Geologist, born at Edinburgh; at the age of 20 he joined the Geological Survey of Scotland, and in 1867 became director; in 1870 he became Murchison professor of Geology at Edinburgh, and in 1881 was appointed chief director of the Geological Survey of Great Britain; in 1801 he was knighted, and from 1892 to 1893 was President of the British Association; he is the author of various works on geology, written with great lucidity, as well as essays much appreciated; b . 1835.