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The original announcement by the Society of Arts may have ambitiously required that the completed mineralogical map be produced 'on or before the first Tuesday in February, 1804’, however it was not until February 1815 that William Smith finally submitted his map and was awarded the 50 guinea premium for his efforts.
The Map, ‘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 substrata, illustrated by the most descriptive names', was finally issued to the public in September 1815 (although confusingly all copies of the map are marked August 1815) with a dedication to his patron, Sir Joseph Banks on the title sheet. It was published by John Cary, one of the top cartographers of the day, on a specially commissioned base map which removed the county boundaries and much of the topography to show the geology better.
The colouring, the most sophisticated use of Smith’s ‘fading technique’ so far, is explained in the accompanying Memoir:
"The courses of the strata, or the length and breadth of surface occupied by each, as they rise successively from the level of the sea, on the eastern to the western side of the Island, are represented by colours.
The edges of the strata, which may all be crossed in journey from east to west, are called their outcrops; and the under-edge of every stratum, being the top of the next, and that being generally the best defined, is represented by the fullest part of each colour….
The colours, though brighter than those they represent, are in some degree assimulated to the colour of each stratum, except the chalk, which being colourless seems best represented by green, as strong colours are necessary, and there being no stratum of equal extent which required that colour....In this mode of representing the strata by colours, various insular, or detached parts of the same colour may be observed.”
That is Smith chose colours which were nearest in hue to the natural strata he was depicting. The lower, older edge of each outcropping rock stratum was coloured darker in tone fading as the rock stratum becomes younger towards the upper edge.
The Map was, like his proposed first publication, to be of utility to industry, agriculture and the arts:
“…the most proper soil will be known for plantations of timber; miners and colliers, in searching for metals and coal; builders for freestone, limestone, and brick-earth; the inhabitants of dry countries for water; the farmer, for fossil manures; will all be directed to proper situations, in search of the various articles they require; and will be prevented from expensive trials, where there can be no prospect of success.”
Produced at a scale of 5 miles to the inch, the Map measured (when joined) 259cm x 176cm and could be purchased in a variety of formats:
15 individual sheets, with index and Memoir - £5 5s
Joined, then mounted on canvas and rollers - £7
Ditto and also varnished - £8
Travelling edition (joined but split into three folding sheets in a case) - £7
Joined, mounted and on spring rollers - £10 Ditto and varnished - £12
The methodology of producing such an ambitious map was problematic, not only because applying the fading colouring technique was time consuming but each would be slightly different as all were coloured by hand by one of John Cary’s professional (and non-geological) colourists. The first few copies of the Map were unsigned but following complaints by Smith about the varying quality, he began to inspect, sign and number each one.
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