Geology/Oceanography 2 (Plate Tectonics)

Hey guys, welcome back! Today we're going to be talking about Plate Tectonics. Plate Tectonics is one of the most
important concepts in all of geology to understand. If you don't understand Plate Tectonics, then a lot of the rest of the course is going to be a little difficult to grasp. So make sure that you pay close
attention, and if you have any questions please contact me either on the
discussion board or by email. Let's just jump right in then. Plate tectonics was first
proposed by a German scientist named Alfred Wegener in 1912. He didn't call it Plate Tectonics.

He actually didn't know that there were plates, but he did recognize
this relationship amongst the continents… and… he believed the continents are moving around. We'll talk about he believed that here in a moment. And he called it "continental drift." Today, plate tectonics is the unifying
fundamental theory of geology. So, just to introduce our hero here, this is Alfred Wegener. He was a polar explorer, meteorologist,
geophysicist, just an all-around turn-of-the-century interesting guy. You know those… at that time…it was kinda the age of
exploration to the poles in and really, really interesting life. But
he proposed very controversial idea. And this is basically what he was proposing. I have an imagery over here… showing continental drift over time. This is
the number of million years ago. If you follow this arrow…this is time to present. And once it gets to zero, of course this will repeat. You can see that this is supposed to be an animation of, literally, the continents floating around
the surface of our blue planet Earth. You can see pretty rapidly why people might consider this to be a somewhat controversial approach to looking at the earth and describing the
processes that happen on it.

Because who would ever think that continents could move. Well, Wegener was the first one to
publicly say as much. So what we're going to go
ahead and do then is begin by laying out the evidence for
continental drift, as Wegener saw it. And we need to
understand a couple of important vocabulary words going forward. First off, when Wegener said that the entire
world had come together, he proposed that it was a single large
continent at one point. He called it Pangea.

Here it is right, Pangea… and that that continent existed about 200
million years ago. He also believed that there was
something called the Panthalassic ocean. The Panthalassic ocean is
basically one single, large, world-connected ocean that went all the way around this one, single, large
super-continent. And the reason why he believed this was
because he noted, right away, the puzzle-like fit modern of
continents…specifically the most obvious ones… most people see this when they're kids…
South America and Africa look like they want to fit right in together. But it also turns out that
North America…this edge over here and this zone over here as we go through…looks like a pretty good match as well for other reasons.

And when you do put it all together it actually looks like a good match. And
so, he went with this and he thought this was
the explanation for what happens on the Earth. The face of the Earth changing constantly. Of course this is a very controversial thing.
Another thing I wanted to bring up, just since we have it open, is this thing called
the Tethys Sea. The Tethys Sea is part of the Panthalassic
ocean, but it's right here on the edge between
Africa and Eurasia. And the Tethys Sea, at least the rocks, here that are underneath the Tethys Sea, are now part of… or the area that we now call…
Mediterranean ocean or the Mediterranean Sea. So it's geopolitically a very important
thing to understand. So in addition to the puzzle-like fitting that Wegener saw, new data had come out the 1960's that corroborated what it was that he had
actually seen. And that was the fact that a lot of
people noticed that the outline to the continents didn't match exactly with each other.

For example here's South America and here's Africa. However Sir Edward Bullard used a computer model combined with what we now know to be the edge of the continental margin… we're going to be talking about
continental margins a lot as we go forward in the series of
lectures…. but the edge of the continents actually are little bit underneath water. And that's
what these black lines here, along the coast about Africa, indicate…as
well as off the coast of South America and North America as well. And what that implied was that the continents were actually bigger than what they could see at the surface.

That maybe there was more continental material that was available. And sure
enough, once you match all that stuff up it turns out that Africa and South America…if you match up that edges
are the continents including the submerged part of it… you have a really nice fit. And this is also
true up here in Europe. Remember I said there were features? Look at this…here's Greenland which is part of North America… and of course here's the Scandinavian
peninsula… and it says just nice like a girl
breakthrough here and this was probably the using computer
models interesting stuff it's an interesting
hypothesis solved the puzzle pieces seat that is
there anything else well yes it turns out there's also a
mountain ranges that seem to match up so you and we look at modern North America here you have the
appalachian mountains here in Eastern United States into southern
canada in the British Isles we find the the
British Isles being Ireland right here Scotland up here in
the North I'm ironically it actually doesn't go
through Britain but you get the idea in the Caledonian mountains which also
extend through the Scandinavian countries appeared nor it turns out that the line up quite
nicely when you put them back into the Sun nice puzzle piece reconstructions and
that would be this mountain chain right here we'll talk about winds might form your
but anyways so not only do the mountains
lineup really nice bot they have some other features that
are poor they're similar rock types the rocks are the same age and the
structures on different continents corley crossed we're going to be talking about mountain
structures a little bit as we go through the course we're gonna find out some of them have
interesting root structures or this form in interesting ways and
that the structures to be found all the way through from the appellation
into the columns in addition to the mountain ranges turns
out there's additional evidence from glaciers so there's evidently ciation in now
tropical regions now this is a very interesting we can
make the argument that perhaps there was dude period time in the past on giant ICJ covered your in ice snow glaciers going everywhere but
it turns out that doesn't hold up that there are some places are now in
the tropics that were covered in snow over the place announced know that were then covered in
tropic so wasn't a case of the entire Earth ever being in case snow was not at that
time sold that is kinda interesting how do
you get trapped lyricists allAfrica covered with glacial
deposits these are dip sandstones and koppel's in things I can only get there
because glaciers moved there the other thing that we can do is
we can study glacial flow directions by the group by
the way that the established rules by it actually ripped rooms and scours the
rocks and it tells us the direction and saw
his era shows directional movement in monarch these glaciers he reconsiders in all
these cases they're going to or which implies that we should probably
originated under antarctica some point and sure enough
when you go ahead and you put together the pan to LASIK ocean you
put together a .png and giant land mass turns up all these glacial areas matchup they form a nice little balls i right
around the South Pole and they're all going away from the
Antarctic suck on her at this point so but the
antarctic continent as we see it today and indeed it doesn't
act support the idea that there was wants it
very large home super comet which had glaciers moving away from the southern pole which
is now America no se America me much but the
rest world's in plant and animal fossils indicate do different climate and today
there's lots of evidence that indicates that not only was tropical regions that we now have family and glaciers again the animal
distribution soon kind will soon move them tropics
now were in very different places back them
and it only makes sense if someone asks I'll means in addition we find some really
interesting distribution organisms for example you see this fossil here that dates back to the masses exists it
time as the dinosaurs it in the western half of the Atlantic
Ocean and it in this area that we know would
consider to be southern Brazil and then over here to
the west and southwest Africa and South Africa we find similar fossil man almost
identical fossils and notice the distribution is my
semi-circle here so nice semi-circle here there's
mountains on the side mountains on outside what's really
interesting is that we put South America and Africa together this
circle in that circle in there and this at a certain moment at
the Circle Line perfectly today so same fossils found in
comments that today are now widely separated and modern
organisms was similar ancestries ready so we actually see on common biological ancestries in areas
that are so far apart that they would never have form that way on their had to be together at the time separated
later on by Massey the Commons okay so let's talk about the actual
publication when this idea came you would think that this will be
revolutionary people with it you know taking it and think it's just
the greatest thing since sliced bread not all new theories combo that way so 1915 e big published origins continents and oceans and guess what you
do so by ramzi this is the copier we've fourth edition
you can so relate home you to see that he actually a
pretty good conception what he believed breakers pan Japan classical
notion here's Angie here you can see it
breaking up and of course he suggested the content
population basins your time forces least he one of the
interesting things have to build you sound like me with the
occupation yes please have to take a a good guess as to what you think is
causing it to happen he said tanks this of course was met with hostile
criticism and even open ridicule you he he was some believe that a lot really good
scientist in the end he wound up being right of
course about not necessarily his mold things moving
but his data his observations because it's all being
together one point he knew that they were together just to
explain why they had separated he was very effective at doing so and so
this actually was a big problem for his ideas for long in the reason is the proposed mechanism defies the
laws of physics you just use in time for so long as I
can be enough to move comment I heck you can take a rocket you
can stick it out in the street Nowotny the rock the when I say forcing me to
find actually when we're talking about tides ocean times it's really a gravitational
pull from mu that is pulling times up and down will be covering some mislabeling class but in terms love panel forces affecting comments and rocks is just not answer we
just don't see it happening the laws of physics show that the
gravitational attractions are just too weak to me so too weak to move row stand
approx so as a consequence the ideals live side
to the nineteen sixties the moment new evidence World War two essentially during world war 2 the
Kriegsmarine which is the German me begin doing hi resolution surveys of the ocean floor
soon after the United States began using so now
actually to do studies a the ocean floor I'm so in addition to
the sounding data the Kriegsmarine and the sea floor so
he's been done by the United States Navy to be a fine the submariners in the Kriegsmarine amazing data was collected we begin to
actually get out look at the seafloor learn what is
actually going on beneath seventy percent your service so also new technology in a
bit study Earth's magnetic field we're going to talk about that evidence
here term what it meant about BT the agency year so the problem howland the world
economies to move around wasn't solved least the ideal really
definitively salt to a minimum Harry asking he was a World War Two submarine
captain remember these guys at work in the ocean
they're looking at the seafloor closely because there not that they're
chips are you go down to the sea floor but makes them think about what's
beneath them I guess underneath the ocean hiding from the enemy he was also a
geologist it was a really good one in what he noted was that depth
recordings show seafloor features right we Captain James Cook made a
similar observation late 1700s but a lot of people didn't really take him as seriously as it
probably ought to Harry Hess said no there's a lot going
on down on the sea floor it's not as big flap were close as expensive land where there's just
water city was actually gonna be values is actually
going mountains is actually gonna be canyons all kinds of interesting stuff and he wound up giving us the idea of
seafloor spreading and his idea from seafloor spreading
came from a notion that he had a bus on the call mantle convection driving the Commons around not just the
contest elections within the c4 and the ideas really simple one you think about it is next year's Harry asset 1.0 in this
image over here is hopefully this all covered up you can
see this speak heat source and essential happens
is you have something up equal density you at the bottom part of
it he gets hot it's less than cinestars to
rise this is the reason why smoke rises as a
reason why bubbles rise up in your in your soup in
you wind when you're cooking soup you get these convictions I'll begin to
set up essentially become hoping they don't 30
in with the dump their key to get a little bit more deaths and they sit back down to the bottom and
then repeat the circle basically they turn into a nice here
engine and terry has came up with this idea he
said that this is happening down at the
bottom of the sea floor it's very possible that the sea floors
actually be ripped apart and it's spreading apart at
different places fascinated course little lip service
Obama comments talk about wise course goes forward below the seafloor be able to get a
really good you turns out he's completely right so the structure of the sea floor as we
now know it based upon some stuff that Captain Heska reported was that essentially there was
a convection cell existed in the mantles as a mental
strain to the rules hot material up to the top it in order to cool itself that you set up
a convection cell underneath this seafloor nielsen another
convictions on me seafloor justice on a little heat engine
diagram I was present essentially what this does is it brings
hot metal material up to the top and as it cools it slams it basically adult form hot molten rock that hot molten rock
will crystallize and form new c4 straight out to the
sides and essential convection cell phone way
up traction friction on the bottom 0 was
basically a plate crossed that exist on the surface of the
earth with separate away from some central point that he called his friends and the spreading centers would
basically be characterized by nice returns are in nice amid rift in the middle and then when it
spread out to the side form trenches right along where dive
back into the into the earth and the reason why would
I back when the rats because if you're stretching it here you can get the earth larger it has to
go somewhere so it would dive right back down do
something 'cause options is made a couple interesting
predictions first of its adjusted at the center of
the oceans were no longer the deepest part to serve always been believed that you
want to go to the deepest part of the ocean you went to the middle of the ocean this prediction is that known fact
probably near the centers or at some point in the middle of the oceans is
going to be spreading center and at the spreading center you actually
gonna get hot rock this is a little higher than the cold rock around it for density reasons and as a consequence you're actually
gonna have this nice hi mid-ocean ridge sitting up here in the
middle is gonna be bach Annika follow earthquakes and all kinds of cool
stuff but the deepest part of the ocean actually be strangely enough right near the
landmasses right where this oceanic crust would
dive down now he didn't really get into the
details why it would go underneath the large lawn
asses but that was the prediction so if you had a subduction zone you have
a transaction that would be the deepest part and in the middle would be actually is
not nice hai par turns out it's completely right additional evidence came out with the
fam magnetic stripes on the seafloor so women began in 1963 to publish an actual interpret the sea
force magnetic signatures we we had and absolutely amazing revelation about
the spreading search right as this confirmed what captain house have long been saying since the fifties
essentially you get a straight answer formed by
Magna you get basically zero show that you're
moving this part over here to the left start right and its ripping open the
surface of the earth right at this point here and ass ripped
it open Mac comes in fills in the gap and interesting things happens the earth
has a magnetic field and that magnetic field the some really
interesting things over geologic time right now the magnetic field points the
more but it won't always do so benchley will
slip point to the cell that point nordica middle point sup and these reversals as their
so-called occur maybe every hundred thousand years two hundred thousand years or several
million years turns out there's no regular reversal rate but it does happen and we can see it in the sea floor that
we have period of time where the direction of the magnetic field will
be locked into the rocks because the rocks have hired leopard and it will preserve that
magnetic stripe day where that magnetic direction K and essentially over time more spreading
would occur and this time does rock separate hear
this young girl and right here is now ripped off to the
side here ripped off the site here and more Mac
come in fill in the gap in the center but
perhaps and during the time that this phone is forming the magnetic fields switch the errors
are now reversed and then again the process repeats that
there's another magnetic reversal more man becomes insolvent but this time
it preserves the also feature so what happens is you get patter love about reversals that you can see on all sides a straight answer so this rockin this rockin same age this
rockin this rock in the same age and this one here is for me essentially
today in the late nineteen sixties there was a
deep interest in the agent the ocean floor love it was based upon how all these
magnetic stripes were really wanted to know when these things happen so they can
correlate rocks for example Pacific with some
already planted just using the magnetic signature they
can figure something out about that and so they went out and they started
drooling all over the world and what they noted was that in fact
they found mid-ocean ridges this one hears in the eastern Pacific
here's another in mid-ocean ridge do right in the center up the Atlantic Ocean other specialists
2 a.m.

Crash over here in the Indian Ocean and passes right over into this here home but women look at the aegis of the
rocks on both sides all the mid-ocean ridges they noted
something very interesting that just as the strikes would show that
there would be a isometric spread in the ages also show that there
will be is symmetric spreading knows he
predicted by the magnetic stripe hypothesis born in the 90 early 1960s 1963 but what really blew them away was
how prolific and how predictable it became so for example here you know that the
mid-ocean ridge in the East Pacific is called East
Pacific Rise actually sure now we see rocks that are between 0 and two million years old
basically just recently formed and as we moved always in this direction the a progressively older to the point
where the cover the whole all those rocks in the ocean about a hundred and
eighty million years old you go off in the other direction you'll
notice that there's a zone up this p orange color that matches those or p orange color you find on the
other side it's all that pattern tells us that the
hypothesis mid-ocean ridge or spreading centers is true will know so the symmetry here's without
a doubt right almost looks like a two-lane
highway 121 weigh 120 other way but it's clear that we see not only look
brown the same each year around the same age here we see it here
we see a here in addition to the magnetic stripe being addition to the seafloor ages there is
additional evidence though what we now call please
tectonics was coming along and that is looking aunt earthquakes
which is safe quick up the stairs where they actually happen and you'll notice that here is the
Pacific Ocean this whole thing here's Pacific Ocean Jalota sisters is owner red and these
are worthy earthquakes happened on this again is
that East Pacific Rise where the rocks are really on presumably
this year rocks are being created no to settle as we will be here into
Asian Japan that we see big zone red along through
here california's San Andreas Fault area right here and we
see this nice on the road this zone at the centers clearly works out what we now call the
Pacific Ocean or the Pacific Plate you look so there's
another plate right here beautifully be marked by all the earthquakes around it here's the
North American plate again all right here right up into the North Pole Asian or the Eurasian Plate same thing knocked
out by this whole range little complicated we're Himalaya
Mountains Africa fantastically interesting in courses the East African Rift this or
paragraph is actually strand Inc you could start seems I'm
even today alright so earthquakes is evidence that
there's actually edges to when this stuff happens and it
correlates very nicely with what we saw I'm gonna go back again
to what we saw on this map is while so we on rocks also earthquakes and they also seem to show
really good magnetic reversal data and so we define the global plea boundaries in other words the the notion
that the earth was made up brought Prost the earth is not just a
single Spears but a bunch of pleats all interlocking
with another and moving relative to one another and
that these boundaries arm Apple on local based upon these
earthquake data so this will be the Pacific Plate here this is the Australian play course extends here and simply to quit largest
North American all the way up here what is it so large
is this when you're the one who could play slow smaller boxes located right here the coast Northern California
organ and Vancouver Wash crimes are going
Cooper British Columbia another smaller be
school Shipley located down here but again South
American plate the African players huge now we've been able to get a ser really cool Dana these things first we noticed that these errol's indicate
the directions that the plates are moving so here we see some the South American
plate is moving to the west but the NASCAR played over here is
moving to the east the Pacific Plate is moving to the
northwest the North American plate is moving to
the northwest so this is an interesting relationship
that results in the san andreas fault right here in California and we can go on all day justina
just-completed comments fascinating stop another thing that is
kinda interesting are these numbers your receipt well you
receive sixty here we see a sex what these numbers
indicate is the spreading said is the spreading
rate so you'll see the numbers overhears it
turns out that these this is war the Pacific Plate running
into the Eurasian Plate Eurasian Plate is moving into the pacific plate so it's not creating any spreading
centers but there is a spreading center here
right nasty plays going to the east the Pacific plate to the northwest so we
have spreading here 16 and a half centimeters per year that
a lot of sleep at the same thing is happening down here
in the African Plate purses of American Plate at Moonee away from each other at three and a half
centimeters per year appear in the northern part the African
Plate North American plate two and a half sanders your absolutely
fascinating stuff so perhaps it's just that there's two
kinds across number there's continental crust to oceanic
crust so the continental crust made up less
tense minerals not you we have the stock things like
quartz these adult stars and basically predominately grant so here's a granite
here so were I'm filming from here why granites are non-existent must you go to
Home Depot your buyer ground tabletop right other than that your plan granite
anywhere else I'm what are some other the properties ran
well tends to flow well on the Earth's mantle it's very white it's very low density and as a consequence is home to the
Tallest Man on Earth unless it calls me on earth I actually
should save highest point number between interest tells me Americans actually monologue
Europe why not Harper more actions video right
now actually a thing about these rocks as
they can be quite holes on comic-con panel price to point B 3 billion years old you don't
find ocean basins I'll dole's last week by male singer 180
million years old because about side retarded in the
convection cells so an example would be most to the north
american play right down really good example it also another good example the most Asia most
other wall Australia you get the idea iraq is basically beers sticking out war oceanic crust made a condenser iron and
calcium very minerals in basically basalt is the kind of way
that is made up of these times minerals and because it's denser it sits
lower on the Earth's surface usually covered by oceans tends to see back into the earth when it
grows older cold when things get cold to get dance right think about when you heat something up
likened iron or peaceable it actually expand when it gets hot but it when it cools
off it contracts which means actually denser when it's
cold and when it is so when it gets all that oceanic crust all it actually cools off over time and
it's more likely to see and as a consequence the ocean across
recitals at saw completely every few hundred million
years right right now boulders also impressed
again third said it its importance about 180
years old it's also home to the deepest trenches
on earth well menstruation in Western in the western Pacific bordering on to
abuse is are not far from bookings should see is loaded cases occur anybody does not seem small this is
black way over here explain so throughout this
presentation hope you're realizing that mostly accident occurs on planet
earth doesn't necessarily have to be in the middle of the sea large expanse place even though there's
some interesting things happen usually the most interesting things
happened to play boundaries so you know you're talking about the
specific price that's where the hoes the seafloor spreading free brand new c4 new new ball candles earthquakes all
along that line on the other side of the pacific
applicable dives down underneath Russia in eastern China in Japan home against future earthquakes large
volcanoes of a lot of amazing things are happening over there so I think it's important we spent
little time talking about type angers and there's reprints all types there's divergent police and essentially divergent plate
boundaries for you to place and they're moving away from each other
basically because the mantles coming operator need here splitting to plates par now remember what does part her whatever
comes up must come down and that leads to the convergence place
right work age limit bumped into each other here's one moving to the right this from
lot and the one on the that's moving to the left is actually
gonna sink down pharmacy options here's your scratch for me the ocean on as this play went back into
the now into the mantle the third time is transform boundary where we see two
plates one moving this case towards you you're
the one away from you if you think about these
two blocks is being three-dimensional some way from you custom toward you in
between it is a sliding area where they will past one
another this is exactly what the San Andreas
Fault is essentially dude Pacific plate is merely one direction
the North American plate the opposite direction fault so we're talking about the Sandy
tokars assalam easy features very poor first we'll talk
about the divergent years is dubbed the divergent boundaries
are really what gives most information about
plate tectonics at least the early so as basically this four stages
masterpiece your images here represent and sensual you get I'm of working up the crust due to the fact that you
have you he'll love hot mental moving up basically trying to you back to a back
seat and it puts tension forces on the crust in search
ripped across the open c1 getting or ping volcanism all kinds of
interesting things and over time you develop a call ripped
out so right here we see crust is being ripped
open from side to side you get these fall
blocks crackdowns trio debates are Iceland has seen the sexes features and if it's
actually been in the Westin st.

To see someone things as well home ASI the Rift Valley is essentially where the mad reaches to the surface and
searched for new processor tools in this gap those formed used to
you portions across ripping into overtime you get a lear see that formal because
the water will eventually intrude into this region home and and covered up but you're still
going to see them ripping apart the crossed at this point but in the middle your for me oceanic
material salt is coming up selling it in
informing brand new c4 in overtime when you get enough distance you get a continental crust on one side
of the ocean another Connell Crossland you know so the ocean them the sea floor living stems from a
mid-ocean ridge the center with a central wrist soul on both sides missus essentially a
cross-section over North America to Africa basically from Georgia to
Morocco absolutely fantastic but this is also
typical what you see certificate you one looking
their our students some other cool features that we should
keep in mind is that the fam we've already talked
about it rip dollars in things like this but shall focus earthquakes right
earthquakes tend to form very shallowly where there's not a whole
lot of material underneath there that's gonna break has got basically magma and eat
that saw gooey mantle is compacted right you're not going to get a lot of
hers pixel earthquakes right at the very sir matchup traditionally have made a
scientist and we'll actually observed that in fact is the case that the earthquakes to
occur very shallowly in the earth's crust a
mid-ocean ridges so here's a map amid Atlantic rich which cool right through the centre the
Atlantic Ocean and this is the longest mountain chain
world she's completely under water in addition to the divergent boundaries
richer extremely important there the Comber Jeep missed three types
there's the oceanic to continental which which is where we see the oceanic
crust subducting me the continental crust we have oceanic to oceanic where we have
again one oceanic plate but this case it got
to meet another oceanic plate and in the course third
type is too kind a comment Press running into him no question that
happens he should ask little crosses much less
tense the oceanic fresh lows of disappearance
them the oceanic crust always ok and here
they will probably take terms as happens the New Hebrides so specific continental cut no not necessarily going
to get a winner and a loser you're going to wind up getting massive
mountain ranges miss exactly 94 min away because India is coming from one
direction Asia from the other direction and they're pushing up China which so there are some really interesting
convergent boundary features we need to keep in mind first
off we need to keep in mind that convergence be safe please moving towards one right and this in this case we see oceanic crust
over here so anything that is on the ocean crest
here is moving towards this section comment on crest over here that overtime you should rest is destroyed white because it's
literally shoved underneath the continental crust and it begins to
melt there's basically the formation ocean
trench occurs here that basically shows the
point where the oceanic crust polled under or pushed under any yes underneath the comment crossed and the
form issue a walk in a car we turns out when you take a little bit
a water committee rocket bring it to hide temperatures as use adopted basically
forms the neser material to make magma magmas
molten rock very deep levels and reforms what to
call unit are sure large volcanic mountain
chains on comments so think I love Andes Mountains South
America Indian tired ballgames in addition that you get deep focus
earthquakes because here you have continental crust you have lotion across
the coming in together you can get earthquakes all along the
subducting slab the subducting oceanic crossed as it comes down and it turns
out that this course as you move inland the earthquakes good deeper and deeper
in deeper us great forces are involved it takes a
lot of force to make a subducting oceanic crust happen it takes a lot of course some people believe that mineral
structural changes are so silly as what do you mean by this is that as
you push rocks down to very high pressures under very
high temperatures minerals actually begin to change in the
fall think about going to lose ground ewbal thought about dying and being a downer
carbon graphite the nato hard what's the difference between the
two basically what happens is that graphite put under very high pressure and the
right temperature situation was formed basically what they're saying
is here is that you might get earthquakes
columnist by these minerals changing right as the
word just to change the minerals within it something is a bigger so much smaller
some have different strengths I'm is considerably strong group dancer
Graham for example any news the last I put convergent boundary want
to talk about is the continental continental
convergence right no subduction right in this case are no winners to
content run into each other that just run into each other something
to keep bringing chips into each other for a while you 128 Hall extremely tall mountains
upward and the himalayas India from the India
Asian was this is actually a picture highest
point on planet Earth that is everest there and what's really
interesting is when you go to the top of Mount Everest is actually marine fossil top because a lot about materials to
showed up into them due to the comic convergence in addition to the conversion into the
divergent course we can't forget about the transform boundary futures sold the most classic
transform boundary we studying as geologists of course is
the san andreas fault this is a photograph a marriage snorkel
San Francisco please call Point Reyes National Park this is breaks estuary anybody's ever
been there biggest a beautiful place it was a truck on the
Pacific in on one side of the pacific plate and the North American plate in this
case was moving down here to the left the other one is
mainly appear to the right and they're not subducting one beneath
the other they're kinda getting along they just
have to pass each other nicely in this is essentially what's happening that doesn't mean they don't get hung up
from time to time informed very large earthquakes los angeles-based work in San Francisco
area but for the most part it's a lot easier plate situation and for example what
happens Japan forms large legacy consulates image so company will transform fault cuts across the continent center is
false to for example transform faults occur
between mid-ocean ridge segments as well home you can look that up in your
materials that I have provided for the class home and it will describe the difference
between six and interest hope transform Baltimore would see at
the mid-ocean ridges still very very cool stuff and what does it look like will
transform all ranchers well looks like this uses a little earthquake
occurs that has occurred you can see this farmer wrecked in the
middle was feel kinda fault course he knows better he plowed field let me put his crops in
there and you could see that everything on the site has moved to the
left everything on the site is moving away absolutely cool stuff it does turn out that there's a lot of
things that do happen in the center the plates as well the just not as
concentrated for example the Big Island of Hawaii
this work away is currently its spewing out law every single day it's been doing it since the night since
the early 1980s on where the middle who plays miss you
know subduction happening nearby is no
formation mid-ocean routes nearby why do we have
this year in the reason is because we believe
something called mantle plumes in hot spots and what are the seats interplay
features create organic islands with a plate and even
and James course normal wise batton I'm change was not the only one that does systems
example home in the beauty the city's the record
AG plate motions and these H plea motions could be recorded in
something called military X haha track to explain what in the attack
is 14 so here's the Hawaiian island and
Percy cement unit here we can see mantle plume coming up
this is basically a plume a pop magma that her haha wrong that forms magnet down here at the
bottom the oceanic with the sphere which then transmits
material up to the circus informs a volcanic chain right now this
is the big arm great here underneath that is as large
metal pole but the plate is constantly moving in
this direction is demonstrated by the Sarah you expect to
see that if the sports t steady not moving but the crossed above it was me Miller
appealed it moved across did that there would be a wind turbines moving away in fact that's exactly what
we see here we see why your school why over
here inquires 38.8 5.6 million years old but there are no
locks younger than 3.8 man older than five points so so that
tells you this is where the plate was 3.8 25.6 million
years ago that it was in fact back here innocence
moved in this direction same thing midway these all form from
the same hospital since has been dragged away and
eventually the Big Island why would be dragged up here as well is
all drago further and newlines down behind them currently right now to leave you see now
seems be top candidate to replace big around as the new
youngest I'm chain so what does this look like from space
here's an image of the earth using Google Earth and down here courses the Big Island here's the horn chain but underneath here where to look musings
really great satellite technology we actually have a
pretty good idea of what the large features about the ocean and we can see that
there's a syriza undersea seems basically all Islands all quien Islands anderson's
crumbled in falling back into the ocean overtime we do see that they come
straight out off to the west to the northwest in a
straight line this is that needed that step hotspot
track that as the the hotspot his state
station right here at this location the plea over it has been moving to the northwest
but knows that there's another set of cement sidewalk to the north and they have a different direction than
what you see and why the sudden turn right here this is
called Emperor seamount sorry here and it goes up here sadat's underneath Russia this is the contractor
rest the kamchatka Peninsula eastern Russian and what does this imply well pretty simply well it implies that this not that the Pacific Plate used to
go in this direction innocence change to moving in this
direction that happens this is also this also
indicates that plate tectonics is constantly moving the directions on
the plates overtone this indicates a change in the
directional Pacific Plate the time with the formation BC its is so what makes home hotspot locations
and mental problems so interesting is that explains some really into the
really fascinating features that occur with in plea congress they're
not always on the to the plea so when we look here at simply you receive why there's a there's
this hot spot right there but there are other
ones to use one small a couple other down here and saw Pacific we see them all over and occasionally
even in the continent's especially here in
Africa Sequim need one appeared Germany absolutely fascinating so we actually
see the mental through the proper through the process
convection is trying to basically cool itself down and is due and in doing
so strikingly large heat engine that is putting mantle
plumes Upton services clues huge amount to pressure from
across the plate cupping to destroy itself in some places not for me to question other places
conjure as a consequence been floating around almost like bottles I'll talk about
because they can't sadat moving around at the Wimbledon mantle me
absolutely fantastic is also explained the relationship
between bomb kills and coral reefs overtime there are three kinds reefs that we
define home occurring all around agent volcanic I'm its sensing reaches the first time barrier reefs and finally at Hall's at all usually come with a large looking in the middle of it K this is sea level
across the whole thing what's the difference between wall of wrenching reforms when the
volcano first hopes its head out on the water the reach was formed the corals
basically will writing roundly add to the island overtime that crossed all all away from the hot
spot that formed that Donald leaving the reef right where it was but
the overtime the Joaquin will begin to erode fall
back into the ocean and leaving nothing but the reach for
the at all at the spot with just a shallow lagoon
in the middle what used to be the center affordable you know once once so space in future predictions so assuming the same direction and radio
plate motions is now contact but the impersonal is changing
direction that occurred about fifty million years
ago Stanley so on all over such a row but will we
see well we should see that the Atlantic
Ocean well as large in the pacific will shrink you see from you the East African Rift
will form from the rebellions the Himalayan
mountains will get even taller North and South America will eventually
separated one from another in that part of california might
actually wind up in alaska so let's see if these predictions occur
all is no way to really know course because the mechanism drives
falls down we generally see those things all you
see responses Iran's so here's a prediction what the
world map fifty million years the future will look
like and you'll see exactly what they're predicting South
America me to the west North America will need the
Northwest the Eurasian Plate will look to the
north and we'll see a smaller you players pushed you further into the Eurasian Plate otherwise it's not really a whole lot that's
expected to happen the next fifty million years 0 long if those East African simply
trying to break off enjoying basically the Red Sea here anyways hope you found this lecture
informative and useful and next week will be presenting to really interesting lectures dealing with
Adams minerals and beginning over discussions so hang in there and knows a lot of
information coming at you about some about a whole new subject but once we
get into it you sir see how it all fits together I think you're gonna
really enjoy this see you next time

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