okay now the action happens where these plates interact where they meet we call those plate boundaries and there are literally three types of plate boundaries and we're going to go through each one of them and they create different features on the surface of the Earth so one is a so-called divergent plate boundary um another one is a convergent plate boundary and the third one is a transform plate boundary they all look a little different and let me explain what they doing here so my diverging plate boundary is where two plates are pulling apart now do we create a big gap in the valley at first maybe but molten material moves in and often seals that crack up again but there's a lot of activity now you can imagine what happens when you crack a slab of rock not just you know a little stone that you crack open with a hammer but a crack appears along a whole plate that would create some phenomenal stresses and these cracking of rocks must leave some things we can feel see or measure we call those usually earthquakes and they're generated when we when we crack the big system of these plates so a diverging plate boundary we're pulling plates apart a converging plate boundary is where two plates literally slam together into each other now when that happens um often one loses you know I'm thinking about a a head-on collision between a Corvette and a Hami who's going to Biff it who's which car is going underneath which car and you can see what happens the low riding often oceanic plate the one that's more dense the low floater will Biff it below the high floater the h hve uh and gets what we call subducted right there so converging plate boundaries you can imagine what happens if a whole continent presses against the other continent we're creating again phenomenal stresses in there that should do something and often throw up mountains and make mountain ranges right there on that Impact Zone so it's a converging or slamming together of plates a transform boundary is kind of like a bad parking job this is when two plates neither separate nor slam together but they kind of slide past each other why is a bad parking job yeah you didn't eyeball it right and you will scrape your side of a car right next to the side of a another part car taking your mirrors off and making big scratches and dents on on both edges where they meet um this is called a transform boundary we're basically sliding past each other so this is a three main boundaries each one of them creates different geographies and we can take a good look at this one so let's take a look at diver plate boundaries where do things pull apart and create new new crstal material uh think about it this way here's a typical ocean floor where these things often happened is we are pulling things apart so in the mantle you have this upwelling here right we're hitting the ceiling this is my crust and they are moving then in opposite directions and it creates these stresses and it cracks my oceanic plate and moves each half in a different direction now because we have heat coming up here we also creating a lot of magma in this area and this magma of course molten rock will go up and then seal the crack that we create however because there's upwelling there's also pushing up of the plate so my my plate my oceanic plate not only cracks open but it also lifts up and we create a mountain range right here because of this upwelling and uplifting with a canyon or a crack in the middle that is continually being healed or sealed off by new magma coming in and we are moving these two plates apart and of course what the the question that is often asked what's happening um are there volcanoes on the ocean floor is this m is this water boiling there and all of the dead fish is fish soup if you rode a boat right in the ocean across this one you know could you see all the dead fish coming up and already cooked in your fish no the ocean has an incredible thermal Mass so you can ride right over it there could be a violent volcanic eruption right below your boat and you wouldn't even notice um where new crust is created down there this is a lot of hot springs in know water ocean water seeps in comes out right where it's hot right there it it creates these funny funny systems called black smokers or white smokers these there smoke stacks on the ocean floor full of minerals with some really really hot hot springs right along on this ocean ridge so here's one problem unless you dive down with a deep sea submersible this is really really difficult to investigate now there are some places on Earth where luckily an ocean ridge like this breaches the sea level and you can see it on dry land and you can investigate there so when let me see this this mid this is a ridge you can see that one that's all underwater this is by the way one of the longest mountain ranges in the world those right there wrapping around Africa then into the Indian Ocean so continues as the longest mountain range in the world created by a divergent plate boundary like canon in the middle kind of elevated spots right along this area and there is an interesting Island right there called Iceland and in this place that divergent plate boundary is actually above sea level and you can walk it and you can check it out and figure it out so Iceland um if you never visited Iceland let me give you a warning Iceland has become the Nordic Switzerland what do I mean by this one the Swiss know how to strip you as a tourist of all your money things are incredibly expensive in Iceland especially For Tourists and it's an ongoing thing where they charge more and more and more so it is really really difficult to find some um what we would call uh affordable accommodations like a hotel forget about raichik uh the one of the the Town Center is where the airport is actually right out there right outside rbic um is stinking the expensive uh what most people on a budget do you can rent a Jeep that's okay rent car rental prices going up but it's still affordable and they have a lot of open space camping I wouldn't go in the winter do this but during the summer months you rent a Jeep and you go out in the boonies and a lot of camping allowed on on lots of lots of open land there and you can do this cheap uh don't be surprised when you go to the supermarket though they want to buy some food it is going to be pretty dang expensive uh nevertheless my Mid-Atlantic Ridge is coming out there and you can walk along and you see it basically um on dry line you don't have to dive down you can walk along there and check it out by the way these red little triangles these are all active volcanoes in in Iceland uh often these these cracks uh are not in one spot they make little SPS coming off you see one here one SP is more active like this is a main SP this a little side SP um yeah the stresses don't necessarily crack it nice and evenly um so I've been there I've walked around there um when that cracks open you can see these beautiful eruptions with Magma oozing out this is a kind of a picture from Iceland um so when the crack is active and makes what we call a fish eruption you can see this one like a lava curtain and lava oozes out and then it you know the pressure goes down and it seals it all off off again with a new lava layer and exactly this would go on on the sea Flor uh just away from from view now you can fly over it with an aircraft and and see that that crack actually being active um but uh that crack follows the whole island you can kind of follow this along um it is there every now and then it opens up and magma comes out closes up again so it's not a continual process not always magma coming out you some periods of quiet time and sort of walk around um I've drove my car out there to this What's called the bridge between two continents it's just outside of rikic it's about this area right there um about a 45 minute drive from from the airport the airport is actually right here it's not directly in ravic um and you can drive out there it's it's it's highly recommended and you see that crack here it is and so I'm standing on it my one foot here is on the Eurasian plate the other foot is in the North American Plate as I took this this picture right there um at this edge of the of the island um my bridge between two continents so uh so technically Iceland is in two continents yeah wow my geologically speaking of course they count themselves as a European um country they were part of Denmark and then I think I don't know when they declared independence so they're no longer part of the of of the uh denm Danish mon monarchy uh they now they their own their own little country and can do their their own little government but they they count themselves to the European I uh they have their own currencies I'm not sure if they're the in the European Union they're probably not because of fishing rights that is always a one of the these problem but yes uh theoretically Iceland know scientifically speaking is on two continents that's really cool yeah so but it is worth I mean it is a beautiful place to visit go during the summer um lots of hot springs uh you can cook your food don't even need to bring a cooker this is some people say oh if I go camping I need to bring a cooker no just get some cans from the supermarket and lots of places you either have a a boiling hot spring there you throw your can in for 15 minutes fishing out with a stick and it's nice and cooked at this time or you can actually uh dig a hole into the ground a lot of places in Iceland you just dig down maybe 2 feet one foot and then you Barry you take a potato wrap it in aluminum foil bury it down there leave it in for an hour take it out and it's totally cooked I mean it's gets really really hard just a few feet below your feet um very volcanic island but a place to investigate a divergent plate boundary it's not always possible that's another place that is not that easily visited I for few um years ago I wanted to take students there and then politics uh International politics kind kind of did not allow this it's called the Great African Rift Valley um let's see where it's located so if you look at um Eastern Africa a little bit here's my Red Sea right you can see that Saudi Arabia uh in this area um there is kind of something interesting going on here's the enlargement of the map the my Red Sea right here Gulf of Aiden uh my Indian Ocean and right there something is happening Africa is splitting apart it's creating a new Rift Valley this is how the Atlantic Ocean started um 150 million years ago same way dry land it started to split open you can see that's my split here's where the African continent is pulling apart the Red Sea part is already split that's already pulling apart so the Red Sea will getting wider and wider and wider eventually will be as wide as the Atlantic Ocean this is how basically the Atlantic Ocean started as well but right here Ethiopia being being up there um is where Africa's currently splitting apart that part is sinking down the other things getting elevated and volcanoes are de veloping Mount Kilimanjaro for example highest peak in Africa is forming right on that splitting of that continent it's also a divergent pleate boundary and here is sort of how this whole thing happens we starting this upwelling my crust in this case my continental crust starts to split now as my continental crust moves away it's it's dragging off in this crack of course magma seeps in from the mantle and creates my prototype of a oceanic crust down there with fresh magma while the other side is basically pulling apart if that eventually um drops down low enough as we pull these two dis spit continent apart water will start coming in I'm going to cover this whole thing with water and I create basically the Red Sea um something like the Red Sea Ocean the same will happen here eventually water will kind of seep in and this will become a new ocean all the way down to to here um so it will get wider and wider and then um if this continues for several several tens of millions of years you really create a colossal ocean uh basically that was the start of the Atlantic you know 150 180 million years ago when we did all of this and now we have a very wide ocean there um but we started something like that you can see here and yes when you walk around there this great African Rift of the East African Rift uh they call it now the Somali subplate that's what we created there we having this drop down Valley and volcanoes along these cracks of course starting to appear so this very active volcanism on this on this Rift Valley um aerial photograph can actually show you some of these drop- down areas um there's Low Land so rainwater kind of Puddles we're making little little Salt Lakes there that pop up but eventually this whole thing will drop low enough it will be below sea level and then sea water can can migrate in and of course volcanoes will flank where these cracks are and this is Mount Kilimanjaro are really the the highest peak in Africa not quite um 20,000 ft yet little shy couple couple hundred feet shy of uh of 20,000 highest peak but it is a volcano an active volcano there in in in Africa and it's it's on the flank right on the edge of this of this Rift Valley as magma kind of seeps out and generates this volcano all right so that was my Divergence things pulling apart usually below sea level what about conversion plate boundaries well conversion plate boundaries a little bit more involved because you can have several post possibilities so we're going to generate a little Matrix here first of all we have two crusts right we have a continental crust and the oceanic crest and let's do the same on uh on the column here Nal crust and oceanic crust and now we see how we can mix the to how we can slam them together so you can see what happens we can slam together for example a continental crust with a continental crust right there we call it a continental to continental crust collision right we can also slam together a continental crust with an oceanic crust and it doesn't really matter which one we name first is the Continental to Oceanic or Oceanic to Continental it doesn't matter um it is the same outcome so a continental crust slams into an oceanic crust right here here's my continental crust here's my oceanic crust populates that field or here's my continental crust here's my oceanic crust populates this field so we can have a continental to oceanic crust collision and we also have in the last little field here in o to Oceanic Crest Collision now all these three actually this is the same one right here but all these three one two three uh create different Scapes different Landscapes of different outcomes let's start with a continental to oceanic crust collision what does it look like well I have a little lame animation here you have if you have a oceanic crust its density is 3.0 G per cubic cm the continental crust only 2.65 or 2.7 G per cubic cm what that means is since the oceanic crust is heavier it's going to be dragged or pushed underneath the continental crust we have something here we call plate subduction one plate gets literally ly swallowed up below the continental crust and nothing is more evident than this little picture than in South America where we have the Andes Mountain being bunched up right there as my nasar plate is dragged below the continental crust of course phenomenal pressures ensue we get a lot of buckling hence the mountains are being rised up raised up the continental crust is moving still Westward while the NASCAR plate is moving Eastward so we're creating phenomenal pressures right there where the oceanic crust bends down we actually create a canyon right there called a trench from the bending down of that plate and what happens to that plate that sucked under the continental crust well it gets recycled the Earth even rocks are great recyclers it remelts and then these molten pockets of Crystal slab are like bubbles in a lava lamp that will move up burn their way through the crust and create magma Chambers and feed volcanoes hence subduction plate subduction creates fuel for volcanoes and therefore most of the earth volcanoes if you ever want to see one are at subduction zones actually there's no subduction zone on this planet that doesn't have an active volcano so where you have played subduction through the remelting we create the fuel for all these volcanoes hence a continental to Oceanic Collision will create volcanoes we call that process plate subduction and it is one of the major creators of volcanoes of course there's some other creators of volcanos as well you know um there's some Oddities like Hawaiian Yellowstone they don't really fit there's no plated subducting there we'll talk about those later hold on we'll get there all the favorite favorite spots right so in South America if you take a slide through here remember where the plate bends down we creating actually a canyon called a trench then we get the buckling it throws up mountains and on top of that buckling we create magma Chambers and then inundate this mountain range with volcanoes this is why the Andes mountain range in South America is the second highest mountain range in in the world Himalayas formed a little different top down they are the winners as highest mountain range but Andes are seconded up um and they also have a lot of active volcanoes by the way this is something that the Himalayas are missing they don't have hardly any any active volcanoes at all but in South America on their West Coast hundreds of active volan sometimes to the shagrin of the population that have to live in the shadow of these volcanoes that erupt once in a while and cause some pretty pretty nasty damage and of course if you have two plates pressing against each other these little black dots what are those these are earthquake centers um a lot of cracking of rocks and fracturing so what does the andies mountains look like they are a form formable obstacle um high mountain ranges uh they're pushing into the 20,000 so a little higher than the Rockies you know I need to add another 6,000 ft on top of the Rockies to be there um and it's really difficult to build roads through here actually there are not too many roads across the the Andes Mountains you're going what so if you want to drive from Brazil over to Chile yeah you need to find a road there I don't know there five or six passes only through the whole length of the continent where you can drive most of them are dirt roads I think they have only one road that's actually paved over the top and it goes through a to a peak of like 18,000 ft something insanely High um to go over there so these are fairly fairly high mountains um and here's some of the dirt roads that go up there um of course animals look a little different than Earth but this is the top of the mountains right there um and you have to drive for a while over these mountain passes to make it through and of course these high mountain peaks can be explained with convergent plate boundaries oh yeah and that brings me to a little story that I would like to tell you and kind of conclude our first part of this lecture about PL tectonics driving up these mountain passes 18,000 ft is not easy it causes um engines to stall because of the lack of oxygen that's kind of amazing and it also causes people to react funny because of the lack of oxygen um you know if you fly in an airplane an aircraft needs to be pressurized because if you go over a certain altitude you would basically conk out because of the lack of all right so what about an oceanic to Oceanic crestal Collision right so what does that look like um so you have two oceanic crusts they both ride kind of low and they Collide now one of them will Biff it and in here's a general rule of thumb you can note somewhere which one of those two because have the same density right roughly 3.0 gr per cubic centimeter so how come one goes down and the other one stays up well the older an oceanic crust gets the denser it gets so an older um let's kind of exaggerate a little bit the older um oceanic crust may approach 3.1 G per cubic cm density the younger one may be closer to 2.9 and so the older one is the US usually the one that loses it and is being subducted because it's a tad heav just a smidgen makes it down there it creates this fantastic trench again as you can see and of it buckles down here there's some buckling but not much but we still starting the remelting process we're creating a lot of volcanoes and these volcanoes eventually start on the sea floor and then breach sea level and create a whole bunch of islands that are kind of like pearls on the string in a somewhat semicircle um Half Moon type shape we call these Island arcs and Island arcs are common on these Oceanic to Oceanic crustal Collision areas sometimes these volcanoes get rather big and these Island arcs will kind of fuse together and make a make a large gigantic Island dotted with volcanoes sometimes they really individual little Islands a lot of them we'll show you some where this happens right this is probably one of the most famous places of an island Ark um and I will tell you where it is this island Ark a picture I showed you it's Japan Japan is full of volcanoes right there this is my oceanic plate that's another oceanic plate we generating a trench here this Pacific Plate is older so it makes it below the Asian plate over there and we can then bubble up a lot of volcanoes and these volcanoes have grown so big over time that they generated a an an an arc that is kind of fused together of tiny Islands if you go Southward you see the individual Islands again if you go further south there's another famous Arc the Philippine Arc Philippine is also volcanic and the same story but Japan is probably the best example and you can see that where we have an oceanic plate being subducted below another oceanic plate we create Island arcs and here is most Island arcs in the world are in the Pacific Ocean so Japan Arc up there you see see the dotted Islands here another island arc here the kuril arc we have the ruuk cuuu arc that is not fused together this is more individual Islands here like pearls on the string the Philippine Arc of course um there they have been fusing together there's another Arc here where we have the the Indian oceanic plate basically being subed right here creates this island arc some of those Island have been fused together in a a Long Island you can see that one other still you know dotted like pearls on the string this is of course the Indonesian Arc um one of the most dangerous volcanoes we find in the Indonesian Arc mobot volcanoes that's a New Zealand Arc New Zealand Arc the same thing um we have some um volcanoes they are all volcanic if you want to see the volcanoes go to New Zealand one of our students actually got accepted in the PHD program she's studying in New Zealand right now um volcanology uh full of volcanoes here in the United States there's a kind of an interesting Arc lots of little Islands they're all volcanic all the way up almost into Russia you can see the aluan Arc in Alaska um if you ever FL to Anchorage right there right across as part of that Big Arc system is Mount read out um a very active volcano just outside of Anchorage um so lots of Island arcs do we have Island arcs in other places in the world as well yes but not as many there are some that are around the Indian Ocean hasm Pacific Ocean hasm we have one in the Atlantic Ocean only one the West Indies Arc right there you can see that half moon shape again and of of course there are some other interesting places you know Florida is up there oh our Bahamas the West Indies out there okay this is all part of that famous Arc with a subduction going on lots of active volcanoes oceanic plates are slamming together to create that that Arc so now Oceanic oceanic plate collisions of course with subduction we creating now the deepest part of the Earth um at these subduction zones we're creating magnificent large trenches you can see them here and there very interesting U what they call a b symmetry map where we show ocean depth and they are right along these Island arcs there some very very deep spots there's New Zealand down there and see that right along the coastline here's my uh uh West Indies Arc you can also see this uh subduction zone right here so and these are deep spaces they have to do with every time a oceanic crust is involved in any type of a collision we're going to generate these kind of deep spaces in the ocean um so we call them trenches ocean trenches they are not in the middle of the ocean believe it or not most of these trenches are right outside of Island arcs or next to continents and there are some of the deepest parts in the ocean um so the one for the West Indies Arc is called the Puerto Rico trench right here we have the alusan trench we have the Japan trench uh the deepest part is the Mariana Trench here with a Challenger Deep there the deepest spot so far mapped on Earth that's uh here it's interesting that is um a place where the volcanoes have not breached the surface sea level surface yet so they're still underwater volcanoes all along here in that in that Arc shape so there's no Islands yet they will eventually show up and give it a few more million years and then we'll breach the surface right there okay so let's kind of how deep are they and what's the comparisons so give you one that some of you may have visited um the Grand Canyon in the United States if you ever stood there on the edge and looked over it has a depth of about 1.6 km about a mile deep or so from the rim we're standing on give or take a few and then the average width you know some places it's narrow wider it's about 30 kmers wide looking from the south rim to the north rim and so forth so this is your comparison as I go through it and show you a few of these width and depth of some of these trenches so there's one the Java trench here depths 7.7 kilm compare this one to the Grand Canyon it's 1.6 you go whoa width is wider it's 80 kilomet but still it's quite a bit deeper um here's another one the one at the coastline there of South America the Peru chili trench depth 8 kilm even deeper than that one and the width is 100 kilomet so little wider than the Grand Canyon but also quite a bit deeper now I'll show you another one here here is the the the Ked Tonga trench depth of 10 km so we're going to count down here know where the deepest part of the ocean uh 10 kilm a width of 40 kilomet so that close to the Grand Canyon but what do we talking about five times as deep whoa that these are really really deep parts of the ocean um here's the Japan uh cill trench up there 10.5 uh um kilometers steep 120 and I think the winner is the Mariana Trench top one 70 kilm wide 11 kilomet deep that is incredibly deep it's the deepest spot on earth right there the Challenger Deep that clocks in in that one I'll give you some idea Mount Everest measured from sea level is 8,848 M high or 8.8 kilomet high so you could syn Mount Everest if we measured it from sea level all the way up you could sink it into the Mariana Trench and it would disappear below the ocean floor that's how deep it is so the deepest spot on earth is deeper than the highest spot on earth is um excuse me yeah mount ever is about like five five and a half miles high I just did the math okay five and a half miles good fantastic to know um but no matter what unit we express it as it will still disappear in the Mariana Trench and you can throw it in actually it would disappear in the Mariana Trench it would stick out in a Peru chili trench it would stick out a little bit but here this one um the kedc Tonga trench would go down and even in the Japan Tren it would completely disappear so this subduction G erated trenches are incredibly deep just wanted to bring this to your attention um yeah all created by PL tectonics right so if we cut a profile to the sea floor remember wager said one day we will see what the oceans look like and then it will surprise us all and here's sort of a a cut line right from the from the Philippines right across the Philippine trench and then into the Pacific Ocean and down there little hard to see the blue stuff here is the water that is sort of the profile so right there you can see we're going you from from Land all the way down to the depths of the ocean and there's some some sea mounts we cut across here the little sea mounts but you can see we're going way down that's a trench very deep and something along here Fair fairly flat then we have a look like a divergent plate boundary we're going back up again and then something odd happens two mountain ranges next to each other there's my subduction in the Mariana Trench and you can see and there is my deep spot and we have some sea mounts again fairly flat another sea mount fairly flat a few more sea mounts fairly flat and then eventually in South America we would look like this again coming out the the other end um so the seaf Flor is not a big Basin uh looks totally weird different than what we ever imagined um little bit of CGI if you would drain the ocean and then fly over it this is somewhat what this area would look like with a deepest spot the Mariana Trench like a ginormous Canyon right there presenting its view all right so that brings us to the last possible convergent plate boundary Collision what happens if we are slamming a continental crust into another continental crust well they are both high floaters and they're both very very thick so will one of them subduct not really really it's one of the ugliest head-on collisions ever so by Cheap animation we just going to buckle and push this whole thing up into the sky something like that right so has this ever happened anywhere on Earth and is it going on right now absolutely the highest mountain range on Earth is created exactly like this where two continental crusts eventually come together and this is of course our famous famous Himalayas highest mountain range on Earth basically two continental plates slamming into each other and pushing this mountain range ever so higher uh how this is ever happen Well India is slamming into the Eurasian plate creating the uh the plateau of Tibet behind there there's a very very high Highlands and then this massive mountain range now what you need to realize there is a little bit of a subduction going on why because as India was moving across the Indian Ocean toward the Eurasian plate it pushed ahead a sliver off an oceanic crust that needed to get subducted first and then eventually we came to the edge of the Indian Indian land mass and then it slammed with full force into the eurasion plate and created these this mountain range um so we have the highest mountain on Earth right there that's the reason why it is all explained by play tectonics Mount Everest is part of this fantastic mountain range very much Highlands here as India you can see it is kind of slamming into that area and creating an ginormously high mountain range um but because there is very little subduction because that was just the sliver of oceanic plate that got subducted and then stopped the Himalayas are incredibly void of volcanoes why because you need fuel for volcanoes no fuel no volcano where do you get the magma from we usually generate magma by having it a subduction somewhere that can then remelt and create the fu of volcanoes here very little fuel I mean they have a few volcanoes and I there might be one or two actives but this is it we compare to the andies I mean hundreds of volcanoes active right now himas me a handful if you get that many it's all left over from that little bit of oceanic plate that went down before India kind of slammed into Eurasian plate and of course this is sort of the the movement it was actually very very rapid movement from the India landman I'm going to show you a video here in a second um we're slamming into this one and we're generating here uh the enormous Himalayas of course India is still pushing with all its Force into the uran plate and it's riddled with earthquakes because of that incredible pressure that it creates right there and the highest mountains on Earth are right there um incredibly high mountains 29,000 ft something insane um not easy to climb one problem is with the tourism up there um I could tell you a lot of stories of what's going on um people spending $100,000 to climb up Mount Everest and um a lot of tourist trash of these very affluent tourists bringing oxygen oxygen canisters up and then they have some really um environmental impact with this tourism for people who want to just stand for a few minutes on the highest peak on Earth um but it is an interesting landscape it creates this the the roof of the world as the locals call it okay here it is Mount Everest sticking above a village in Tibet okay so one thing is what still unclear is how does a continent race with such a speed and with such high velocity well High Velocity you not not 100 per miles per hour but maybe twice as fast as your fingernails grow with so double the speed how did it make across the ocean and slam into um into the himas and so I have a video I hope this works I have a video for you um just came out from the University of Texas um that might be interesting to answer that that question