Presentation on theme: "Layers of the Earth Notes"— Presentation transcript:
1Layers of the Earth Notes Taken from:Article from Cate ‘ O Donnell 2012
2IntroductionScientists have only understood the composition of the Earth for about the past 100 years. It wasn’t until the modern seismograph was invented that they had the tools to explore the different layers of the Earth. (A seismograph is a device used by scientists to study earthquakes.)
3Main LayersThe Earth is made of 3 basic layers:CrustMantleCore
4The CrustThe crust is the least dense, thinnest and outermost layer of the Earth.The Earth’s rocky outer curst solidified billions of years ago, soon after the Earth formed.It is made of oxygen, silicon, aluminum.
5The Crust Types of Crust Layer Description Density Composition LocationContinental CrustMakes islands and continentsOlderLess dense when compared to oceanic crustHas less amount of iron, calcium, and magnesiumLess dense granitekilometers(Thick)Oceanic CrustFound under the oceanYoungerDense when compared to continental crustHas twice as much iron, calcium, and magnesiumMore dense basalt5-10 kilometers(Thin)
6The CrustThis crust is not a solid shell. It is broken up into huge, thick crustal or tectonic or lithospheric plates that drift on top of the soft, underlying mantle. This layer where you see plates is called lithosphere.
7The MantleThe mantle is the layer of Earth between crust and the core.It is over 20,000 kilometers deep and makes up most of the Earth’s mass.It has more magnesium and less aluminum and silicon than the crust.The mantle is denser than the crust.(Humans have never been to the mantle, but a group of scientists in the middle of the Pacific are trying to change that. They are planning on drilling a hole into the thinnest part of the crust under the ocean. This complicated endeavor will involve six mile long drilling pipes and drill bits that have to be changed every fifty hours. It is estimated that the project could reach the mantle in the early 2020s.)
8Mantle Layers Upper Mantle Or Aesthenosphere Physical state of Matter Liquid magmaLower MantleMesosphereSolid rock
9Convection Currents:Because the core is so hot, a current of heat flows from the core to the crust.These currents are called convection currents.Convection currents take place in the mantle.Convection currents cool down as they come closer to the surface of the Earth.The rising of the current stops and it travels in a horizontal direction along the bottom of the crust.When the current cools down more, it falls back towards the core.There, the temperature increases and the current rises again. This process goes on and on.
10The Core Composition Thickness State of Matter and CompositionThicknessState of Matter andReason for state of matterOuter Coreiron, nickel, sulfur, and oxygenabout kilometers thickLiquidBecause they have melted in the intense heat of the outer coreInner Coremainly of iron and nickelaround kilometers thickSolidBecause of the high pressure exerted on them by the outer layers of the Earth
11The Core(The outer core was discovered by seismologist Inge Lehmann from Denmark. A seismologist is a person who studies earthquakes. By looking at the way earthquake waves moved through the Earth, Lehmann was able to determine that the outer core was liquid.)Seismic waves move much more slowly through liquids than solid rocks. They are also reflected instead of moving in a straight line as they do through solid materials.