British geologist born in 1785 and died in 1873, which characterized the Devonian and Cambrian systems, and made important contributions to structural geology.
He attended college at the University of Cambridge, a place where the rest of his professional career, which culminated in 1818 to occupy the Chair of geology. His studies on the fossil fauna and stratigraphy of the present outcrops North Wales, allowed in 1835 a series of Stratigraphic divisions, to the lower of which was baptized with the name of Cambrian system. At the same time, his friend Murchison realized their works in outliers present in the South of Wales, which defined the Silurian system. Along with Murchison he defined later in the southeast of the country the Devonian system, and in 1841 they were together an expedition to Russia, after which defined the Permian system on the basis of the outcrops in the area of Perm.
The existence of strata which overlap northward with the unit proposed by Sedgwick and South defined by Murchison, generated a discussion between both scientists to determine which system they belonged. The discussion is prefaced for several decades, but the solution to this problem were found until years after his death, when in 1879 C. Lapworth proposed a new intermediate system between the Cambrian and Silurian baptized with the name of Ordovician.