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
amazon.com 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
