so this is the PowerPoint we had a class for the Earth's layers what are the main characteristics of the Earth's layers and how can the Earth's layers be illustrated those are the two main things you need to know for this quiz first crust is the outer layer of the earth similar to the skin on an apple made up of both continental and oceanic crust five to fifty kilometers thick oceanic crust a thin layer of crust that overlies the ocean basins more dense than continental crust mostly basalt rock thinner than continental crust it is five to ten kilometers thick younger than continental crust because it is constantly renewing itself along ridge lines there is something in the mid-atlantic called the mid-atlantic ridge that is I think it's like 2 centimeters a year know that it's producing new crust continental crust layer rock which forms the continents but it's less dense than oceanic rock mostly granite thicker than oceanic crust remember that density it's very important it's less dense so that's why it's like higher up it floats on top when you get to plate tectonics that's something that you'll want to know about older than oceanic crust class Earth Earth's layers the lithosphere mm-hmm it's the solid outer section of the earth which includes the crust and also includes the cool dense rigid upper part of the mantle so I saw written somewhere in our labs that the lithosphere and the asthenosphere our various kinematic layers they are defined by their movement or lack of movement the asthenosphere is the solid part of the upper mantle weaker less rigid plasticity like silly putty so that's really its defining characteristic crust moves over the plastic like asthenosphere these plates crash into each other here the oceanic crust is subducting under the continental crust which creates volcanoes so this is where you had to copy this down do your best to remember these these parts all right these are the mantle slides largest layer of the earth under the crust about two thousand eight hundred ninety kilometers that's hard for you to imagine remember how big one meter is a pillow meter is one thousand of those just one so this is nearly three million meters under the crust which is only five to twenty kilometers thick composed of silicate rocks rich in magnesium and iron intense heat causes the rocks to rise and cool and sink like a lava lamp or hot air balloon the process is called convection which causes the crust to move convection currents something we talked about in our laps average temperature 3,000 degrees Earth's layers the outer Kerr core liquid layer magma 2300 kilometers thick it's the second largest layer not as large as the mantle composed of liquid iron and nickel lies between the inner core and the mantle because the magma moves around the inner core Earth's magnetic field is created think about rubbing a piece of iron on a magnet you can magnetize it that way cool no I didn't say average temperature 4,000 to 5,000 degrees inner core solid ball of metal because of the intense pressure remember that solid not liquid liquid like the outer core solid because of pressure those are important 1250 kilometers thick made of solid nickel and iron so odd it melts everything in the outer core spins at a rate faster than the earth rotates and it's the densest layer of the earth it's the densest layer that's why it's there if it wasn't as dense it as is it would not be there it's dense it's very dense density density something you need to know about it's the amount of material that you can fit into a given space and the inner core is the densest layer average temperature 5000 degrees to 6,000 degrees what our seismic waves waves of energy caused by earthquakes and other rock movement travel through some layers of the earth recorded with seismographs seismic waves are used to determine which layers of the earth are solid or liquid some seismic waves cannot pass through certain layers giving us a clue to the layers composition let's go back to that see here I think there's a pointer thing there we go all right so remember ok so S waves or secondary waves the black ones P waves primary waves are the yellow ones remember secondary waves cannot pass through liquid do you see this the liquid outer core is blocking these s waves these second airy waves the p-wave shadow zone look at that can't see anything so if we were recording here I'm this part of the earth you would see something here you would expect to see something here but you can't you would expect to see something here but you can't you would expect to see something here but you can't but what we do see are these secondary waves and we can tell using using trigonometry that they have been bent and curved if you think about sound passing through water versus on the surface of the earth it's different it's being bent this is an exactly like sound but it's similar concepts the speed at which they move does change I think some of the reason why they Bend actually is because of the way that material rotates anyway that's just complete conjecture well yeah so the primary ways the S waves can go through different materials the primary waves can pass through solid and liquid but they are bent secondary waves again cannot pass through liquid but they can pass through solid okay can you list the characteristics of each of the Earth's layers it's very important let's just do a little rundown here I'll get my pointer again inner core solid caused by pressure the densest layer its iron and nickel composition the outer core is iron and nickel composition also but it's liquid and what were these like six thousand degrees was the inner core and like four thousand degrees it was the outer core and then like three thousand degrees was the mantle the mantle is where you find magma it's also where you have convection currents they go in these circles so when you have material that's here close to the outer core it gets hot and Rises and it cools when it's towards the surface and then it sinks because material is actually becoming less dense when it gets hot so Rises and it cools it gets more dense because it's cooling so it sinks what were the primary elements in the mantle I think it said in this slide it was like magnesium silicates leave there's also a lot of LUMO there's even magnesium in the core but not as much as iron nickel so just like magnesium silicates and and in the crust of course crust we have two main types of crust oceanic crust and continental crust oceanic crust is made of basalt and is more dense than continental crust which is made of granite area illustrate the layers of the earth I'm not gonna do that you can do that that's it good luck on your test just or in your quiz if you understand this material you will do well on the test and where's my stop button