please answer all three. thank you 1) What is the geomagnetic time scale and how
ID: 117767 • Letter: P
Question
please answer all three. thank you
1) What is the geomagnetic time scale and how was it developed? Be sure to discuss properties of the Earth's magnetic field and the rocks that record the field that allowed this time scale to be developed, as well as the impact that the time scale had on the beginning of the theory of plate tectonics 2) What is the principle of isostacy? Explain what is meant by isostatic equilibrium, and sketch the Airy vs. Pratt models for isostacy beneath mountain belts 3) What is heat flow? Describe why measuring heat flow is a valuable probe of the structure of the lithosphere.Explanation / Answer
SOLUTION:-1.
Geomagnetic time scale is one of the subdivisions of geologic time scale. it is related to earth magnetic field.The terms refer to the direction of earth's magnetic field. The earth has a field very much like a standard bar magnet, with a north and a south magnetic pole. Unlike a bar magnet, whose field is locked into the solid crystals of the magnet, the earth's field is generated by moving molten iron in the outer core. it was developed by thorough study of rocks from around the world, during which it was observed that rocks from specific time periods contained magnetic minerals whose orientation was opposite to that of the current magnetic field. By comparing the patterns of magnetic reversals with those of rocks of known age, the approximate ages of rocks can be established. This is particularly useful for basalts of the oceanic crust, which record the Earth's magnetic field as they solidify from molten lava symmetrically about the midocean ridges. This motion is very complex and at times, the complexity results in the north and south end of the earth's field trading places. It's as if you turned the bar magnet upside down, but did it without actually moving the bulk of the earth. This happens at time intervals of a few hundred thousand years to tens of millions of years and is not at all periodic.The time scale has been accurately extended back to the Upper Jurassic, the age of oldest existing oceanic crus.
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