Henry Thomas De la Beche, at 39 years of age, now saw himself set on a course that would lead ultimately to a ‘Geological Survey of Great Britain’ (GSM 1/68, 121).
Yet the future of the fledgling Survey was by no means assured, for the seeds of future trouble had already been sown several months earlier. Between 1834 and 1839 De la Beche became embroiled in a major scientific controversy that would have far-reaching repercussions.
In the late summer of 1834, while working on sheet 26 of the Devonshire survey (Figure 16), De la Beche collected some fossil plants in strata closely associated with culm, an inferior coal, near Bideford in north Devon.
He arranged for these to be identified by John Lindley, the foremost authority on palaeobotany, who pronounced them all to be of plant species well known in the Carboniferous Coal Measures.
This surprised De la Beche, who expected only a rough affinity, for in his view the immense thickness of otherwise poorly fossiliferous slaty mudstones and sandstones within which the coal seams occur could only belong to the so-called Transition
or Greywacke strata below the Old Red Sandstone, and thus well below the Carboniferous.
De la Beche arranged for a short notice of his findings to be read at a meeting of the Geological Society in December of that year (De la Beche 1834).
His contention that the plant remains came definitely from the Greywacke, and were thus pre-Carboniferous, caused heated debate.
In opposition to this, Roderick Murchison, whose view was supported by Charles Lyell, insisted that the fossil evidence established a clear correlation between the ‘Culm’ strata and the Coal Measures.
In accepting the value of ‘characteristic fossils’ as a means of determining the relative age of rock formations, Murchison was unconditionally advocating the precepts laid down by William Smith.
Yet Smith’s views were far from being widely accepted at that time.
The significance of this argument, which dragged on for several years, was not only of academic interest, but had important economic implications. Murchison was keen to demonstrate that land plants, the raw material of coal, did not exist before the Old Red Sandstone, and thus it was futile to search for coal deposits in rocks of Transition or Greywacke age.
De la Beche’s insistence on the existence of Greywacke plants undermined this argument. However, even Murchison was not prepared initially to regard the whole of the Culm succession as Carboniferous in age, and was convinced that De la Beche had somehow overlooked a major unconformity.
At the annual meeting of the British Association at Bristol in August 1836, Murchison, with Adam Sedgwick, put forward a fundamentally different interpretation of the structure and position of the Culm strata of Devonshire.
It was a severe blow to De la Beche’s integrity as a field observer.
Furthermore, some influential figures were present at the meeting, including Spring-Rice, the Chancellor of the Exchequer.
De la Beche now became concerned that this public criticism of his work might prejudice the future of the Survey.
In a letter to Sedgwick he expressed his fears that the government’s continuing patronage of science, and in particular of geology, was a sensitive point because ‘they have been so often jobbed, and infernally jobbed, under the old systems, that they are always afraid of being jobbed again’ (Rudwick 1985, 175).
He may have had John MacCulloch’s recently published Geological Map of Scotland in mind (Figure 6), a map whose compilation had cost the Treasury an exorbitant sum of money.
De la Beche’s depressed state of mind at this time is conveyed in a sketch that he sent to his daughter, Bessie (Figure 17).
In February 1837, following some further acrimony between De la Beche and Murchison, the latter began to put about that he considered De la Beche to be grossly incompetent as a government surveyor (Rudwick 1985, 202).
These accusations reached official ears, with the result that on 3 April Colby despatched a letter to De la Beche informing him that ‘extremely unpleasant but not tangible reports of the inaccuracy of your Geological Survey are in circulation’ (GSM 1/68, 198-9).
As things stood, the geological survey of Cornwall was due to be finished by the end of June 1837, and De la Beche had already submitted cost estimates and received approval from the Treasury for an extension of the survey into the South Wales coalfield ― curiously, the Treasury made no allusion to the unresolved question of the total expenditure and time that would be required to complete the geological survey of Great Britain, although the matter would resurface in 1839.
Colby now recommended that priority be given to the publication of a full report on the geology of Devon and Cornwall, De la Beche having so far delayed publishing anything on the former until he had completed his mapping of the latter.
In his reply to Colby, De la Beche could only complain that ‘I have personal enemies, and unfortunately it is equally clear that they are actively employed against me.
While I toil day after day without rest, endeavouring to do my duty to the public and to return zeal and the best use I can make of my abilities for the confidence reposed in me, they can, and it appears do, buzz their accusations about, not neglecting the quarters when they conceive they can do me the most mischief, so that do what I will I have no chance’ (GSM 1/68, 200-1).
His letter finished on an ominous note: ‘My feelings tell me I should resign, but I would prefer an inquiry’ (his threat of resignation was omitted from the Ordnance Survey letter book, probably at Colby’s request, but the original letter survives: NMW 84.20G.D.378).
Close allies advised De la Beche not to think of resigning, and he was soon urging his good friend Greenough to lobby in influential quarters on his behalf (Rudwick 1985, 203-4).
This potential threat to De la Beche’s livelihood quickly subsided, thanks in part to the efforts of Greenough.
Indeed, the episode had a beneficial outcome, since Colby now conceded that the memoir on Devon and Cornwall should be published by the government and not at De la Beche’s personal expense as originally proposed (GSM 1/68, 203).
De la Beche spent about a month in the autumn of 1837 re-examining parts of Devonshire in order to resolve some of the issues raised by the Devonian controversy (Figure 18). In December of that year he moved his base of operation to Swansea in the South Wales coalfield.
February 1839 saw the publication of the Survey’s much-awaited first memoir: Report on the Geology of Cornwall, Devon, and West Somerset, a substantial work of 648 pages with folding map, sections and plans (it was without a detailed index, this being issued separately in 1903).
A revised version of the eight sheets of the one-inch geological map of Devonshire appeared in the same year.
De la Beche had by this time conceded to the separation of the Culm from the remainder of the ‘Grauwacke’ (he employed the original German form of the word), but was still unprepared to accept a Carboniferous age, preferring instead to designate the Culm lithologically by the term ‘Carbonaceous Series.’
Despite De la Beche’s reservations (or stubbornness!) a Carboniferous age for the Culm became increasingly difficult to deny as more ‘characteristic’ fossils came to light towards the end of the 1830s.
In March 1839 Murchison resolved the difficulty of accommodating the great thickness of associated Greywacke, which he had wrongly assumed to be unconformable with the Culm, by correlating it with the Old Red Sandstone whose lithology and organic remains is otherwise quite dissimilar.
In a joint paper with Adam Sedgwick, Murchison grouped these two series into a newly erected Devonian System.
In the Welsh Borders it was clear that the Old Red Sandstone lay between the Carboniferous Limestone above it and the formations of Murchison’s recently erected Silurian System below.
But the similar age of the Devonshire Greywacke only became apparent because its fossils exhibited affinities that were intermediate in character between those of the Carboniferous and Silurian Systems.
Charles Lyell considered ‘the culm question’ to be one of the most important theoretical issues ever to be discussed at the Geological Society (Rudwick 1985, 195-6).
The resolution of the Devonian controversy proved to be of global geological significance. It firmly established the value of fossils as stratigraphic markers, founded on an acceptance of organic change over time, although the manner and mechanism of this change had yet to be explained in terms of Darwinian evolution — that particular controversy was still to come!
Immediately following the publication of his Report in early February 1839, De la Beche made an application to the Board of Ordnance for the appointment of Geological Assistants.
Since 1835 he had worked largely on his own, with some limited assistance from two geologically-minded Ordnance Surveyors (Henry McLauchlan and Henry Still).
The Geological Society’s generous recommendation of a contingency fund for the employment of assistants, made in its 1835 report, had never been fully acted upon.
The Board responded testily, and once again pressed De la Beche for an estimate of the total cost and time involved in completing the whole survey. In his reply, De la Beche attempted to explain the difficulty of making such an estimate, given the varied geological complexity and economic development of the different regions of the country.
Though exasperated at De la Beche’s unwillingness to provide the required information, the Board nevertheless felt compelled to accede to his request, though only after further prompting from Colby.
With respect to the annual allocation of funding, it was simply agreed ‘from year to year to take such a sum as may be deemed advisable’ ― and so it was left at that! (GSM 1/68, 282-98).
On 17 April 1839, David Hiram Williams was appointed as the first Geological Assistant, soon to be followed by others. From this moment onward, De la Beche had effectively secured the long term future of the Geological Survey.
De la Beche was knighted in 1842, and died while still in service in 1855.
Ironically, the person who succeeded him as Director-General of the Geological Survey was his old former adversary, Sir Roderick Impey Murchison, whose accession was to mark another impressive chapter in the Survey’s history.
This paper grew out of a lecture that I gave to the East Midlands Geological Society in November 2006.
First and foremost I would like to thank the staff at the Library of the British Geological Survey for effectively treating me as one of their own, and for giving me unlimited access to the Survey’s rare-book collection and archives.
Tom Sharpe of the Department of Geology, National Museum of Wales, is thanked for helpful comments and for allowing me to reproduce Figures 15 and 17.
Except where otherwise attributed, all figures have been scanned and edited by the author.
Bate, D G. 2010 Sir Henry Thomas De la Beche and the founding of the British Geological Survey. Mercian Geologist, 17 (3). 149–165.