American geologist, born at Rochester, NY, on the 6th of May 1843. In 1869 he was attached to the Geological Survey of Ohio and in 1879 he became a member of the United States Geological Survey, being engaged on parts of the Rocky Mountains, in Nevada, Utah, California and Arizona. He is distinguished for his researches on mountain-structure and on the Great Lakes, as well as on glacial phenomena, recent earth movements, and on topographic features generally. His report on the Geology of the Henry Mountains (1877), in which the volcanic structure known as a laccolite was first described; his History of the Niagara River (1890) and Lake Bonneville (1891—the first of the Monographs issued by the United States Geological Survey) are specially important. He was awarded the Wollaston medal by the Geological Society of London in 1900. He died at Jackson, MI, on the 1st of May 1918. Among his latest writings were The Transportation of Déris by Running Water (1914) and Hydraulic Mining in the Sierra Nevada (1917).