barrier Reef off the coast of Australia if you like oh that's ironic off the coast of Australia it's so rare to see fossilized mounds of algae number one but to find them in this old setting is truly outstanding now the picture on the right is the best I have for you to show some of these current indicators can you see there's kind of some Nike swooshes and some of this stuff so geologists can study the arrangement of the sand grains and say something about the direction that the river was flowing and here are the uncomfortable Rock to sit on the ones that have these symmetrical ripples in the slate that used to be mud so these Maroons and these greens in these purples if you've been to Glacier Park you know exactly what I'm talking about and those are the rocks that we're featuring tonight from supercontinent Columbia this is a slab that's on display in our geology building here in town and just running your hands over those ripples is like being at the beach 1,500 million years ago now let's leave the high country where the belt is best exposed the belt series and let's go down to Lake McDonald Lake McDonald famous for its beautiful brightly colored rocks in the bottom of the lake we know those rocks now those are broken off pieces of the beach belt series all about we're going into the archives and there's the general store it still pretty much looks like this look at the size of these cars by the way in 1983 and the huge Coke machine so I'd be walking back and forth when a car would pull up to the pump I'd walk out and pump their gas and then go back and sell a rubber tomahawks and all sorts of stuff and this is the morning of that hike that I was telling you about the very morning of our group of four heading up to mount Gould Craig was the leader Craig was the guy telling me about the beach up on top and after our Beach conversation I took the photo here because I was had a frown on my face probably I still didn't understand why there was a beach in the mountains but you can see how high we were and can you imagine the effect of a summer like this from a kid from the farm in Wisconsin had never experienced anything like it I still have the book that I read the rest of the summer that we sold I never bought it I just kind of borrowed it and I would read and reread that geology that going-to-the-sun highway out in front so when I took a break from working in the store I'd come out here and sit in front and I'd reread that one little geology book I've got it right up here on the stage and one of my jobs with a co-worker was to bring this statue out every morning and then bring them back in so nobody would rip it off and I hope that guy still there with this cigar he was the last time I visited in 2010 so this book written in 1983 just a few months before I worked there was the reason that I got into geology there were other things to learn that summer we don't need to go into that kids from all over the country and many of us working in Glacier Park had music backgrounds and so for some somehow I got to be the little master of ceremonies like serenading the the the large people so every Wednesday night we'd have this little group sing along with the guitars and everything okay back to the geology so look carefully at this map we've got Idaho and Montana but we got the old coastline that the belt is telling us about that the belt rocks are telling us about and here is a more specific map showing the exact locations of where we can find belt rocks notice we are getting into northeastern Washington Spokane is about here right so we've got the corner of our state and all the way down even into the Lemhi mountains of central Idaho have many of these grains that have been studied very carefully by Paul link and others I went on a field trip a couple of summers ago just along Interstate 90 near Coeur d'Alene and Andy buddington here's in the blue shirt and many of these photos are from Edna buddington who teaches geology Spokane community college and he was a great help in putting this lecture together he has studied the belt academically he worked in the silver mines right out of school as a geologist and so he knows the Wallace area quite well and so there's a tie with or as well and the belt but anyway this is just the fridge row this is the old roads right next to i-90 basically buy the best steaks in the world that wolf what is that Wolf Creek Inn or something like that an amazing amazing place here's Eric Chaney from the University of Washington leading us on a small geology group and they kept talking about rodinia and I didn't know what they were talking about two years ago and the breakup of road inia now we know how to rodinia and supercontinent Columbia fit into this story so these if you're a geologist in the room these are all familiar looking photos you go out you stop you put up a map on the side of the van and you talk and you talk and then you go point it some more rocks these are all the belt rocks that we were featuring tonight so it's the same rocks that we saw in Glacier Park but right along the freeway right there available easy to stop and look at if you're very interested more photos from Andy now we're into Northeast Washington and northern Idaho we see more of the ripples we see more of the petrified ripples look at how fresh they look even though they're so old mud cracks have different looks some of them are truly cracks some of the cracks have been filled with replacement minerals and the stromatolites are found in other places in the belt besides Glacier Park you've got the point now we're finding these features we're finding this consistent Beach story for a long time even Steptoe Butte which many of us know as a landmark south of Spokane and north of Pullman is made out of quartzite it's part of the belt it's a it's an island of belt surrounding by the more famous geology of the Palouse so our eyes are drawn to the Ice Age Palouse and the flood basalts that are beneath the rolling hills but the island itself the mountain itself is from the beach time from Precambrian days so not to talk too much about myself tonight but when I finally went back to Wisconsin and took geology 101 after that summer in Glacier I then got a geology degree it was time to go to grad school and I said well I'm gonna go back out there I'm gonna go study and I haven't really left the Northwest since then a photo from leaving the tearful goodbye with mom and dad and my brand-new car for the first time a Toyota Tercel with no air and no radio and no floor mats and my all of my all of my belongings hitting the road and getting out to Teton park and eventually into the Snake River plain of Idaho I went to Idaho State University in Pocatello it's a great place for me learned an amazing amount and started teaching there as well great if I had gone to graduate school 200 million years ago however there was no reason for me to leave Wisconsin and go to Idaho there were no mountains at that time the mountains were in South Carolina because there was no Atlantic Ocean and Pangaea was in place that was the dominant Himalayan like mountain range at the time and when we break up Pangaea we take that mountain range which used to be connected to Africa and northern Europe and we split it in half and the Appalachians have been slowly withering away in the last 200 million years so this familiar world map has half the mountain range from Pangaea assembly here and the other half of the mountain range from Pangaea assembly there 300 million year old mountain range mountain and ocean developing in the last 200 million years so here's the first of our mind-blowing Maps if you haven't seen these before this is the supercontinent of pangaea notice spokane on the coast we had like where's Australia I thought that was the big mention tonight it's not gonna be on this one is it we needed a much older supercontinent to talk about the Australia story I love this taking today's countries and placing them on Pangaea let's zoom in on that so you could go from New York to Morocco you could go from Charleston South Carolina to Mauritania you could go from the coast of Florida to Senegal amazing Pangaea our most recent supercontinent now I'm gonna drive here here's North America 200 million years ago I'm getting us to that's what's familiar now let's go back let's close the Atlantic Ocean oh you like this there's murmuring okay this is from Christopher Cote so there's many of these on YouTube if you look up Christopher Scotty's YouTube channel we're gonna do more of that in a bit now this is a more cartoonish version of the same thing I just showed you and I don't have to control this when it goes pretty quickly it's the same idea we're breaking up our most recent supercontinent and there's all sorts of things we could talk about but we don't have time now it's important to notice that when we take two continents and start inching them closer and closer together we've got to get rid of the ocean crust that's between them we need to subduction crust so when people talk about quote/unquote continental drift they fail to factor in the fact that the ocean crust is moving along with the continents is something we call tectonic plates so here's India approaching Asia and not stopping once it kisses Asia and eventually forms the Himalayas that we know and love so we need to realize that ocean basins need to be destroyed as we do that so here between US and Africa is this wonderful mountain range the biggest mountain range on the planet called the mid-atlantic ridge made out of basalt that has formed somehow in the last 200 million years mid-atlantic ridge it has a beautiful pattern just like the coastlines of the Americas and Europe and Africa we didn't know about the mid-atlantic ridge until after World War two but we now know that that is the reason that we let me say it differently we now have good evidence on the ocean floors that this seafloor spreading and seafloor creation is a real thing have you seen this map before these colors are the ages of the ocean floor red is really young and as we get to oranges and greens and blues we go back 200 million years so this was a huge surprise why do you have these AIDS patterns that are perfect mirror images of each other in both the Atlantic and the Pacific that led to this model which we now fully accept today in the middle of the oceans we create crust and we make a new batch of crust crack it in half sand half with North America and half with the African plate and continue and the continents are drifting away from them each other as we create all this crust in between it's an amazing collection of data from the oceans that tie with the continents so the specific Raisa seafloor spreading the Pacific is actually drifting spreading faster than the mid-atlantic ridge but both are active and both are part of the drifting continent story plate tectonics fully embraced by science continental drift partially embraced because during alfred wegener x' time he was trying to convince people that continents were somehow moving through old dead ocean crust and we now know better the map that we know well but now let's go to a map we don't know well this is outside the copy maker in our building I look at this every day when I come out of the Xerox room and I'm like I got to do a lecture on that that's such a great display that Walter zaleka created for us in our new building a couple years ago what does it show it shows the old coastline do you remember here's Montana Idaho Washington there's John Stockton's house in Spokane there's the old coastline where Australia broke away at the end of supercontinent Rodinia there's that coastline today now we're only going to look at a few of these because their mind blowers but I'm going to slow down and try to give you a chance to focus on this this is the best arrangement that we currently have for the old geography of Rodinia not Pangaea the supercontinent before where are we there's Old North America there's the belt of Montana and northern northeastern Washington and here's the belt continuing on Africa and remember we said 750 million years ago is when we started getting Australia to rift away from us so I presented it in a nice east-west sense right but we've got to throw in some other factors here so you'll see slightly different versions of this map for rodinia but this is a fair assessment this is supercontinent Columbia the one older yet the one that at the bottom of the chalkboard and you're like oh god what are we looking at well I we're looking at a supercontinent fine again lorenzi ax is the name we have for old North America can I help you that dot is the belt and you're like wait a minute that that's the belt North America is standing on its head Mexico is up here Canada is down here and this reconstruction of supercontinent Colombia has South China as opposed to Australia I knew this would happen the energy has changed the hands are like I give up I can't know what I don't I lost it I lost it I lost it I knew that was going to happen so we're not going to dwell on it but this is easier to picture I'm not underselling you now it's just too much it's just too much too much but this is a good representation of 750 million years ago when Australia drifts away from Montana Idaho cetera we're going to try this again now this guy's goatees Christopher Scott East is world famous in geology circles he's even got an animation going back looking we're back to earlier supercontinent days and there's lots of error here but there's enough to think that we can do something with it I'm gonna try this I think I only want you to notice one thing here is North America Canada US Mexico and here's our rift here's what Australia is going to rift away at 750 million years ago you ready and okay now if you're a great map reader Scottie's has Antarctica instead of Australia next to us this is Australia that's Antarctica this is Montana that's Canada so you can see there's variations just from animation to animation he's got another one is it worth it I don't know enough to just blow us over okay great so I don't want to show many more of these but our assumption that North America always is nice and tidy and Canada's up north and Mexico's down even that is a spinning orb and the evidence exists for all of that as well which I don't understand very well that's enough of these that's enough of these that's enough of these oh this guy Hoffman this gives you an idea of how you can try to make a case for a certain continent Hoffman's and Australia guy and he says here's the belt in yellow there's a belt like basin in Central Australia another belt in Central Australia here's Antarctica down here he's even taking some of the another part of Old North America and finding it scraps of Australia so it's a game of positioning old continents and configuring them just right to match up certain kinds of geology here's a more recent Rodinia story same idea Precambrian rocks of the Appalachians follow them through this portion of Australia and even a younger thing during the rifting here's Australia rifting away from us as it should 750 million years ago and some basalts some neoproterozoic basins I guess they're Basin sorry but we've got the same idea so it's not just the shapes of the continents as my point it's using some Precambrian geology in there as well oh my god we got this one too you want to really get depressed this is the last two billion years of time and I'll point out this is us that's North America and presumably that's the Montana coast right there so I think these will change over the next 20 years as we get more and more data but I'm going to stick with this until we get something that looks familiar we're not even - a billion years ago yet there's a billion and you're like please something I can record please please where do I fit in they did a nice job should ended the lecture right there okay couple more so you've got headlines like these and I never really understood how to make sense of the headlines because I didn't have that timeline that we had on the black chalkboard I needed that personally to know where to plug some of these headlines in I know I'm a little closer to that and maybe you are too we've already seen that so in the lab we're going to finish where we started talking about Pangaea breaking apart Pangaea and making the rock of Washington with a couple new ideas before we quit here's Spokane here's all the crust that has been added to the west coast of old North America since the breakup of Pangaea those exotic terrains are completely different kinds of rocks with completely different stories of their own that's a whole nother lecture that we tried last winter that was a tough lecture to put together all these scraps of land these exotic terrains have their own story in their own origin if you remember the lecture from last year the main message was a bunch of those terrains were actually added in Mexico and then got shifted 2,000 miles to the north between 80 and 50 million years ago again this is all crazy stuff happening after Pangaea breaks apart and yes we made the point that there's growing evidence that our beloved Mount Stewart north of town was originally in Mexico are you deeply offended by this so looking at this map this is all a very new part of our continent the youngest and newest arrival and the last arrival is the Olympic Peninsula before the rock of the Olympic Peninsula was added the West Coast was a tie five so that's another way to look at this we tonight have been looking at all the evidence for the coast of North America over here at Spokane right that was most of tonight but the coast starts jumping west as we keep adding crust to the western edge of North America all of this basalt that runs from the northern edge of the Olympic Peninsula makes up the hurricane ridge above Port Angeles swings through here by Hood Canal the Willapa hills down by Olympia that's all fifty five million year old basalt that originated offshore a couple years ago we talked about Silesia a huge chocolate gumdrop out in the ocean and that oats that that's the last of the exotic terrains to add to the west coast here at our latitude today we have the Juan de Fuca plate subducting which is a remnant of the Farallon but the point is the age of a huge ocean plate coming at us is about done and our West Coast is going through major changes right now in the last 20 million years we're realizing it now that much of the geology is changing I'll give you a couple of examples and then we'll quit when we did have that big ocean plate coming at us it's abducted and fuelled volcanoes we still have the Cascades so we still have a little bit of that left but we better enjoy the Cascades while we've got them because they're not going to be with us for much longer I'm serious and that's because this ocean crust coming at us is about to quit and it's about to quit because we're about to cross as North Americans over the East Pacific Rise you can see these Pacific Rise today off the coast of South America but we have crossed a majority of these Pacific Rise already and only one little piece of these specific rise is still off the coast of the Pacific Northwest when we finish the job of crossing this little spreading Center like California has cry the spreading Center our volcanoes will stop the volcanoes will stop and the volcanoes will not only stop like they did in Eastern California they're going to physically go away and the underground magma chamber rock is now up in the mountains I'm talking about the Sierra Nevada mountains of California today there used to be Mount Rainier volcanoes in Eastern California but they have gone through this crazy transformation and all this magma chamber rock this granite like stuff is now along the John Muir Trail and in Yosemite National Park I'm saying this is the future of our Cascades better or worse I don't know safer probably no big huge volcanic eruptions ten million years from now this is the scene that will begin because we will have completed the job of crossing the last little piece of the spreading Center known as the East Pacific Rise but that's not the main thrust of tonight the main thrust of tonight is this beautiful National Park with the spectacular looking rocks and the rocks with enough details to tell us stories about super continents from long ago including our friend the most recent supercontinent pangaea thanks for coming tonight everybody sure you'll appreciate it thank you much thank you we'll see you next week you

Channel: Central Washington University

Views: 74,608

Rating: 4.9095259 out of 5

Keywords: supercontinent, Pangea, Belt Supergroup, Precambrian, Rodinia, Glacier National Park, Montana

Id: cg69QbPxHsA

Length: 56min 32sec (3392 seconds)

Published: Thu Apr 11 2019

Reddit Comments

[u/OrangeJuiceAlibi]

It's that damn Panama canal, letting all the water leak out!

[u/ReasonReader]

On the way to the assembly of the next supercontinent.

[u/a070]

I know another thing that grows 4 inches and shrinks, nothing special tbh