While engaged in levelling for a proposed canal in Gloucestershire, the idea of a general law occurred to him relating to the strata of that district. He conceived that the strata lying above the coal were not laid horizontally, but inclined, and in one direction, towards the east; resembling, on a large scale, “the ordinary appearance of superposed slices of bread and butter.” The correctness of this theory he shortly after confirmed by observations of the strata in two parallel valleys, the “red ground,” “lias,” and “freestone” or “oolite,” being found to come down in an eastern direction, and to sink below the level, yielding place to the next in succession. He was shortly enabled to verify the truth of his views on a larger scale, having been appointed to examine personally into the management of canals in England and Wales. During his journeys, which extended from Bath to Newcastle-on-Tyne, returning by Shropshire and Wales, his keen eyes were never idle for a moment. He rapidly noted the aspect and structure of the country through which he passed with his companions, treasuring up his observations for future use. His geologic vision was so acute, that though the road along which he passed from York to Newcastle in the post chaise was from five to fifteen miles distant from the hills of chalk and oolite on the east, he was satisfied as to their nature, by their contours and relative position, and their ranges on the surface in relation to the lias and “red ground” occasionally seen on the road. The general results of his observation seem to have been these. He noted that the rocky masses of country in the western parts of England generally inclined to the east and south-east; that the red sandstones and marls above the coal measures passed beneath the lias, clay, and limestone, that these again passed beneath the sands, yellow limestones and clays, forming the table-land of the Cotswold Hills, while these in turn passed beneath the great chalk deposits occupying the eastern parts of England. He further observed, that each layer of clay, sand, and limestone held its own peculiar classes of fossils; and pondering much on these things, he at length came to the then unheard-of conclusion, that each distinct deposit of marine animals, in these several strata, indicated a distinct sea-bottom, and that each layer of clay, sand, chalk, and stone, marked a distinct epoch of time in the history of the earth.