Ancient Maps

Geological Mapping: Ireland’s 19thC Field Geologists

Maps are a form of illustration and illustrations often communicate a message more effectively than words. Geology is quite a difficult science for non-enthusiasts to acquaint themselves with. It follows then that geology lends itself particularly well to the use of maps to illustrate complex geological concepts. But where did geological maps come from originally? What kinds of people researched them and how did they do it? This article will attempt to answer these questions by discussing the history of Irish geological mapping with a particular emphasis on the people that carried out the mapping.


- The historical context

As far back as 1786 saw one of the first public calls for a geological map of Ireland, the rationale being that it would assist in identifying mineral resources. The first geological maps produced in Ireland, and indeed predating a map produced by William Smith for England and Wales, generally considered to have been the ground-breaker for geological maps, date back to around 1800. The main problem with geological mapping around this time was the lack of a base map (ordnance survey map) on which to record observations. A base map would allow the field geologist to note and align the position of rock outcrops to the detail already incorporated into it. In 1824 this problem was addressed with the establishment of the Ordnance Survey of Ireland (OSI). By 1846 the whole country had been mapped on a six-inch to one-mile scale (six inches on the map to one mile on the ground – 1:10,650).

In map terms the six-inch to one-mile scale is lavish, and, when in 1845 the Geological Survey of Ireland (GSI) was formed, geological mapping at this scale was venturing into the unknown in world terms. It turned out to be perfect for the task since the breadth of topographical detail meant that rock outcrops were virtually unmissable. Also the sheets themselves were big enough to record vast amounts of geological details. GSI’s brief was to map the entire country and the process that started that year in Co. Wexford was finished 42 years later in Co. Donegal. In the meantime it had been decided that publishing six-inch geological sheets for the whole country was too mammoth a task to complete. So from the 1850’s onwards whilst the fieldwork was done on the six-inch sheets the work was actually published at the newer OS one inch scale. The resulting one-inch series (1:63,360) numbered 205 sheets (together with accompanying descriptive memoirs) providing full coverage of the whole island. By 1890 the one-inch geological map of Ireland was finally complete and public.


was the mapping done?

During the 42 years of this field-mapping programme the field geologist (always male) was despatched to an area with two copies of the six-inch and two of the one-inch (OS sheets). One of the six-inch sheets was a working sheet onto which all exposures of rock had to be marked in pencil during the day’s fieldwork. In the evening his job included the tracing of all notes and illustration in Indian ink on a fair copy. Also he had to find time during evenings or wet days to duplicate his work on the second sheet. He then had to transfer his work to each of the two one-inch sheets that provided him with a broader context. When a one-inch sheet was complete it had to be sent off to HQ in London for approval, Then followed a series of returns until all required details were included and all parties were happy, before it went to the colourists in England for publication. All of the water-colouring of the maps (individually hand-painted) was done in England to maintain consistency of every sheet.

were the conditions like?

It is important for us to consider the type of lifestyle these 19th C field geologists must have had. Surely it must have been a lonely existence to be away from home for long periods of time? Indeed where was home? What must the wives and families have thought of their work and did they have to follow to the area of fieldwork?

We can’t paint a vivid picture of their lives without some degree of guesswork. Yet there are some interesting insights in records of the day. We can discern for instance that the men were educated and often from Britain. It seems certain that some of them felt that the people amongst whom they had to move and live were peasants and far beneath them. One of the first written descriptions of life as a GSI field geologist comes in 1845 from a gent named Smyth. In a letter to a superior he wrote about two of his colleagues – a “Welsh Squire” who was “in misery in Ireland” and “the captain who sports a ferocious pair of egg-brown moustaches.”

From the records we know that for the most part the men travelled on foot during the course of their day and rented lodgings nearby by night. In 1847 Wicklow was the main area of interest but parts of the county proved to be quite remote. One of the officers involved in the survey there was Willson who, it seems, was unable to find lodgings for the area around Kings River and Table Mountain. Thus, he sought and was granted permission to hire a horse and cart by day to get him to these areas in a timely fashion. However, a later record from 1856 indicates a low budget for such incrementals “and always the staff were wasting long hours tramping between their lodgings and their ground because there was never available sufficient money to allow for the regular hire of cars and horses.”

The records also reveal some interesting implications of the weather, the seasons and other natural conditions on the mapping programme. In 1847 we find mention of the famine which was obviously creating problems when in March officers were given a day’s leave in recognition of the great tragedy unfolding. Bad weather in 1852 rendered impossible surveying for two full months. In 1854 there are reports of officers meeting delays with “extensive spreads of peat and impenetrable thickets of furze.” In 1856 another bad summer was recorded having particularly adverse effects on mapping. In 1887 the final county to be mapped, Donegal, was completed. The last bit was around Ramelton and it was delayed until after the harvest because it was easier to access parts of the area then.

Woodblock scan

were the Field Geologists?

Many of the field geologists were studious in all aspects of natural history and produced engaging and important books, articles and studies of all kinds of topics including archaeology, bats, fish, botany, meteorology and zoology. Many of them were also accomplished artists. Many of these original sheets are decorated with all kinds of illustrations, some relevant i.e. a sketch of the landscape, some totally irrelevant e.g. a fair day scene or a dog chasing a hare! Oftentimes they would artistically record their drawings and illustrations on woodblocks. With woodblocks illustrations were drawn in reverse – imagine how difficult that must have been! – so that it would transport to the paper in its proper manner. Once drawn they would be “engraved” sometimes by the artist, then ink is rolled over the woodblock surface and finally pressure is applied to the block onto paper leaving an image. Woodblocks were the main means of printing illustrations for the memoirs written by the men as a description of the maps being produced. Woodblocks would later be superceded by photography.

Alongside these many diverse gifts often the field geologists managed to find time to indulge other passions such as fishing and shooting. Indeed on occasion, complaints were relayed to superiors by gamekeepers about members of the mapping team. One of the mappers, a man named Wilkinson, in his autobiography tells us that his most noteworthy day’s shooting resulted in 125 successful shots at game and fowl in the bogs of Co. Mayo! A further successful day for him, this time with a rod instead of a gun, resulted in him landing 102 salmon and grilse in and around Lough Melvin in Leitrim and Fermanagh!



Perhaps the most amazing thing about these men is that the maps they produced in the second half of the nineteenth century are still in almost constant use today in the offices of the GSI. Their value is undiminished with the passing of years, decades, indeed centuries, particularly now with the arrival of advanced scanning and digital technologies to extend their life-cycle even further. Unlike us, mere humans, the maps have a virtually infinite life-cycle, yet it was precisely the excellence of the original human effort which has made them so valuable, back then, today and far into the future. Hoorah for the original field geologists!

Written by Enda Gallagher, GSI, for Science Spin Issue 22. Research and Quotes from “North from the Hook” G. Herries Davies, GSI, 1995, and “Illustrating Irish Geology” Exhibition 2000, Matthew Parkes, Petra Coffey, Elaine Roche, Cartography Section GSI.