Presentation on theme: "Journey to the Center of the Earth"— Presentation transcript:
1 Journey to the Center of the Earth Topic 12Regents Earth Science
2 Objectives Describe the Earth’s internal structure. Explain the changes in P and S wave velocities in the Earth.Describe the shadow zone and explain its significance.Use the ESRT to describe various properties of the Earth’s interior such as pressure, temperature, and density.
3 The study of seismic waves allows scientists to “see” inside the earth. Scientists have discovered that seismic wavesrefractreflectchange velocityand become absorbed by various parts of the Earth’s interior
4 Changes in the speed of seismic waves were used to determine the location of the Earth’s different layers
5 Layers of the EarthCrustMantleOuter CoreInner Core
6 Crust This is the layer that we live on The thickness ranges from 8 km under the oceans to 40 km under the continentsContinental crust is thickest beneath high mountainsIt is the thinnest layer of the earth
7 Comparing Oceanic and Continental Crust Oceanic CrustComposition is “basaltic”Density about 3.0 g/cm3Younger (180 my old or less)Continental CrustComposition is “granitic”Density about 2.7 g/cm3Older (4 by old)
8 Mohorovicic Discontinuity Called MohoIs the boundary between the crust and mantleWas discovered in 1909 by Andrija MohorovicicHe found that seismic waves increase in speed at an average depth of 40 km.
9 The Mantle It consists of magnesium, iron, and silicon Is divided into 2 regionsIt consists of magnesium, iron, and siliconIt is 3000 km wideIt is more rigid closer to the surface
10 The Upper Mantle Rigid Mantle Plastic Mantle Cool and brittle The rigid mantle and crust make up the lithosphereDivided into sections called plateskm thickPlastic MantlePartially molten - the rock in this layer has the ability to flow.Also known as the asthenosphereMagma originates hereAbout 200 km thick
11 The Outer Core liquid 2100 km wide consists of nickel and iron flow of iron creates the Earth’s magnetic field
12 How do we know the outer core is liquid? S-waves do not pass through this zoneShadow zone - no p-waves or s-waves received here103° to 143° from focus
13 At the outer core Thers is a sudden decrease in p-wave velocity and S-waves disappear
14 The Inner Core solid consists of the metals nickel and iron temperature is 6,000° Cwidth = 2,100 km
16 Selected Poperrties of the Earth’s Interior The x-axis shows the depth from bottom to top.As depth increases, pressure increases.1 atmosphere = 14.7 psi or “normal” air pressure at sea levelAs depth increases, density increases.
17 Melting Point and Temperature As depth increases, temperature increases.What evidence can you see for a liquid outer core?