science · 15 May 1841 · 183 years ago
birth
Born 15 May 1841; died 4 Jan 1912 at age 70.
American geologist who coined the term isostasy for his explanation that continents rise higher on the Earth's surface by virtue of their less dense crustal rock; ocean basins are denser material. After the civil war, while still an army officer, from 1875, he assisted in Powell's survey of the Rocky Mountains. From 1880 until his retirement from the army in 1891, he worked for the U.S. Geological Survey (USGS). He made geological investigations of the Grand Canyon in Colorado, the plateaus of Utah, and the 1886 Charleston earthquake. In seismology, he pioneered a method to determine the depth of the focus of an earthquake and the speed of its seismic waves. In 1887, he became the first head of the USGS division of volcanic geology.
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