While still a student, he became interested in botany and natural history, and his attention during visits to Gloucestershire was drawn to the fossils found there. He began to form the great collection, for which he is known. He published "An Essay toward a Natural History of the Earth and Terrestrial Bodies, especially Minerals, &c." in 1695 (2nd ed. 1702, 3rd ed. 1723), followed by "Brief Instructions for making Observations in all Parts of the World" (1696). He later wrote "An Attempt towards a Natural History of the Fossils of England" (2 vols., 1728 and 1729). In these works he showed that the stony surface of the earth was divided into strata, and that the enclosed fossils were originally generated at sea; but his views on the method of rock formation remained unsupported. They were satirized by John Arbuthnot, who ridiculed what he saw as Woodward's classicist method and personal venality. Nonetheless, Woodward accurately described his rocks, minerals and fossils in his elaborate "Catalogue".