In 1831 he went to the England–Wales border, to attempt to discover whether the greywacke rocks underlying the Old Red Sandstone could be grouped into a definite order of succession. The result was the establishment of the Silurian system under which were grouped, for the first time, a remarkable series of formations, each replete with distinctive organic remains other than and very different from those of the other rocks of England. These researches, together with descriptions of the coalfields and overlying formations in South Wales and the English border counties, were embodied in "The Silurian System" (1839). English naturalist, geologist, and palaeontologist, John William Salter assisted Murchison in his work on Siluria (1854 and later editions).