Sir Charles Lyell (1797-1875), British geologist. He was born near Dundee, Scotland, and was educated at Exeter College, Oxford. He graduated in classics, then took up law as a profession. His private interests turned to geology, by 1823 he was secretary of the Geological Society. With failing eyesight, he became a professional geologist. In 1830-33 he published the three volume work "Principles of Geology", using his own observations to develop the doctrine of uniformitarianism of James Hutton - the idea that the Earth was fashioned by the same forces that exist today. He explained the causes of earthquakes, of the gradual building of volcanoes and contributed greatly to stratigraphy. A close friend of Darwin's, he was one of the first to suggest the Earth was more than 300 million years old. He is remembered in the names of many mountains and in craters on the Moon and Mars.