Adam Sedgwick (22 March 1785 – 27 January 1873) was one of the founders of modern geology. He proposed the Devonian period of the geological timescale. Later, he proposed the Cambrian period, based on work which he did on Welsh rock strata.Though he had guided the young Charles Darwin in his early study of geology and continued to be on friendly terms, Sedgwick was an opponent of Darwin's theory of evolution by means of natural selection.