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we know that new plate material is being formed
, and these little spheric plates on the surface
of the earth are moving around
and that might raise the question in your brain,
what happens if we kind of reverse things?
we know the direction they're moving in
what does that tell us about what they came from?
so lets just do the thought experiment
right now south america and africa are moving away from each other
becouse of new plate material being created at the mid-atlantic
rift. lets rewind it. lets bring them back together. lets bring them back together
we know that india is jamming into the eurasian plate right now
causing the himalayas to get higher and higher
what if we rewind that?
lets bring india back down towards antartica
same thing with austarlia
we have new plate material being formed between australia and antartica
thats making the continents move apart
lets bring them back together
lets rewind the clock
even north america its not obvious from this diagram
but if you actually look at GPS data its pretty obvious
that north america right now is kinda moving in a counter clockwise rotation
so lets rewind it into a , lets move back
moving it in a clockwise rotation
instead of eurasia going further away from north america lets bring it back together
so what you can imagine is a reality
in which india and australia are jammed down together into south, sorry,
into antartica, south america and africa are jammed together, north america is jammed in there
essensially eurasia is jammed in there too
so it look like there all clumped together if you go back a few hundred million years
and based literally on just that thought experiment you can imagine at one point
the entire all of the contenants in the world merge in to one super continent
and that super continent is called pangea
pan- for entire whole
and gea- coming from gaia- for the world
and turns out that all of the evidence we see actually does make us believe
that there was a super continent
called- well we call it pangea now, and obviously there wasnt things on the planet calling it anything then-
well there were things back then but nothing that will actually go and label continents that we know of.
but all of the evidence tell us that pangea existed about 2 hundred to 3 hundred million years ago
roughly maybe 2 hundred, 50 million years -give or take- years ago
an i want to be clear this was not the first super continent
too largely agree is kind of the first, the most recent super continent that is easy for us to construct
becouse its the most recent one, but we believe there were other super continents before this one
that if you rewind even more that you'll have to break down pangea
and it will reform but were not going back in time
or that there were several super continents in the past that broke up reform, broke up reform
and the last time we had a super continent is pangea about 2 hundred and 50 million years ago
and know its broken up into our day, current day geography
now, i wouldnt go into all of the detail on why we believe that there was a pangea
about 2 hundred and 50 million years ago or this diagram tells us about 25 million years ago give or take
but ill go into some of the interesting evedienec on a very high level
you have some of alot of rock commonality between things that wouldve had to combine during pangea
probably the most interesting evidence is the fossil evidence
there a whole bunch of fossils and here are example of it from
species that were around from 2 hundred to 3 hundred million years ago
and there fossils are found in very specific places
this animal right here cynognathus
i dont know if im pronouncing that right cynognathus
this animal's fossils are only found in this area of south america
nice clean band here
and this part of africa
so not only does south america look like it fits very nicely kind of into africa
but also the fossil evidence make it look like there was nice clean band where this animal lived
and where we find the fossils
it really makes it seem like these were connected atleast when this animal lived
maybe on the order of 2 hundred and fifty million years ago
this species right over here
its fossils are found in this area
let me find a colour that has more contast
in this area right over here this plant its fossils
now this starts to connect alot of dots between alot of continents, in this entire area
across south america, africa, antartica, india and australia
so not only does it look like the continents fit together into a puzzle piece
no only do we get it into a configuration like this but if we essensially rewind it
the movement that we see now but the fossil of it also kind of confirm that it fits together
in this way
this animal right here we find fossils in this nice stripe that goes from africa through india
all the way to antartica
now, this only gives us evidence of kind of the more southern hemishere of pangea
but there is other evidence
we find kind of continuing mountains chains between north america and europe
we find a rock evidence where you know just the way we see the fossils lined up nicely
we see common rock that lines up nicely between south america and africa and other continents that were at once connected
so all of the evidence as far as we can tell now does make us think that there was at one time a pangea
and for all we know all the continents are gonna keep moving and maybe in a few hundred million years
we'll have another super continent! who knows?