The 1821 (second) edition of William Smith's geological map of Berkshire, one in a series of county maps produced by Smith, each separately issued, which were the first detailed geological maps of specific areas. Smith's individual maps are extremely rare on the market.

Smith produced the first geological map of England and Wales in 1815, which contained "an amazing amount of correct detail" (D.S.B.) and was the basis for all the geological maps that followed. In 1819 he began the publication of a geological atlas of England and Wales. Published in parts over five years, it remained unfinished, containing twenty-one maps of various English counties.

"All the county maps published contain much more information than was shown on Smith's large map of 1815, and indicate that during the intervening years he had done much to increase his knowledge. The maps are based on Cary's county maps, and are headed 'By W. Smith, Mineral Surveyor.' Each map measures 21 ½ inches by 19 1/4 inches [across the ruled border]; the scale varies slightly but averages 3 miles to an inch."–Sheppard, William Smith: His Maps and his Memoirs (1920), p. 155.

In his major work 'A Delineation of the Strata of England and Wales with part of Scotland' of 1815, Smith ordered the strata through a colour key, whereas here he identifies them by name and number with coloured boxes, and places them around the boundary adjacent to their outcrop.

Smith's map of Berkshire was first published by Cary in 1819, in part II of 'A New Geological Atlas of England and Wales', alongside Gloucester, Surrey, and Suffolk. It is a reissue of Cary's map of 1801, with the addition of the geological information.

There would appear to be no state changes to the plate between the 1819 and 1821. Though the red colouring, sometimes found on the 1819 edition, to the north edge of the 'Coral Rag & Pisolite', has been omitted on the present example. The box for 'Green Sand at & near Wantage' is uncoloured. We are aware of 1819 editions were the box is coloured and others where it remains blank.

The item also contains a printed letter from Joan Eyles to the owner of the map Dr Kerney, dated 24th May 1969. Joan Eyles was the leading authority on Smith's work, and her, 1969, paper 'William Smith: A Bibliography of his Published Writings, Maps and Geological Sections', remains a seminal work to this day. In the letter Eyles speculates about uncoloured box for 'Green Sand at & near Wantage', and goes on to plug her paper on William Smith's works.

Stratigraphy

Sand and Gravel. The highest Stratum in the County/ Sand, Gravel and Brickearth, over the Chalk, as at Speenhill.
Plastic Clay Sand and Gravel, over the Chalk
5 Chalk/ Lower Chalk, Firestone, &c above the Green  Sand  / Chalk, underpart / Chalk, upper part with Flints / Chalk, rising Southward abruptly to the high Ground of Inkpen Beacon 1011 feet above the Level of the Sea ___ The highest Ground in the Eastern and Southern parts of England.
6 Green Sand at & near Wantage
8 10 Sand of the Portland Rock
11 Oaktree Clay
12 Coral Rag & Pisolite / Coral Rag and Pisolite, found beneath the Clay in a late experiment for Coal.
13 Sand and Stone, beneath the Coral Rag at Kennington. / Sand and Sandstone
14 Clunch Clay & Shale ___The deepest Stratum in the County