Word: crusting
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Harvard Professor of Mineralogy Charles W. Burnham said Hogue was auditing his class, Earth and Planetary Sciences 50, "Materials of the Earth's Crust," last semester...
...evidence suggests that earthquakes are incremental steps in the movement of the 20 or so lithospheric plates that make up the planet's crust. It takes about 50,000 major jolts to nudge a plate 100 miles. Eldridge Moores, the geologist who guides McPhee, believes California was formed when a 2,000- mile-long arc of land parked against North America 250 million years...
...does he know? Moores is a specialist in ocean crust, which he routinely discovers high and dry in the Sierra Nevada. "The whole vast assemblage of transported deep-ocean rock," writes McPhee, "now rests on California like a ship stuck in sand, listing thirty degrees to the west." Scientist and writer poke through the wreckage. They straddle fault lines and sift through road cuts while impatient drivers speed...
According to Professor of Geology Adam M. Dziewonski, hotspots underneath mid-oceanic ridges in the earth's mantle can reach depths of 300 or even 600 kilometers. This suggests that mid-oceanic ridges are active suppliers of crust-forming material, rather than simply passive openings from which hot mass flows...
...analyzing tens of thousands of waves to determine their trajectories and velocities, the Harvard team extrapolated a model of hot and cool spots in the mantle. They were able to prove that hotspots underlying mid-oceanic ridges affect wave speed more than 100 kilometers below the crust, and therefore that the hotspots must extend to such depths, some up to 600 kilometers...