Eventually his controversial analysis was accepted ,and he slowly rose to become one of the leading geologists in the British Isles. He served as a professor at several colleges, and received numerous awards for his work. He is best known for pioneering faunal analysis of Silurian beds by means of index fossils, and his proposal (eventually adopted) that the beds between the Cambrian beds of North Wales and the Silurian beds of South Wales should be assigned to a new geological period -- the Ordovician. This proposal resolved a heated argument over the age of the strata in question.