welcome back 250 whiners it's me again professor Sullivan right in my class I know that the first thing that's probably popping into your mind is that this is an Ozzy Osbourne shirt it's not a Black Sabbath shirt you know I get it you're like how long can he keep this whole black side that shirt gag thing going will you wear for my life I only have so many Black Sabbath shirts but Ozzie Osborne was the singer for Black Sabbath for all of their awesome albums and then then do came in and it was fine but Ozzy is the Black Sabbath and I like so this is still it's still related it's going with the theme a Black Sabbath and the beginning rate of the heavy metals and the beginning of the course so this is I think going to be a shorter video although you'll notice one of the recurring themes besides Black Sabbath shirts in this course will be me saying I think this is going to be a short video and then and that it doesn't but this this one doesn't have too many slides so we'll see how long I blather on for each slide but it looks like it will not be a very long video at least not a very complicated video you I'm recording this now live obviously you already know how long it's going to be because it's already posted so you can see how long it is anyway but we'll see we'll see you at the end of the video we'll see how long this actually was I'm going to set a timer see how long this video is okay so this this section of the chapter and also this video is functioning as an introduction to broadest properties of the earth really just the different layers of the earth and so we you can see here the result of some of the things that happen those different layers and so we have a nice picture of a big nice wave that's clearly happening at the surface of the ocean we have a beautiful picture of a hydrothermal vent from LA basin this one would actually be called a white smoker there's also a black smokers where the smoke is darker color and it's related to the temperature of the bench the higher the temperature the darker this material so this is something that would happen at a mid-ocean ridge or possibly also at a hot spot both features that we'll talk about when we talk about geological oceanography so and then this does anybody know where this is when you're looking at this do you hear John Williams music playing in the background are you imagining being chased around by transverse wrecks or a velociraptor this is a picture of kawaii which is where the at least some of the Jurassic Park movies were made in John Williams for the Jurassic Park movies that's why I made that horrible joke but this is also so this is Hawaii is made by hot spot plumes and so we'll talk about that that's a property of the earth and this is also actually this is a big giant Canyon that is basically the Grand Canyon of Hawaii it's really beautiful I forget I forget actually where it's called but I was there and I took that picture this beautiful quite amazing if you get out there really really amazing a beautiful place so we are going to start off talking about the layers of the earth and there's two different ways to think about this chemical and also physical so start off talking about chemical on this particular figure which does come out of your textbook on one side we have the chemical version and on the other side we have the physical version so on the chemical side and something to keep in mind when you're looking at this picture so up here is the surface and clearly this is where we are we're not below the earth the closer to the center of the earth that you go the denser that the materials get right because the less dense they are they are gonna come they're gonna basically settle by density and the less dense things will be at the surface and the more dense things will settle to the bottom and so starting from the surface and going down we have at the top we have the crust the crust is thin compared to the other layers of the earth it's between four and sixty kilometers and that range is because it depends on where you are on the crust and so the crest goes the ocean crust it also includes the Continental crest and so if you're somewhere where there is mountains then the crest will be thicker than if you're somewhere where there is not and that that's why it can be a range of kilometers it has the lowest density minerals the minerals that make up the crust are silicates silicates which are primarily composed of iron and silica the silicates in the ocean are largely the salts we'll talk about this in the next few slides down the road and the silicates that make up the continental crust are primarily Granite's going deeper into the earth the next layer that we have is the mantle so we have a crust at the surface below the crust is the mantle the mantle is much thicker than the crust it's about 2,800 kilometers thick and it has higher density minerals made largely of iron and magnesium right so we have silt we have iron in both of these what we've substituted out the iron I'm sorry the silica in the crustal materials for magnesium in the mantle materials and then and and so the the crust is this layer here that has this mountain range as well as the oceans floor and then below that we have the mantle made out of silicate materials richer an iron and magnesium and finally the center of the earth or the I guess you could say the deepest layers would core mm-hmm which is the thickest layer not by a huge amount but it's 3,500 kilometers from kind of the edge of the core to the center and it is the highest density minerals again iron is the common theme here but instead of magnesium which is in the mantle or silica which is on the crust in the core we have nickel so the core is mostly iron and nickel with a little bit of sulfur so crust mantle core and this is how we would to find them chemically I'm telling you of a different there's iron in all of them and then either so it cut magnesium or nickel as you get deeper and deeper and again this is all related to density on the flip side we can think about things more in a physical manner and so if I was talking about these physically I might talk about the lithosphere the asthenosphere the mesosphere and then the outer and inner core hate teacher secret after this section of the book we're never going to talk about the Mises here or outer inner core but we will talk about the asthenosphere and the lithosphere a little bit so the Lissa's lithosphere is the shallowest and and includes parts of the crust in the upper mantle it's a cool rigid and brittle like the seafloor when you're not in your hydrothermal vents or volcanoes below the lithosphere so that's this upper layer right here again the the crust all of the crust and the upper part of the mantle the asthenosphere is the next deeper section it's warm and plastic plastic means it will flow think of it like warm glass right or it's something that's molten it'll it'll flow very slowly it's not like running water but it it will flow and the asthenosphere right here is the upper mantle the so again the lithosphere goes down to about 100 kilometers so a little deeper than what we call the crust if you remember from this last slide I sent across about 60 kilometers if you're looking at the lithosphere describing it that way it's about another 40 kilometers so you have the upper 40 kilometers of the mantle which is 2,800 kilometers so just a tiny slice off the top and then the asthenosphere below that is about 700 kilometers and then below that we have the lower mantle middle lower mantle this is an area called the Mises sphere it's a little more rigid due to the higher pressure so that chemically these two are similar the asthenosphere that the mesosphere remember iron and magnesium is primarily what's making up these rocks but as you're getting deeper and deeper into the earth below the surface the pressures are getting greater and greater and greater and so there's a transition a certain point between the asthenosphere and mrs. fear means this year where the Mises fear is much more rigid because there's a lot more pressure and so it keeps keeps it all right keeps it like tight and compact and rigid as opposed to so Yunus dear that's the Inner Sphere which is a little more plastic and then finally we have the outer core and the inner core the outer core is liquid the inner core is not the inner core is rigid due to super duper ultra mega weigh super high-pressure outer core is liquid and the common thought is that the Earth's magnetic the reason we have magnetosphere on earth is because of the I think iron moving in the outer core that's something you'll have to ask your favorite geologist friend maybe one of the ringers that's in this class that is gonna slay the first part of this of course but um those are so those are the layers of the earth if you think about it in a physical manner the reason that you should know these things is because you lithosphere floats on the asthenosphere so remember lithosphere is the shallowest section closest to the surface including the surface and the asthenosphere is just below it so this fear oops sorry run direction the lithosphere is floating on the asthenosphere and this is ultimately this is why we have continents moving around right and in addition to plate tectonics this is why the place where I'm moving around and the continents are on the plates excuse me I should have brought water I'm looking around I should have brought water I did not bring water to this cellar that I recorded wherever it happens to be and George's puts bring me water but he didn't and so I'm a little parched sorry sorry about my voice so sorry about that little diversion now let the steerer floats on the asthenosphere and we have a continents and the ocean on are both part of the lithosphere the continental crust like I mentioned is largely made up of a rock a silicate rock called granite which has a density this is the density right here of 2.7 grams per cubic centimeter oh my that's an error right there it should be per cubic centimeter that that centimeter thing should be to the negative three grams person in here Wow the oceanic crust is made up primarily of basalt which is three grams per cubic centimeter a little bit a little bit more dense than the continental crust this difference which is actually ten percent so the the granite is ten percent less dense than basalt that has a really big implication Mellisa sphere includes the crust both types in the continental and oceanic and the upper part of the mantle as I mentioned about 40 kilometers of that mantle and the lithosphere generally or I'm sorry literally which is more than generally literally floats on the mantle which is why plate tectonics occurs yeah I got a little head of myself right the the lithosphere is moving on the asthenosphere and that movement of the parts of the lithosphere is what plate tectonics is and we'll get into this in this slide so here we have a picture of the kind of surface of the earth and we have the lithosphere here it's an upper mantle oceanic crust continental crust and then the asthenosphere here in the upper mantle down another 670 kilometres according to this picture sure that's 100% accurate the important part to remember here is that the oceanic crust a little bit denser more dense it's thinner than the continental crust the continental crust is a little bit less dense but it's actually thicker than the oceanic crust because the oceanic crust is more dense than the continental crust what happens when they meet will you tell me you tell me to 51 hours what happens what happens when they meet now you know what I'm gonna actually I'm gonna walk away no Matt maybe I will walk away just over here well you tell me oceanic crust continental crust if you look at that picture what happens when they meet and why come back into the picture oceanic crest is more dense if it's more dense it's gonna go underneath the continental crust because the continental crust will float a little bit higher than the oceanic crust so when they meet continental crust oceanic crust more dense goes underneath right and this is why ladies and gentlemen Aggies of all ages this is why the oceanic crust is younger always younger than the continental press because whenever the two of them meet oceanic crust loses oceanic crust can never destroy continental crust that's always gonna go underneath it continental crust when it meets other continental crusts you get mountains and that's how you can describe right he got things like the Himalayas in the house wait and the Rocky Mountains Wow whoa no I take it back and not even I'm not sure the Alps I'm not sure if that's continent continent but the Himalayas right the Indian subcontinent crashing into the the Asian or the rest of the Asian continent that's continent meaning continents and one can't subduct against the other since they're pretty similar pretty much the same density and so they basically collide and make a mountain range oshi and oceanic crust is always gonna lose and go underneath okay so that's that's important to remember and then this whole system is floating on the asthenosphere this whole system with the content of an oceanic crust in the upper part of the mantle is the lithosphere and that's floating on the asthenosphere so and you're saying to me a plastic solid over which the crust can float professor Sylvan that's crazy it's not crazy that's not crazy a good comparison for this for this for the asthenosphere is that silly putty's right so think of the asthenosphere down here as silly putty it's a solid right definitely a solid but you can mold it you can imagine if you have silly putty right you can if you put stuff on top of it and you push it you can imagine it moving along with the silly putty imagine objects of like different densities such as maybe I'm just throwing this out there this is totally random but let's say oceanic crust in the continental crust floating huh Brit and the ocean crust floating deeper in this silly putty than the continental crust because it's more deaths alright and it's going to be it's gonna push down gravity's gonna make it push down a little more on that so that's this is this is basically the best analogy I have for that so I have the things that I want you to remember oceanic crust continental crust they're all part of the lithosphere as is the upper part of the mantle oceanic crust is denser because it's made of basalt which is three grams big centimeter there should be a negative there and ran it is making up most of the continental crust it's about ten percent less dense 2.7 grams per cubic centimeter at 10 percent less dense than the oceanic crust and so when the two of them meet but floating on the asthenosphere but the oceanic crust will float a little deeper and go underneath the continental crust and we can talk about that more later in the chapter but that's what I want you to remember for now and that true to my word this is that is the end of this particular section this is not a terribly long one and in the last part of this chapter we will talk about isostasy and so doing pretty good 251 hours you've been keeping up with me you've been putting up with my crazy shirts hopefully you're with me that Ozzy Osbourne and Ozzy Osbourne shirt fits with a Black Sabbath theme but that's that's really up to you if you buy it and that's the end of this lecture I will see you in the next lecture when we talked about isostasy but for now just remember asthenosphere is and lifteth spheres and crusts and mantels and Granite's and basalts these are the things that I want to remember don't be scared it's all good for you and I will see you I'll see you in the next lecture see you then until then have fun and read the book read the book and I'll see you later bye