EAR 105 Lecture Notes - Lecture 3: Emil Wiechert, Geothermal Gradient, Seismic Wave
16 Sep 2016
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Document Summary
These layers are subdivided on the basis of seismic waves. As you go deeper into the earth, it gets hotter and pressure increases. Change with depth: pressure (p) of overlying rock. Temperature (t) increases from heat generated deep within earth"s interior. The rate of t changes with depth. Finding density - a plumb bob is deflected by a nearby mountain mass (gravitational effect of that extra mass) Degree of deflection can be used to calculate earth"s mass. The density from this method (4. 5 g/cm^3) is much higher than the density of the thin outer crust (2. 5 g/cm^3) This suggests that density must increase with depth. In 1896, emil wiechert made important contributions. Determined that metal must be present in earth"s interior. Deduced that the metal must occur at the earth"s center. Presence of magnetic field is the key for us to learn about liquid alloy. We know there is a liquid part of the core because of seismic waves.
