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[Music]

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for those of you who don't know me I'm

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Jay crawl I also go by Alec that's how

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you'll find me on social media I use

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masculine gender pronouns he has in him

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and I study I'm a graduate student at

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the University of Colorado where I study

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one how gender and sexuality affect the

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academic outcomes for Gen chem students

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more topically I also study sulfur

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reactions and atmospheres in planetary

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atmospheres I'm not going to talk to you

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about either of those things this

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morning I'm going to talk to you about

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rocks cool so more specifically I'm

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going to talk to you a little bit about

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some of the rocks that you're going to

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hear about in this morning's session and

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why we care about them as

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astrobiologists to the geologists in the

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room please forgive me and correct me

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during the session after so the first

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rock that we're going to talk about is

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Venus it's often referred to as Earth's

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twin more accurately it might be

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described as our evil twin on a bad hair

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day but it's very similar to earth in

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size and mass and Composition but a

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couple of things make it very notably

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different especially at sulfuric acid

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clouds so from about 50 to 70 kilometers

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there's a global sulfuric acid cloud

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layer it also has an incredibly slow day

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so it takes about 243 Earth days for

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Venus to turn once on its axis and it

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also rotates in the opposite direction

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of all the other planets this is likely

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because of some massive cataclysmic

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collision or earlier in its history it

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also is incredibly hot at its surface

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about 500 degrees Celsius and if we take

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a look at its atmosphere that's a little

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bit easier to explain the surface

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pressure is 93 bar it's almost 100 times

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more pressure at its surface than on

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earth

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and that atmosphere is almost entirely

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carbon dioxide and so it has this

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incredibly potent greenhouse gas

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atmosphere there's some nitrogen as well

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as some other trace gases most notably

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so2 but because of that global cloud

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cover it has this incredibly high albedo

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which means that almost 90% of the light

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that is in coming from the Sun actually

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gets reflected away from Venus but the

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atmosphere is so thick that even that

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10% that gets in and absorbed by the

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planet leads to incredible heating of

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the surface there's also very little

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hydrogen and Venus's atmosphere and

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there's an incredibly high d2h ratio and

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so what that tells us is that actually

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Venus has probably lost a lot of the

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water from it which is interesting

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because early on its history we think

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Venus may have been a lot more like

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Earth and had oceans on its surface

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today its surface looks incredibly

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different though there is because of its

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similar size and density we assume that

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it's pretty similar to earth and that it

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has a core a mantle and a crust however

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we don't have a lot of actual direct

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evidence about the internal structure of

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the planet we don't see any evidence of

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plate tectonics which is pretty

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interesting and there's no magnetic

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field however most of the impact craters

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are almost in pristine condition the

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surface is very young only about 300 to

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600 million years old

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and there's been a lot of evidence of

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past volcanic activity and so what we

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think happens on Venus is that the crust

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is doesn't we don't have any of these

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plate tectonics right now but the mantle

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slowly heats up and at some point

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there's enough to actually enough energy

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to actually disrupt the crust and then

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we see massive turnover of the surface

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and resurfacing of the entire planet

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with so if we go a little bit farther

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out in our solar system we've got Titan

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it's the largest moon orbiting Saturn

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but perhaps most interesting is that

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it's the only moon with a

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atmosphere and the surface is composed

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mostly of water ice and rocky material

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but this dense atmosphere is possibly an

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analogue to early Earth's atmosphere

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which is what makes it really

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interesting to us as astrobiologists and

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so its atmosphere actually has a very

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similar structure to Earth it has this

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troposphere where we see all of its

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weather and then an upper stratosphere

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where there's a stolen haze which is

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mostly carbon containing organics with

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some nitrogen in them and then a miso

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sphere and thermosphere its atmosphere

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is almost 90 almost entirely nitrogen

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it's about 98% nitrogen we do see some

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methane

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it's 1.2 percent overall but as you go

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closer to the surface actually increases

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to about 5% of the atmosphere and that's

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because it's incredibly cold and so that

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methane actually begins to freeze out

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and you get precipitation of it on the

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planet in this lower troposphere and

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there's a little bit of hydrogen and

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then there's a lot of trace organics

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formed because of the photo chemistry

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that goes on with methane before Cassini

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cassini-huygens we actually did not know

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a whole lot about Titan surface

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thanks to that mission we actually do

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now know that there are hydrocarbon

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lakes and rivers and that the surface is

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actually pretty geologically young

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somewhere between a hundred and a

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billion 100 million and a billion years

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old but we can actually see these canals

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and rivers on the surface as well as a

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number of lakes at the northern pole of

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the moon as well and then also

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particularly interesting it has a rocky

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silicate core about 3,400 kilometers in

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diameter so it's a little bit bigger

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than Earth's moon but smaller than the

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earth but there's a lot of evidence that

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there is a subsurface ocean possibly a

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global ocean and what we think would

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allow for this is actually an ammonia

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water mixture so once you have enough

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ammonia in that water you can get this

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eutectic mixture that doesn't freeze out

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until much colder and so that also gives

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us the potential for a lot of

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interesting chemistry and importance for

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astrobiology the next rock that we're

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probably going to hear about is

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meteoroids and the IAU definition is

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incredibly specific it's a solid object

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moving in the interplanetary space of

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considerable size considerably smaller

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than an asteroid and considerably larger

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than an atom and so this actually gives

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us a pretty wide berth but most of these

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things are about 4.5 billion years old

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and perhaps most interestingly about 15

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thousand metric tons of these are

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delivered to earth every year and so

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these are a source of incoming material

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that can seed the planet with a lot of

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interesting material over you know the

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course of billions of years additionally

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most of them come from the asteroid belt

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about 99.8% of meteorites that we've

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found have come from there and so they

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can tell us a lot about the early solar

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system composition and some is well our

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cometary debris and so that's normally

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what we would refer to is like a meteor

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shower and then a very small number of

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them are ejected material from

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collisions with much larger body such as

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Mars in the moon and so these are some

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of the first hints that we got at what

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composition what the composition of Mars

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and the moon were after that we'll hear

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about some stromatolite some

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stromatolites are a little bit different

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than all the other rocks we'll be

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talking about one there here on earth

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which is exciting

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but they're built by living microbial

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colonies of cyanobacteria and on the

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modern earth they're actually found in

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only a very few select places such as

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Shark Bay and in the Caribbean and this

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is because they have to form in very

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hyper saline conditions and I'll talk a

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little more about that here but in the

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Precambrian area they were fairly

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ubiquitous

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all over the planet and they may date

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back all the way back to the Ark

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so there's some of the earliest forms of

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life that we see on the planet that we

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actually have like really nice records

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of and so the way these things form

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cyanobacteria are these photosynthetic

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species so they need to be able to get

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sunlight to grow but you get these mats

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of cyanobacteria and then they form on

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the shallow waters the deepest been

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found about 14 meters or 45 feet but as

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they do that they build up this mucus

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layer that can trap sediment or they can

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precipitate calcite as well but as that

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happens then they grow up through that

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layer and they start a new mat and then

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they grow out and then they collect more

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sediment and then they get another layer

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and they grow up through it and then

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they start another layer and they do

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this over and over again and so they

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trap a lot of the interesting material

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so they tell us a lot about what the

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conditions were when they were growing

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what was available what was settling out

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in the oceans but it's important that

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they need to be free of any sort of

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grazing species so if anything eats them

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then they can't build these rocks that's

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very problematic in today's oceans

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however pre-cambrian there weren't any

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fish or anything eating them so we have

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a lot of them around and you get them in

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all sorts of really interesting

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structures from domes to columns to

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splitting columns and then the last Rock

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we'll call it a rock iron-sulfur

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clusters think of them as very tiny

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rocks that are important in biology but

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they're made out of unsurprisingly iron

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and sulfur and they come in a really

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wide variety of different structures

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depending on how much iron and sulfur

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you have in them anywhere from very

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simple one in two atoms of iron and

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sulfur up to a much larger structures

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but interestingly they're found in a

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number of proteins in biology and

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there's at least three biosynthetic

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systems that have been identified for

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making these things in our biological

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systems and what's really interesting is

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they play a really important role in

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redox oxidation reactions in

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mitochondria

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both complex 1 & 2 an oxidative

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phosphorylation have multiple iron

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sulfur clusters in them they can also

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act as catalytic centers for a lot of

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biological activity and because of this

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they've been suggested as playing an

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important role in the origin of life on

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Earth and so with that I will thank you

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guys for your time and hand things over

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to the experts that are going to be

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giving talks dare I call them the rock