Roderick Impey Murchison (1792-1871), Scottish geologist and geographer. Following his military career he became a member of the London Geological Society, and, in 1855, its president. Murchison published the Silurian System in 1839, which was the first stratigraphic system defined by fossil content rather than lithology (rock features). Following geological tours of Scotland, Russia and Germany, he established the Devonian and Permian systems geological dating. Leaving geology, he become head of the Royal Geographical Society, where he encouraged British exploration around the world. He was knighted in 1846. Engraving from The Year-Book of Facts 1856.