CD740: Plate Tectonics

Claim CD740:

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Response:

1. Plate tectonics was uncertain as recently as the 1960s, but evidence in its favor has become overwhelming:
   • Plate motions are measured directly (Davidson et al. 1997).
   • The eastern edge of the continental shelves of North and South America fit closely (within 50 km) with the western continental shelves of Africa and Europe (Bishop 1981). The Mid-Atlantic Ridge has the same shape.
   • Plant and animal fossil distributions, geological formations, and indications of ancient climate match up in Africa and South America as if the continents once fit together (Davidson et al. 1997).
   • When new rocks are formed, they record the earth's current magnetic field, which reverses occasionally. The magnetic field pattern recorded in the sea floor rocks shows bands mirrored across a spreading center (Bishop 1981; Davidson et al. 1997). (See also Magnetic reversals.)
   • Paleomagnetic studies show different polar wandering on different continents, indicating that the continents moved relative to one another (Bishop 1981; Davidson et al. 1997).
   • Oceanic sediments are young and thin, indicating that sea basins are relatively young (Graham 1981).
   • Maps of earthquake locations show plate boundaries and the paths of subducting plates (Davidson et al. 1997; Graham 1981).
   • Hot spots leave trails such as volcanic island chains as the plates move over them (Davidson et al. 1997).

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