Clarence Edward Dutton (May 15, 1841 – January 4, 1912) was an American geologist and US Army officer. Dutton was born in Wallingford, Connecticut on May 15, 1841. He graduated from Yale College in 1860 and took postgraduate courses there until 1862, when he enlisted in the 21st Connecticut Volunteer Infantry; he fought at Fredericksburg, Suffolk, Nashville and Petersburg. He was elected as a member to the American Philosophical Society in 1871. In 1875, he began work as a geologist for John Wesley Powell and, after 1879, for the U.S. Geological Survey. Working chiefly in the Colorado Plateau region, he wrote several classic papers, including geological studies of the high plateaus of Utah (1879–80), the Cenozoic history of the Grand Canyon district (1882), and the Charleston, South Carolina, earthquake of 1886. As head of the division of volcanic geology at the USGS, he studied volcanism in Hawaii, California, and Oregon. He helped coordinate the scientific response to a large earthquake in the Mexican state of Sonora in 1887. In 1878, he was one of the ten founders of the Cosmos Club. He was elected a member of the National Academy of Sciences in 1884. In 1886, Dutton led a USGS party to Crater Lake, Oregon. His team carried a half-ton survey boat, the Cleetwood, up the steep mountain slope and lowered it into the lake. From the Cleetwood, Dutton used piano wire with lead weights to measure the depth of the lake at 168 different points. The survey team determined the lake was deep. The currently-accepted maximum depth figure, measured by sonar, is 1,943 feet (592 m). In a footnote to an 1882 review in the American Journal of Science, Dutton coined the term "isostasy". He later stated: "In an unpublished paper I have used the terms isostatic and isostacy (sic) to express that condition of the terrestrial surface which would follow from the flotation of the crust upon a liquid or highly plastic substratum – different portions of the crust being of unequal density." Thus he realised that there is a general balance within the Earth's crust, with lighter weight blocks coming to stand higher than adjacent blocks with higher density, an idea first expressed by Pratt and Airy in the 1850s. Dutton elaborated these ideas in his address to the Philosophical Society of Washington in 1889. When this was printed in 1892 the term isostasy was formally proposed,