The Earths Interior.ppt

The Earth’s Interior Prepared by Betsy Conklin for Dr. Isiorho Evidence from Seismic Waves seismic reflection: the return of some of the energy of seismic waves to the earth’s surface after the waves bounce off a rock boundary seismic refraction: the bending of seismic waves as they pass from one material to another, which is similar to the way that light waves bend when they pass through the lenses of eyeglasses The Earth’s Internal Structure crust: the outer layer of rock, which forms a thin skin on the earth’s surface mantle: a thick shell of rock that separates the crust above from the core below core: the central zone of the earth The Crust Mohorovicic discontinuity (Moho for short): the boundary that separates the crust from the mantle Studies of seismic waves have shown that the earth’s crust is thinner beneath the ocean than beneath the continents that seismic waves travel faster in oceanic crust than in continental crust The Mantle because of the way seismic waves pass through the mantle, geologists believe that, like the crust, it is made of solid rock lithosphere: the outer shell of the earth that is relatively strong and brittle, made up of the crust and the upper mantle asthenosphere: a region of the earth’s mantle that is of indeterminate thickness, behaves plastically, and is beneath the lithosphere The Core P-wave shadow zone: the region on the earth’s surface, 103o to 142o away from an earthquake epicenter, in which P waves from the earthquake are absent the way in which P waves are refracted within the earth’s core suggests that the core has two parts, a liquid outer core and a solid inner core The Core (cont.) S-wave shadow zone: the region on the earth’s surface (at any distance more than 103o from an earthquake epicenter) in which S waves from the earthquake are absent The S-wave shadow zone seems to indicate that S waves do not travel through the core at all, if this is true, it implies that the core of the earth is a liquid, or at least a