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History of the Geological Survey of Ireland first series of 1:63 360 maps

Early geological mapping in Ireland had its origins in the search for economic minerals. By the 1830s two geological surveys had been established, one being run from the Valuation Office by Sir Richard Griffith and the other run as part of the Ordnance Survey. In 1845 Sir Henry Thomas De La Beche became the founder and first Director of the civilian Geological Survey of the United Kingdom under the aegis of the First Commissioner of Her Majesty's Woods, Forests, Land Revenues, Works and Buildings. The Act of Parliament of 1845 establishing the Survey referred to the completion of a geological survey of Great Britain and Ireland. There was no specific reference to maps, but the implication to provide the results of the survey in map form was clearly there.

GSI field sheet showing the Stradbally area of Co. Waterford 6 inch sheet No. 32
GSI field sheet showing the Stradbally area of Co. Waterford 6 inch sheet No. 32

The first Local Director of the Geological Survey of Ireland was Sir Henry James. The Survey's appointed task under his leadership was to conduct a nationwide survey of Ireland and to produce a map significantly improving the 1839 Quarter-inch geological map of Ireland produced by Sir Richard Griffith. How the Survey was to proceed was laid down in the document issued by Henry De La Beche and dated 22nd. May 1845 and entitled: Instructions for Local Directors of the Geological Survey of Great Britain and Ireland. The mapping was to be conducted on the scale of six inches to the mile using the Ordnance Survey topographic maps at this scale as a base, which incidentally proved ideal for geological mapping, base maps at this scale are still used today. The final maps for the public were to be produced at a scale of one inch to one mile, 1:63 360. On 22 May 1845 De La Beche wrote to James instructing him to start the new Survey's mapping campaign in southeast Ireland, Dublin, Wicklow, Kilkenny, Carlow, Wexford and Waterford. There were two reasons for selecting this area. Firstly De La Beche had a team working just across St. George's Channel in Wales, working both sides could resolve common problems; and secondly, there were known economic deposits in the area, coal at Castlecomer and copper at Avoca, and it would have been foremost in De La Beche's mind to show the economic benefits of the new geological survey.

The start of one-inch geological map production was dependent on the availability of the Ordnance Survey 1:63 360 topographic sheets which were used as a base. This latter series was first authorised in April 1851 and it was intended to cover the whole country in fifty-nine sheets of the same dimensions as the Ordnance' Survey's six-inch maps, 90x60 cm. This size was thought to be too impractical so they soon decided to issue sheets a quarter of the size. Each sheet was numbered to the original 59 sheet series numbers with an additional quarter sheet designation, SW, SE, NW, NE for example 46 SE. This numbering system lasted until 1858 when it was proposed that the quarter sheets should be accorded full sheet status and would be numbered 1 to 205. Before 1873 the base OS maps used by the Geological Survey were the outline edition, from 1873 the 'hill edition' with hachuring was used.

Basalt weathering into spheroids. Hill area, Giant's Causeway, Co. Antrim
Basalt weathering into spheroids. Hill area, Giant's Causeway, Co. Antrim
From Du Noyer images available from the GSI website

Mapping proceeded in the field on six-inch sheets quartered for convenience of handling. The geologist recorded in pencil the rock types at each exposure and made notes or sketches in field notebooks. The information recorded would then be inked in during the evening. Another evening job was to duplicate the information on a second set of sheets, periodically the geologist would also draw the essentials onto a set of two one-inch maps. Each one-inch map would be sent to Dublin for approval on completion. When approval had been granted, the geologist would be given a new clean copy of the one-inch map onto which he placed all the information required for the published sheet. This was then sent to the Ordnance Survey for engraving - a first proof being returned. Final amendments were made and the first proof returned to the OS. After the amendments had been engraved the second proof came back and the geologist added the standard colours to make the 'pattern copy'. The pattern copy was the standard to which copies were coloured for sale, this was usually done by the Survey colourists in England.

In 1887 the primary geological survey of Ireland, begun over forty years earlier in 1845, was coming to a close. The summer of 1887 saw George Henry Kinahan and Sidney Berdoe Neal Wilkinson at work in far off Donegal. Wilkinson completed his work first and Kinahan stayed on until October, so finishing the survey. Gordon Herries Davies in his book "Sheets of many colours" tells the story:

"It must have been one evening towards the close of that month when Kinahan plied his hammer to the very last rock exposure to be examined during the primary geological survey of Ireland. Having peered at the resultant sliver of rock through his lens, he must have entered some comment in his notebook, recorded the site upon his field-sheet, closed his map-case, and turned his steps homeward. It was all a routine that he knew so well; thousands of other days in the field had ended for him in precisely the same way as the evening shadows lengthened. But this evening was really different. The geological campaign which had opened in County Wexford in the summer of 1845 was now at long last concluded. And how appropriate that it should have been Kinahan who made those final observations which brought the primary survey of Ireland to its close. He was a stormy character certainly, but in terms of service within Ireland he was the Survey's senior officer. For well over thirty years he had carried his hammer and his maps through some of Ireland's most rugged terrain; he surely deserved to strike the final hammer blow on behalf of the Survey. As he trudged home that last evening did his memories perhaps return to that now distant occasion in August 1854 when, fresh out of Trinity College, he had reported for training at Bantry, there to find himself in the inspiring company of Jukes, Ramsay, and Sir Henry De La Beche himself. In those days a one-inch geological map of Ireland was still merely a project under discussion, but now in Donegal he and Wilkinson had just fashioned those final pieces necessary to complete the great one-inch geological mosaic."

This was the close of the mapping programme. Production of the final maps took a few years longer, with the final seven maps published in 1890.

Limestone folding, Kanturk, Co. Cork

Limestone folding, Kanturk, Co. Cork
From Du Noyer images available from the GSI website

Perhaps the last word should go Mrs E. Williams the person responsible for colouring the one inch geological maps. Her job was to turn them from an uncoloured outline to what could be regarded as a work of art. Again a quote from Gordon Herries Davies in his book "Sheets of many colours" tells the story:

"Mrs E. Williams of 4 Stratford Villas, Camden Square, Camden Town, London. During the closing decades of the nineteenth century she was employed to work at home colouring those maps of the Geological Survey of Great. Britain and Ireland which were destined for distribution to the public. As we contemplate one of the early copies of that colourful final Irish one-inch sheet - Sheet 10 - it is Mrs Williams's handiwork that excites our admiration. Toiling in the grimy air of Victorian London, close to the Metropolitan Cattle Market and hard by the Midland Railway's line out of St Pancras, hers was a landscape far removed from the Irish landscape of purple mountains, tranquil rivers, sandy eskers, brown peat-bogs, and storm-beaten cliffs - an Irish landscape which had become so familiar to generations of geologists as they painstakingly traced out those geological lines which Mrs Williams's brush now had to follow with such care and precision."


Bailey, E.B. Geological Survey of Great Britain. London : Murby, 1952.

Department of Agriculture and Technical Instruction for Ireland. List of Memoirs, Maps, Sections &c., published by the Geological Survey of Ireland to March 31st, 1906.

Flett, J.S. The first hundred years of the Geological Survey of Great Britain. London : HMSO, 1937.

Herries Davies, G.L. Sheets of many colours: the mapping of Ireland's rocks 1750-1890. Dublin : Royal Dublin Society, 1983.

Herries Davies, G.L. North from The Hook: 150 years of the Geological Survey of Ireland. Dublin : Geological Survey of Ireland, 1995.

McKenna, G. (Ed) Instructions for the Local Directors of the Geological Survey of Great Britain and Ireland by Henry De La Beche 22nd May 1845. Selected documents from the BGS Archives No. 1 [Unpublished manuscript].

Owenson, N. Gray, G. McIntosh, R.P. Geological Survey of Ireland, 1:63 360 maps and associated sections: report on the digitization programme. British Geological Survey Internal Report IR/08/034