The Depersonalization of Geology

Some historians have concluded that plate tectonics caused a change in the standards of the geological community, but the shift in standards of the American scientific community was not so much the result of the development of plate tectonics as it was a larger trend that helped to cause it. Geologists consciously chose to move their discipline away from observational field studies and an inductive epistemic stance toward instrumental and laboratory measurements and a more deductive stance. This shift helps to explain why geologists felt compelled to attend to the demands of geodesists even at the expense of their own data: it was the geodesists’ data, rather than their own, that seemed to be in the vanguard of their science. Geologists at the start of the twentieth century had high hopes for their discipline, and they were not disappointed. The Carnegie Institution’s Geophysical Laboratory became one of the world’s leading locales for laboratory investigations of geological processes, and work done there inspired scientists at other American institutions. At Harvard, for example, Reginald Daly joined forces with Percy Bridgman to raise funds for a high pressure laboratory to determine the physical properties of rocks under conditions prevailing deep within the earth. The application of physics and chemistry to the earth was also advanced at the Carnegie’s Department of Terrestrial Magnetism, where scientists pursued geomagnetism, isotopic dating, and explosion seismology.’ By mid-century, the origins of igneous and metamorphic rocks had been explained, the age of the earth accurately determined, the behavior of rocks under pressure elucidated, and the nature of isostatic compensation resolved, largely through the application of instrumental and laboratory methods. Similar advances occurred in geophysics and oceanography. The work that Bowie and Field instigated in cooperation with the U.S. Navy, and that scientists at places like Wood’s Hole and the Scripps Institution of Oceanography greatly furthered, had grown by the 1950s into a fully fledged science of marine geophysics and oceanography with abundant financial and logistical backing. This work —in gravity, magnetics, bathymetry, acoustics, seismology— relied on instrumentation, much of it borrowed from physics.