The Geological Map Of England, Wales And Part Of Scotland, by J. & C. Walker, was based on William Smith's famous map entitled "A Delineation of The Strata of England and Wales with part of Scotland; exhibiting the Collieries and Mines; the Marshes and Fen Lands originally Overflowed by the Sea; and the Varieties of Soil according to the Variations in the Sub Strata; illustrated by the Most Descriptive Names" (W. Smith, Augst 1, 1815).

For more information read Simon Winchester's fabulous biography "The Map That Changed The World".