Clarence King (1842-1901) was an American geologist and mountaineer. First director of the United States Geological Survey from 1879 to 1881, he was noted for his exploration of the Sierra Nevada. In 1867, King was named U. S. Geologist of the Geological Exploration of the Fortieth Parallel. He spent six years in the field exploring areas from Wyoming to the border of California. During that time he also published his famous Mountaineering in the Sierra Nevada (1872). After the completion of the field work, in 1878 he published Systematic Geology.