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Highlands controversy of Northwest Scotland

January 01, 1970

The Highlands controversy was a scientific controversy which started between British geologists in the middle of the nineteenth century concerning the nature of the rock strata in the Northwest Highlands of Scotland. The debate became contentious, even acrimonious, because of some of the personalities involved and because it pitted professional geologists of the Geological Survey against academic and amateur geologists. An initial resolution was achieved by about 1886 but the great complexity and scientific importance of the discovery of the Moine Thrust Belt and the geological processes involved in its creation led to field work continuing for a further twenty years culminating in the 1907 publication by the Geological Survey of a book of fundamental geological significance: The Geological Structure of the North-West Highlands of Scotland.

Suilven, Northwest Highlands – Torridonian sandstone standing on a base of Lewisian gneiss

The acrimony was an important factor in the political decision to set up the Wharton Committee of 1899 to review the state-funded Geological Survey. The committee's report probably precipitated the retiral of Archibald Geikie, the Survey's director-general, who had been slow to accept the new geological paradigm. However, in retirement Geikie's status flourished as he went on to become president both of the Geological Society and the Royal Society and to receive the Order of Merit.

The northwest highlands region of Scotland is now known to be where part of the Iapetus Ocean closed with the collision of the continents of Laurentia and Baltica about 400 million years ago. The consequent Caledonian Orogeny produced intense folding and compression of rocks – at thrust faults older rock strata slid for miles over younger rocks and, at nappes, the sequences of rock strata became inverted and duplicated at overturned anticlines.

Background edit

Geological science in the mid nineteenth century edit

 Geologic time scaleMesozoicPermianCarboniferousDevonianSilurianOrdovicianCambrianPrecambrianPaleozoic
Derived from
(clickable image)

From around 1830 geologists were beginning to date rocks according to the embedded fossils.[1] The law of superposition whereby younger rocks lie above older ones was very well established and it was recognised that some layers may be missing because they had been eroded away. Folding and faulting of strata were recognised and in 1841 Arnold Escher von der Linth discovered that sometimes older rocks lay above younger ones. However his explanation involved such large horizontal movements of rock and folding on such a massive scale that he was afraid to publish his results because his theory would seem ridiculous. It was not until after his death that his pupil Albert Heim published the findings in 1878.[2][3][4] Thrust faulting, where there is a considerable horizontal movement of younger strata over older, had not yet been identified.[5]

Roderick Murchison's expedition to Wales in 1831 led to his identification of the Silurian period and he came to regard the Silurian geological system as being his own territory.[note 1][7][2] He went on to decide that Silurian rocks extended into parts of England and southern Scotland and this caused bitter arguments with his friend Adam Sedgwick who had previously identified the rocks as Cambrian − the intervening Ordovician period was yet to be characterised.[8] Murchison identified the Silurian on the basis of the types of fossils the rocks contained whereas earlier geologists had studied the type of rock.[9] The strength of Murchison's views became buttressed by his knighthood in 1846 and when he was appointed director-general of the Geological Survey in 1855 he decided to turn his researches to the little-known and even less understood Northwest Highlands of Scotland expecting to extend his Silurian domain up there.[10]

Northwest Highlands of Scotland edit

 
Lewisian gneiss at Assynt

The Northwest Highlands were, and still are, remote and difficult to access. Along a coastal strip some 200 kilometres (120 mi) long and 15–25 kilometres (10–15 mi) wide the terrain is austere with isolated mountains rising above barren lower ground where knolls of bare rock lie among lochans and peat bogs. This geological region runs from the Sleat peninsula of Skye northward through Kyle of Lochalsh, Ullapool and Assynt to Cape Wrath and Loch Eriboll.[11][12]

 
Quartzite summit over sandstone on Beinn Eighe, Torridon

For the geologist Assynt provides some of the best formations of rock and the finest scenery. The low-lying hummocky ground to the west is of hard metamorphic rock – Lewisian gneiss, the oldest rock in Britain. Above this basement are less-disturbed sandstones, quartzite and some Durness limestone.[note 2] No fossils are to be found in the sandstone; the quartzite contained "Pipe Rock" but at the time this was not recognised as containing fossils;[note 3] and the fossils in the limestone could not be unambiguously dated at the time.[14] Away to the east of the coastal strip are the strongly metamorphosed Moine rocks which in places lie above non-metamorphosed strata.[15]

 
Pipe rock from Assynt

For nineteenth-century geologists, this was a major puzzle because younger rocks are expected to lie above older ones and so non-metamorphosed should lie above metamorphosed – what were the ages of the rocks and why did they seem to be in the wrong order?[16] Why had seemingly upper and lower layers of quartzite apparently been discovered both above and below basement gneiss?[17]

Murchison and Nicol in the Northwest Highlands edit

 
Roderick Murchison, 1857
 
Murchison's Silurian concept of Loch Assynt and Quinag, 1872 but published as early as 1859

In 1827 Murchison had made a cursory survey of the area from the sea but in 1855, hearing news of the discovery of fossils in the limestone at Durness, he visited again with James Nicol, professor of geology at Aberdeen University.[note 4] The fossils were thought to be Devonian and the limestone was clearly more recent than the underlying sandstone. This was a problem because the sandstone, later to be called Torridonian sandstone, was thought to be equivalent to the Old Red Sandstone on the east coast of Scotland which certainly contained Devonian fossils.[19] Because of the conditions on the ground they were unable to conduct a thorough geological survey but Murchison considered there was an ascending series (becoming younger) of strata exposed on the surface as one moved west to east. He concluded that this exemplified the stratigraphic column of Britain. The strata must dip down from west to east, he thought, so at any particular elevation the rocks towards the east were younger than those to the west and so, he assumed, the schist and gneiss of the north of Scotland were Silurian sediments above a basement.[20]

 
James Nicol

James Nicol, professor of geology at Aberdeen University disagreed. Following a separate visit in 1856 he claimed that a geological fault ran right down along the northwest coast and that the seemingly younger rocks were in reality far older having been shifted upwards compared with those to the west.[note 5][2] A matter that was to become especially difficult was that Murchison considered that there were two quartzite layers of different age at two stratagraphic levels whereas Nicol claimed there was one layer but vertically displaced along the fault.[22] However both geologists had to gloss over the difficulty that the quartzite was greatly folded and in some places seemed to fold over itself.[23]

In 1859, following another tour of the highlands when he was accompanied by his second-in-command at the Geological Survey, Andrew Ramsay, Murchison addressed a British Association in Aberdeen where he explained what he considered was the essential simplicity of the geology of the north of Scotland. It seems his lecture was regarded as a triumph by the attendees and by The Times and the Scottish press.[24] John Phillips spoke of the high estimation in which Murchison was held as "master of the Silurian". Nicol, meanwhile, had been preoccupied organising the geology section of the meeting – his paper hardly got a mention in the press and seems to have received little support at the meeting.[25]

Murchison involves Geikie edit

 
Murchison and Geikie geologising in the Scottish Highlands, Prosper Mérimée, 1860

In 1860 Nicol returned to the Northwest Highlands to investigate further and Murchison, after hearing of Nicol's travels, made a quite separate journey taking along with him a junior but very ambitious member of the Survey, Archibald Geikie. Murchison confirmed in his own mind what he had already observed and Geikie, anxious to please, became a strong supporter of Murchison's views.[26] However, in his posthumous biography of Murchison he was to say of the expedition that Murchison "stuck to his leading principle, from which no amount of contradictory detail would make him swerve".[27]

When Nicol announced the results of his latest investigations to the Geological Society in December 1860 he refuted Murchison's findings and rejected the presence of Silurian sediments. He considered igneous rock was to be found along a "zone of complication" from Durness to Skye and faulting was responsible for the perplexing strata. He utterly rejected Murchison's idea that metamorphic rock could lie with no unconformity (with no intervening period of erosion) over unaltered sedimentary layers. There was no evidence that the highlands were of Silurian age.[28] Murchison was enraged and wrote to his protegé Archibald Geikie "we have a fight in which our reputation and veracity are at stake".[29] In February 1861 he and Geikie delivered their paper to the Geological Society and this and Nicol's papers were published in the same volume of the Quarterly Journal of the Geological Society.[30][31]

 
Murchison's 1865 revision of his 1861 map showing a very extensive Silurian area[32]

At that time the geological community in Britain had not formed a definite opinion on these matters but Murchison's view was the one that was to prevail at least for a time. Murchison held great prestige and Geikie was a persuasive writer and speaker who was well able to place the best possible gloss on Murchison's views, sometimes by writing favourable anonymous reviews of the two geologists' own publications.[33] For example, Geike wrote a seemingly independent review of his and Murchison's 1861 map.[34] So, the Murchison–Geikie view became orthodox.[33]

Nicol and Murchison never resolved their differences and Nicol, after making little progress persuading the geological community of his theory, ceased publishing on the matter after 1866 although he continued to make geological field studies in the north of Scotland throughout his career. He died in 1879.[35]

Geikie was appointed director of the Scottish Geological Survey in 1867 and, in 1871, the year of Murchison's death, he was appointed to the newly created chair of Murchison professor of geology at Edinburgh University, endowed by Murchison himself. He continued to promulgate Murchison's Silurian theories and carried the professional geological establishment with him.[36]

Rising dissent in the 1880s edit

 
Horizontal strata of Torridonian sandstone on Beinn Alligin

At this time the Geological Society's members were academic geologists and amateurs, some of them becoming very knowledgeable and well respected. There were often differences of approach and opinion between, on the one hand, members of the Society and, on the other, senior spokesmen and managers of the "professionals" employed in the Geological Survey who carried out most of the actual fieldwork. The Survey's directors considered themselves better informed than amateurs and academics (who they regarded also as amateurs). From around 1878 papers by members of the Society started to appear, sometimes supporting Nicol and at other times just drawing attention to the inconsistencies in both contemporary theories and the incompatibility of the various field observations.[37]

Murchison retired as director-general in 1867 to be succeeded by Andrew Ramsay.[38] In 1880 an anonymous letter to The Times was highly critical of the state-funded Survey remarking that it had been set up to be, and should be, a temporary organisation, that it was prolonging its own existence and that the surveyors, rather than being peripatetic, were settling down in particular regions, hence exacerbating the problem.[39] The matter was debated in both Commons and Lords leading to inquiries by the Science and Art Department. Ramsay, by now in poor health, was not well able to defend his organisation – he had suggested it would take 22 years to complete the Scottish survey.[note 6] This led to his retirement in 1882 and a reduction in the staff and scope of the Survey's work.[40]

Geikie made further field trips in 1880 and 1881 and, although he noted several, or many, anomalies, he stuck with the Murchison paradigm of Silurian simplicity.[41] In 1882 Wilfred Hudleston wrote of a ubiquitous but unidentified type of rock, which was then being called "Logan rock" and is now known to be Lewisian gneiss, saying "this monster will, in most places, have to be dealt with on the basis of a fold over of some of the lower beds".[42] From about 1880 the first Ordnance Survey maps of northwest Scotland started to be published and these eased the work of the geologists. A few six-inch-maps came first, followed shortly by a one-inch series with contour lines.[43]

 
Charles Callaway

In 1881 an amateur geologist Charles Callaway surveyed in detail the Durness and Inchnadamph regions and presented a paper to the Geological Society saying the overlying gneiss could not have been formed more recently than the unmetamorphosed limestone below it. His paper generated considerable interest but little agreement except to say that the geological structure of the region was not currently understood. Not deterred by a Geological Survey letter to Nature assuring that Murchison's interpretation would "never be invalidated", the following year Callaway ventured north again equipping him in 1883 to write, according to Oldroyd, "one of the most important documents pertaining to the Highlands controversy". Indeed, in 1882 there was almost a score of geologists busy in the Highlands, knowing something was there to be discovered but not knowing what it was.[44]

Callaway now proposed a particular stratigraphic sequence of rocks (in order of the time they were originally deposited) and compared this with the sequence of strata he observed in vertical sections taken along lines at different locations and in different directions. He found that he could generally work out that some sequences were the right way up and that others were inverted. Where a particular type of rock had seemed to be at more than one position in the stratigraphic column it now appeared it was one layer folded over on itself. For Loch Eriboll Callaway claimed that over-hastiness had led earlier geologists to misread the geological situation. Only Nicol had seen the real structure and, Callaway said, he was pleased "however humbly, to vindicate his reputation". At the meeting where Callaway presented his paper it was well received and no one from the Geological Survey rose to make any objections.[45][46]

Underlying the debate about geological thrusts and faults at this time was a developing world view of the earth's geology. It was theorised that, because the earth was cooling, it was shrinking and, therefore, wrinkling and this was the cause of mountain building. Faults formed at areas of weakness as the land collapsed into the shrinking interior. In particular, faults developed beside the rigid Lewisian gneiss at the coastal region of northwest Scotland.[47][48]

Lapworth's discoveries edit

 
Lapworth, about 1880

Southern Uplands edit

 
Graptolite fossils from Dob's Linn

From about 1869, Charles Lapworth, then a schoolteacher, had been quietly surveying the geology of the Southern Uplands of Scotland as a hobby. There are few fossils except in some dark shale bands which are packed with the fossils of graptolites. Previously geologists, if they considered graptolites at all, had considered them as an unreliable indicator of age whereas Lapworth identified different species at different levels. Because these free-floating creatures had turned to fossils in sedimentation on the sea bed this gave a good indication of the era in which each species had lived and died, regardless of the prior geological stratification of the ground on which they were deposited. Between about 1872 and 1877 Lapworth studied the locality known as Dob's Linn where an anticline makes it likely the five layers of dark shale have not been inverted in the immediate vicinity so, knowing the order of ages of rock, he could work out the order of ages of the different species.[49]

By applying this knowledge over the Southern Uplands as a whole he could tell that, after the fossils had been laid down, the land had often been severely folded sometimes to the extent of being overturned with a single geological layer being duplicated. This showed that the Geological Survey's maps of the area were in error in showing the rock to be Silurian and so the Survey was forced to map the area all over again using Lapworth's detailed techniques. In 1872 Lapworth had been elected as a fellow of the Geological Society – he went on to become a world authority on graptolites and was appointed professor of geology and metallurgy in 1881.[50]

Northwest Highlands edit

The Silurian theory received another setback when Lapworth examined the Northwest Highlands in 1882 and 1883.[50] In 1882 Lapworth had made an inch by inch inspection and discovered that the "upper" and "lower" quartz layers were in reality part of a single layer folded over on itself and by the following year he was able to demonstrate this convincingly to colleagues. At Durness and Eriboll where the layers of rock were most pronounced he could not find fossils sufficiently indicative for his purposes so he had to turn to lithostratigraphy rather than continue with the biostratigraphy he had used so successfully in the Southern Highlands. Detailed examination of the lithological characteristics enabled him to build up a finely divided geological sequence and place it in the correct stratigraphical order.[51] At Eriboll he recognised that it was foliation that could be observed, not sedimentary bedding planes, and the foliation was the result of large lateral forces from the southeast forcing older rocks to slide over younger ones.[52][53] What Murchison had identified as bedding planes – adjacent layers of different types and ages of rock – were actually thrust planes – dislocations in a layer caused by sideways thrusting having occurred.[50]

"For many years the Highland controversy has appeared to outsiders, and to those geologists who were unaware of the difficulties attending the stratigraphy of the older rocks, as a trivial dispute between the Geological Survey on the one hand and a few misguided amateurs on the other."

— Charles Lapworth, "On the Close of the Highland Controversy", Geological Magazine (1885)[54]

Peach and Horne edit

 
Horne (left) and Peach, 1912
 
Glencoul Thrust – Cambrian rock sandwiched between layers of older Lewisian

Geikie, who had been appointed director-general of the Geological Survey in 1882, arranged for his colleagues Ben Peach and John Horne to make a detailed survey of the Northwest Highlands starting in 1883 with the intention of confirming Murchison's hypothesis.[55][56] After only one season they were able to report that Lapworth had again been correct at least in the northern Durness-Eriboll region although Geikie still saw the evidence as favouring Murchison.[57][58] However, by the following year, after a more southerly survey, Geikie became convinced when he was shown Torridonian sandstone metamorphosed to schist and he wrote in support of the new theory in his preface to Peach and Horne's 1884 report where he made first use of the term "thrust plane".[59][60][61]

There had been no great differences of opinion between the officers of the Geological Survey out in the field and the amateur and academic geologists likewise engaged. Rather it was the successive directors of the Survey, Murchison, Ramsay and Geikie, who had been unwilling to accept that the official position was unsatisfactory. By 1884, with the stratigraphy less contentious, Geikie extended the remit of the survey to include the petrology of the metamorphic rocks – what they had been made from in the first place.[62][63] Recognising that his organisation was not strong in petrology or petrography compared with the work elsewhere in Europe, particularly Germany, in 1884 Geikie started approaching Jethro Teall to join the Survey and at last persuaded him in 1888, the year Teall's book British Petrography was published.[64][65][note 7] By the time of Peach and Horne's 1888 paper they were able to extend their analysis of the complex stratigraphy to many more locations along the fault and by 1891 all ideas of Silurian rocks in northwest Scotland had been abandoned.[67][68] So, confirming Lapworth's view, what Murchison had considered to be Silurian was now identified on the basis of the Durness fossils to be Cambrian and the Torridonian sandstone was placed in the later stages of the Precambrian.[69] A series of geological maps was produced in this period at scales of one inch and six inches to the mile.[70][note 8]

Wharton Committee edit

In a series of articles on "scientific worthies", in December 1892 Nature published an adulatory article about Geikie, written by his close friend and eminent French geologist Albert Auguste de Lapparent. Dealing with the Highlands Controversy, it said that Murchison's theory had never "quite satisfied" Geikie who, for his "love of truth", had delegated to Peach and Horne the task of making a new survey of the region without any preconceptions. No mention was made of any involvement by geologists outside the Geological Survey.[75][76][note 9] Soon after this an editorial article appeared in the Daily Chronicle condemning the state-funded system in England that allowed eminent establishment scientists to "blunder with impunity".[note 10] The article continued that Murchison's "absurd theory" had been strongly supported by Geikie who had then instituted a second survey of the whole region, both carried out at the taxpayers' expense. Letter writing extended onto The Times and broadened to discuss the whole British scientific establishment, particularly the Royal Society, with suggestions of corruption.[79]

Geologists regarded the work in northwest Scotland as being of considerable scientific importance but the Scottish work (which held little commercial significance) lagged far behind that in England, Wales and Ireland. Politicians, under pressure from both commercial and tax-saving lobbies, started questioning the work of the Geological Survey and there was a proposal to transfer it from the Department of Science and Art to the Ordnance Survey. In 1900 a committee under John Wharton started to inquire into these matters.[80] The committee found in favour of the Survey's continuance, recommended improved staff pay and working conditions, and a transfer to the Board of Education. There was no explicit criticism of Geikie but the committee's report was likely to have led to his retirement the next year.[81] Horne was interviewed by the committee and was promoted to become deputy director to Teall, taking responsibility for Scotland. Peach wrote an extremely generous letter on the occasion of Geikie's retirement which Geikie published in his 1924 autobiography.[82]

Geological Structure of the North-West Highlands of Scotland edit

 
Moine Thrust at Knockan Crag

Peach and Horne continued their work and published The Geological Structure of the North-West Highlands of Scotland in 1907 with Geikie, in his retirement, making the final editing.[83] Their research was into one of the most geologically complex regions of Britain,[note 11] and they introduced the term "Moine Thrust".[note 12][85] In his preface to the memoir, Geikie refers the area of the Moine Thrust as being a place to study "some of the more stupendous kinds of movement by which the crust of the earth has been affected".[86][note 13]

The introduction to the memoir, written by Horne, provides an accessible description of geological structure that had been uncovered. Horne describes four groups of rocks, dealing with them from oldest to youngest, west to east. First, along the west coast, the Lewisian complex of gneiss stretches from Cape Wrath to Loch Torridon and then out to the Hebridean islands South Rona and Raasay. The topology is low, rounded and hollowed, only occasionally forming peaks such as at Ben Stack. The rock is ancient and highly metamorphosed of igneous and occasionally sedimentary origin, with many igneous dykes and sills intruding. Before this was overlaid by Torridonian sandstone it was subject to immense stress towards west-northwest deforming the intrusions and the heat generated produced further metamorphosis. There was then a long period of erosion of what was then a land surface before the much later Torridonian sandstone sedimentation.[88]

Secondly. the overlying Torridonian sandstones show gently inclined sedimentary strata with minor faults and joints that have eroded away to form the buttresses of high mountains. No definite fossils could be found. After a long period of marine erosion, the rock that was laid down on top, white over dark red, could be dated as Cambrian, indicating that the Torridonian sandstone was Precambrian. Where later earth movements thrust into and over the sandstone it became metamorphosed into schist.[89]

 
Peach and Horne's illustration of trilobite Olennus fossils from northwest Scotland[90]

Thirdly is a series of marine sedimentary layers – quartzite, dolomite and limestone – within which was discovered Cambrian age trace trilobite fossils. Peach and Horne remarked that the fauna are "identical" to those in the corresponding geological strata in North America.[note 14] Occasionally the sedimentary rock rests on the basement gneiss when the Torridonian sandstone had been completely eroded away, such as just south of Loch Assynt. These layers are separated from the underlying sandstone by an unconformity during which time interval the sandstone was folded and greatly eroded away, sometimes completely. The Cambrian sediment became intersected with sills and dykes, particularly near Inchnadamph.[93]

Fourthly, and what became the most interesting feature for the geologists, was the immense horizontal movement of rock over all these layers that occurred subsequently towards the west-northwest.[note 15] The underlying rock became broken up into slices that became piled up (imbricated) between thrust planes that also became folded. Basement Lewisian gneiss could be thrust up to the surface and rock strata could be shifted around to the extent that they could become inverted in their sequence – for example gneiss could overlay limestone. The main thrust, the Moine Thrust, moved schist from the east towards and over the pre-existing rock on the west while the effect of shearing at the thrust itself was to metamorphose the material at the interface into a mylonite structure. In "pipe rock" the deformation had the effect of bending over fossilised vertical worm casts so they become flattened horizontally. At one time this material extended much further to the west but it, and the underlying rocks, have been eroded, so exposing the underlying rocks and their geological history.[95]

 
Geological cross section at Glencoul Thrust, extracted from Peach & Horne (1923)[note 16]

The work has been described as "one of the most notable geological memoirs ever published in the English language".[96] According to Butler, the memoir has provided a "startling synthesis" describing, for the first time, the folds within imbricate slices and thrust sheets and the thrusts that delimit them.[87] So definitive was the work that it was not until 1980 that the structural evolution of the region again started being reinvestigated including with deep seismic profiling techniques. Imbricate faulting was proposed to explain the asymmetrical pattern of the stratigraphy that could not be explained by folding. The 1907 memoir and its accompanying 1-inch (1:63360) geological maps have been inspiring to geologists and have given what was arguably the start of thrust belt research worldwide and showed the importance of field mapping for tectonic research.[87]

Afterwards edit

 
Hebridean Terrane
 
Moine Supergroup and Moine Thrust Belt

The region of the Moine Thrust is now known to be where part of the Iapetus Ocean closed with the collision of the continents of Laurentia and Baltica about 400 million years ago. The consequent Caledonian Orogeny produced intense folding and rocks of what is now called the Moine Supergroup were thrust a distance of some 100 km (60 miles) over the strata at the northwest coast.[note 17][98][99] There is a particularly good exposure of the strata at Knockan Crag, now the site of the Knockan Crag National Nature Reserve, within the North West Highlands Geopark.[100]

 
Peach and Horne memorial, 1930
 
Peach and Horne statue, 2001

On the centenary of the publication of The Geological Structure, the Geological Society published an article by Rob Butler discussing the book's continuing significance.[87] Butler says the memoir was considered to be "an instant classic" and a "masterpiece of regional geoscience" leading to generations of geology students visiting the area, now marked by a memorial, to learn about "the golden years of NW Highland geology".[87][note 18] Much of the discussion of the geology of the Lewisian complex in the memoir is now taken for granted and it correctly identified the deformation of the intruding dykes and sills and the association between deformation and metamorphism.[102]

As well as the 1930 memorial at Inchnadamph, a statue of the two geologists was erected at Knockan Crag in 2001.[103]

See also edit

Notes edit

  1. ^ His sometimes sceptical colleagues sometimes referred to Murchison as the "King of Siluria".[6]
  2. ^ The sandstone and quartzite have been hugely eroded until all that is left are the stumpy mountains such as Canisp and Suilven.
  3. ^ "Pipe Rock" is quartzite containing the traces of burrows of skolithos marine worms.[13]
  4. ^ The fossils had been discovered by Charles Peach an amateur naturalist and fossil hunter who sometimes accompanied Murchison on field trips. He was the father of Ben Peach.[18]
  5. ^ Nicol supposed a somewhat vertical fault.[21] Highly inclined thrust faults were yet to be discovered (by Peach and Horne).
  6. ^ Ramsay estimated 21/2 years for England and Wales and 71/2 years for Ireland to complete the surveys.
  7. ^ In 1883 Thomas George Bonney had very publicly criticised the lack of knowledge of petrology shown by Geikie personally and by the Survey of which he had so recently become director-general.[66]
  8. ^ For example Peach and Horne's survey of Durness and Eriboll, published 1889, is on map 114[71] and a 1923 composite of the 1892 maps of Assynt was published in 1923.[72] The Assynt map was reprinted in 1947 and, with minor emendations, in 1965.[73] Since that time it has been fully revised.[74]
  9. ^ Geikie responded to this, in part, "I was finally convinced that they were untenable by the brilliant mapping of my colleagues, Messrs. Peach and Horne, who, following Prof. Lapworth's lead, share with him in the glory of one of the greatest achievements of field geology in recent times.".[77]
  10. ^ The editorial named Huxley, Hooker and Geikie.[78]
  11. ^ Britain is itself geologically complex by world standards.
  12. ^ Peach and Horne wrote "Ever since the time of Macculloch, at the beginning of last century, the stratigraphical position and relative age of these rocks have been a subject of animated discussion and, for a time, of keen controversy. Relying on the apparent order of superposition, the earlier observers naturally inferred from the magnificent sections laid bare along the western fjords and on the grand escarpments and dip-slopes of the mountains that the Eastern Schists follow the Cambrian strata in conformable sequence. But the geological structure which seems at first sight so simple, has proved, on later detailed examination, to be extremely complicated. The apparent succession has been found to be deceptive, and the superposition, which is undeniable, is now ascertained to be due to great terrestrial displacements, which have no parallel elsewhere in Britain."[84]
  13. ^ Much of the theory of thrust belts derived from the work in Peach and Horne's 1888 paper.[87][67]
  14. ^ Peach and Horne acknowledged Salter as having pointed out in 1859 that the Durness limestone fossils show greater similarity with those in America rather than Europe.[91][92]
  15. ^ The overthrusting was caused by the collision of the continents Laurentia and Baltica, generating the Caledonian orogeny.[94]
  16. ^ A key to the symbols and colouring of the map is at File:Glencoul Thrust, 1923, key landscape.png. The entire map is available online.[72]
  17. ^ What Murchison had called the Eastern schists or Moine schists (or gneiss because at first schist and gneiss were not clearly distinguished) was later termed the Moine Supergroup.[97]
  18. ^ In his monumental work of 1909, The Face of the Eart, Eduard Suess wrote "the Geological Survey has issued such a masterly report by Peach and Horne and their colleagues that it may almost be said to make the mountains transparent".[101][87]

References edit

Citations edit

  1. ^ Oldroyd (1990), pp. 4, 29–32.
  2. ^ a b c Gillen (2003), p. 69.
  3. ^ Dryburgh, Ross & Thompson (2014), pp. 2, 12.
  4. ^ Oldroyd (1990), pp. 135–136.
  5. ^ Oldroyd (1990), p. 60, 82–83.
  6. ^ Oldroyd (1990), p. 31.
  7. ^ Oldroyd (1990), pp. 29–31.
  8. ^ Oldroyd (1990), pp. 4–5.
  9. ^ Oldroyd (1990), p. 30.
  10. ^ Oldroyd (1990), pp. 49–50.
  11. ^ Oldroyd (1990), pp. 20–24.
  12. ^ Dryburgh, Ross & Thompson (2014), p. 1.
  13. ^ Butler, Rob. "Stratigraphic Notes". The Moine Thrust Belt. Leeds University. from the original on 10 March 2017. Retrieved 3 November 2017.
  14. ^ Oldroyd (1990), pp. 33, 36.
  15. ^ Dryburgh, Ross & Thompson (2014), p. 4.
  16. ^ Dryburgh, Ross & Thompson (2014), pp. 12–14.
  17. ^ Oldroyd (1990), p. 37.
  18. ^ Oldroyd (1990), pp. 48–49, 268.
  19. ^ Oldroyd (1990), p. 32, 48–51.
  20. ^ Oldroyd (1990), pp. 50–51, 64.
  21. ^ Oldroyd (1990), pp. 57–59.
  22. ^ Oldroyd (1990), pp. 5, 68.
  23. ^ Oldroyd (1990), pp. 80–81.
  24. ^ Oldroyd (1990), pp. 74–87.
  25. ^ Oldroyd (1990), pp. 88–89.
  26. ^ Oldroyd (1990), pp. 93–121.
  27. ^ Geikie (1875), p. 238.
  28. ^ Oldroyd (1990), pp. 122–137.
  29. ^ Oldroyd (1990), pp. 139–143.
  30. ^ Nicol (1861), pp. 85–113.
  31. ^ Murchison & Geikie (1861), pp. 171–240.
  32. ^ Murchison, Geikie & Johnston (1865), p. 31.
  33. ^ a b Oldroyd (1990), pp. 139–149.
  34. ^ Anon (Geikie) (1861), pp. 125–156.
  35. ^ Oldroyd (1990), pp. 43, 148–149.
  36. ^ Oldroyd (1990), pp. 5, 156–157, 167–168.
  37. ^ Oldroyd (1990), pp. 67–68, 173–188.
  38. ^ Oldroyd (1990), p. 75.
  39. ^ Observer (22 June 1880). "The Geological Survey". The Times. p. 10. from the original on 20 January 2022. Retrieved 20 January 2022.
  40. ^ Oldroyd (1990), pp. 75, 267.
  41. ^ Oldroyd (1990), pp. 188–192.
  42. ^ Oldroyd (1990), pp. 202, 379.
  43. ^ White (2010), pp. 505, 510.
  44. ^ Oldroyd (1990), pp. 202–207.
  45. ^ Oldroyd (1990), pp. 207–213.
  46. ^ Callaway (1883), pp. 355–422.
  47. ^ White (2010), pp. 513–514.
  48. ^ see, for example, Geikie (1903), pp. 394–397
  49. ^ Oldroyd (1990), pp. 217–231.
  50. ^ a b c Oldroyd (1990), pp. 219–234.
  51. ^ Oldroyd (1990), pp. 242–244.
  52. ^ Oldroyd (1990), pp. 219–234, 246–247.
  53. ^ Lapworth, Charles (1883). "The Secret of the Highlands - Part 1". Geological Magazine. 10: 120–128. doi:10.1017/S0016756800164313. S2CID 248533747.
    Lapworth, Charles (1883). "The Secret of the Highlands - Part 2". Geological Magazine. 10: 193–199. doi:10.1017/S0016756800166191. S2CID 126649782.
    Lapworth, Charles (1883). "The Secret of the Highlands - Part 3". Geological Magazine. 10: 337–344. doi:10.1017/S0016756800166671. S2CID 197532557.
  54. ^ Lapworth (1885a).
  55. ^ Oldroyd (1990), p. 254.
  56. ^ White (2010), p. 510.
  57. ^ Peach & Horne (1884), pp. 31–35.
  58. ^ Oldroyd (1990), p. 275.
  59. ^ Geikie (1884), pp. 29–31.
  60. ^ Oldroyd (1990), p. 278.
  61. ^ Oldroyd (1996), pp. 146–148.
  62. ^ Oldroyd (1990), pp. 258–259, 276.
  63. ^ Lapworth (1885b), pp. 1025–1027.
  64. ^ Oldroyd (1990), pp. 252–253, 263.
  65. ^ Teall (1888).
  66. ^ Oldroyd (1996), p. 145.
  67. ^ a b Peach & Horne (1888), pp. 378–441.
  68. ^ Oldroyd (1990), pp. 286, 293, 314.
  69. ^ Oldroyd & Hamilton (2002), p. 36.
  70. ^ "Geological Survey, One-Inch to the Mile - 1850s-1940s - National Library of Scotland". National Library of Scotland, maps. Geological Survey, Ordnance Survey. from the original on 28 January 2022. Retrieved 28 January 2022.
    "Geological Survey, Six-Inch to the Mile - 1850s-1940s - National Library of Scotland". National Library of Scotland, maps. Geological Survey, Ordnance Survey. from the original on 28 January 2022. Retrieved 28 January 2022.
  71. ^ "Sheet 114 – Tongue. Solid and drift edition". National Library of Scotland, maps. Geological Survey, Ordnance Survey. 1889. from the original on 28 January 2022. Retrieved 28 January 2022.
  72. ^ a b "Parts of sheets 107. 108, 101, 102 – Assynt district". National Library of Scotland, maps. Geological Survey, Ordnance Survey. 1892–1923. from the original on 28 January 2022. Retrieved 28 January 2022.
  73. ^ Oldroyd (1990), p. 283.
  74. ^ Assynt (B) Special Sheet [Folded Map]. British Geological Survey. 2007. ISBN 9780751835120. from the original on 3 February 2022. Retrieved 3 February 2022.
  75. ^ de Lapparent (1893), pp. 217–220.
  76. ^ Hamilton (1991), pp. 63–64.
  77. ^ Geikie (1893), pp. 292–293.
  78. ^ Hamilton (1991), p. 68.
  79. ^ Hamilton (1991), pp. 68–73.
  80. ^ Oldroyd (1996), pp. 307–321.
  81. ^ Oldroyd (1996), pp. 323–324.
  82. ^ Oldroyd (1996), pp. 326–328.
  83. ^ Oldroyd (1996), p. 271
    Peach & Horne (1907)
  84. ^ Peach & Horne (1907), p. 1.
  85. ^ Peach & Horne (1907), pp. 8, 466–471
    Oldroyd (1990), p. 281
  86. ^ Butler (2007)
    Peach & Horne (1907), p. vi
  87. ^ a b c d e f Butler (2007).
  88. ^ Peach & Horne (1907), pp. 1–4.
  89. ^ Peach & Horne (1907), pp. 4–6.
  90. ^ Peach & Horne (1892), pp. 240–241.
  91. ^ Peach & Horne (1907), p. 376.
  92. ^ Dalziel (2010), p. 189.
  93. ^ Peach & Horne (1907), pp. 5–7, 375–376.
  94. ^ Johnstone & Mykura (1989), pp. 10–11.
  95. ^ Peach & Horne (1907), pp. 7–10.
  96. ^ Dryburgh, Ross & Thompson (2014), p. 15.
  97. ^ Strachan & Holdsworth (2010), p. 233.
  98. ^ Ross (1991), pp. 26–28.
  99. ^ Johnstone & Mykura (1989), pp. 9–11, 49–55.
  100. ^ Breckenridge, Jan (2007). "The Story of Knockan Crag National Nature Reserve" (PDF). Scotland's National Nature Reserves. (PDF) from the original on 25 May 2021. Retrieved 12 March 2022.
  101. ^ Suess (1909), p. 529.
  102. ^ Butler (2007)
    Law & Butler (2010), pp. 1–5
  103. ^ "Monument to Geologists Ben Peach (1842–1926) and John Horne (1848–1928) | Art UK". Discover Artworks. Art UK. 2013. from the original on 12 March 2022. Retrieved 12 March 2022.

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  • Peach, Benjamin; Horne, John; Gunn, William; Clough, Charles; Hinxman, Lionel; Teall, Jethro (1907). Geikie, Archibald (ed.). The Geological Structure of the North-west Highlands of Scotland. H.M. Stationery Office. (alternative source at Internet Archive).
  • Peach, B.N.; Horne, J.; Clough, C.T.; Hinxman, L.W.; Cadell, H.M.; Dinham, C.H. (1923). "BGS Assynt Special Sheet". www.largeimages.bgs.ac.uk. British Geological Survey, copyright NERC.. This map is linked to from Gateway to the Earth. "Record details Assynt district". www.bgs.ac.uk. British Geological Survey. Retrieved 5 November 2017.
  • Ross, S (1991). "The Geology of Sutherland". In Omand, Donald (ed.). The Sutherland Book. Golspie: Northern Times. ISBN 1-873610-00-9.
  • Strachan, R. A.; Holdsworth, R. E.; Krabbendam, M.; Alsop, G. I. (2010). "The Moine Supergroup of NW Scotland: insights into the analysis of polyorogenic supracrustal sequences". Geological Society, London, Special Publications. 335 (1): 233–254. Bibcode:2010GSLSP.335..233S. doi:10.1144/SP335.11. S2CID 129225043.
  • Suess, Eduard (1909). "Part V, The Face of the Earth (continued)". The Face Of The Earth Vol. 4. Translated by Sollas, Hertha B.C.; Sollas, Hertha W.J. p. 529.
  • Teall, J. J. H. (1888). British petrography: with special reference to the igneous rocks. London: Dulau.
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Further reading edit

  • Bentley, Callan (19 April 2017). "Travels in Geology: Geo-diversity and geologic history in the North West Highlands of Scotland". Earth. American Geosciences Institute.
  • Butler, Robert W. H. (2010). "The Geological Structure of the North-West Highlands of Scotland – revisited: Peach et al. 100 years on". Geological Society, London, Special Publications. 335 (1): 7–27. Bibcode:2010GSLSP.335....7B. doi:10.1144/SP335.2. S2CID 129335860.
  • Murchison, Roderick Impey (1854). Siluria : a history of the oldest rocks containing organic remains (1 ed.). London: John Murray.
  • "The Highlands Controversy". North West Highlands Geopark. Retrieved 13 March 2022. and subsequent linked pages

January 01, 1970
highlands, controversy, northwest, scotland, highlands, controversy, scientific, controversy, which, started, between, british, geologists, middle, nineteenth, century, concerning, nature, rock, strata, northwest, highlands, scotland, debate, became, contentio. The Highlands controversy was a scientific controversy which started between British geologists in the middle of the nineteenth century concerning the nature of the rock strata in the Northwest Highlands of Scotland The debate became contentious even acrimonious because of some of the personalities involved and because it pitted professional geologists of the Geological Survey against academic and amateur geologists An initial resolution was achieved by about 1886 but the great complexity and scientific importance of the discovery of the Moine Thrust Belt and the geological processes involved in its creation led to field work continuing for a further twenty years culminating in the 1907 publication by the Geological Survey of a book of fundamental geological significance The Geological Structure of the North West Highlands of Scotland Suilven Northwest Highlands Torridonian sandstone standing on a base of Lewisian gneiss The acrimony was an important factor in the political decision to set up the Wharton Committee of 1899 to review the state funded Geological Survey The committee s report probably precipitated the retiral of Archibald Geikie the Survey s director general who had been slow to accept the new geological paradigm However in retirement Geikie s status flourished as he went on to become president both of the Geological Society and the Royal Society and to receive the Order of Merit The northwest highlands region of Scotland is now known to be where part of the Iapetus Ocean closed with the collision of the continents of Laurentia and Baltica about 400 million years ago The consequent Caledonian Orogeny produced intense folding and compression of rocks at thrust faults older rock strata slid for miles over younger rocks and at nappes the sequences of rock strata became inverted and duplicated at overturned anticlines Contents 1 Background 1 1 Geological science in the mid nineteenth century 1 2 Northwest Highlands of Scotland 2 Murchison and Nicol in the Northwest Highlands 3 Murchison involves Geikie 4 Rising dissent in the 1880s 5 Lapworth s discoveries 5 1 Southern Uplands 5 2 Northwest Highlands 6 Peach and Horne 7 Wharton Committee 8 Geological Structure of the North West Highlands of Scotland 9 Afterwards 10 See also 11 Notes 12 References 12 1 Citations 12 2 Works cited 12 3 Further readingBackground editGeological science in the mid nineteenth century edit nbsp Derived fromPage amp Lapworth 1883 clickable image From around 1830 geologists were beginning to date rocks according to the embedded fossils 1 The law of superposition whereby younger rocks lie above older ones was very well established and it was recognised that some layers may be missing because they had been eroded away Folding and faulting of strata were recognised and in 1841 Arnold Escher von der Linth discovered that sometimes older rocks lay above younger ones However his explanation involved such large horizontal movements of rock and folding on such a massive scale that he was afraid to publish his results because his theory would seem ridiculous It was not until after his death that his pupil Albert Heim published the findings in 1878 2 3 4 Thrust faulting where there is a considerable horizontal movement of younger strata over older had not yet been identified 5 Roderick Murchison s expedition to Wales in 1831 led to his identification of the Silurian period and he came to regard the Silurian geological system as being his own territory note 1 7 2 He went on to decide that Silurian rocks extended into parts of England and southern Scotland and this caused bitter arguments with his friend Adam Sedgwick who had previously identified the rocks as Cambrian the intervening Ordovician period was yet to be characterised 8 Murchison identified the Silurian on the basis of the types of fossils the rocks contained whereas earlier geologists had studied the type of rock 9 The strength of Murchison s views became buttressed by his knighthood in 1846 and when he was appointed director general of the Geological Survey in 1855 he decided to turn his researches to the little known and even less understood Northwest Highlands of Scotland expecting to extend his Silurian domain up there 10 Northwest Highlands of Scotland edit nbsp Lewisian gneiss at Assynt The Northwest Highlands were and still are remote and difficult to access Along a coastal strip some 200 kilometres 120 mi long and 15 25 kilometres 10 15 mi wide the terrain is austere with isolated mountains rising above barren lower ground where knolls of bare rock lie among lochans and peat bogs This geological region runs from the Sleat peninsula of Skye northward through Kyle of Lochalsh Ullapool and Assynt to Cape Wrath and Loch Eriboll 11 12 nbsp Quartzite summit over sandstone on Beinn Eighe Torridon For the geologist Assynt provides some of the best formations of rock and the finest scenery The low lying hummocky ground to the west is of hard metamorphic rock Lewisian gneiss the oldest rock in Britain Above this basement are less disturbed sandstones quartzite and some Durness limestone note 2 No fossils are to be found in the sandstone the quartzite contained Pipe Rock but at the time this was not recognised as containing fossils note 3 and the fossils in the limestone could not be unambiguously dated at the time 14 Away to the east of the coastal strip are the strongly metamorphosed Moine rocks which in places lie above non metamorphosed strata 15 nbsp Pipe rock from Assynt For nineteenth century geologists this was a major puzzle because younger rocks are expected to lie above older ones and so non metamorphosed should lie above metamorphosed what were the ages of the rocks and why did they seem to be in the wrong order 16 Why had seemingly upper and lower layers of quartzite apparently been discovered both above and below basement gneiss 17 Murchison and Nicol in the Northwest Highlands edit nbsp Roderick Murchison 1857 nbsp Murchison s Silurian concept of Loch Assynt and Quinag 1872 but published as early as 1859 In 1827 Murchison had made a cursory survey of the area from the sea but in 1855 hearing news of the discovery of fossils in the limestone at Durness he visited again with James Nicol professor of geology at Aberdeen University note 4 The fossils were thought to be Devonian and the limestone was clearly more recent than the underlying sandstone This was a problem because the sandstone later to be called Torridonian sandstone was thought to be equivalent to the Old Red Sandstone on the east coast of Scotland which certainly contained Devonian fossils 19 Because of the conditions on the ground they were unable to conduct a thorough geological survey but Murchison considered there was an ascending series becoming younger of strata exposed on the surface as one moved west to east He concluded that this exemplified the stratigraphic column of Britain The strata must dip down from west to east he thought so at any particular elevation the rocks towards the east were younger than those to the west and so he assumed the schist and gneiss of the north of Scotland were Silurian sediments above a basement 20 nbsp James Nicol James Nicol professor of geology at Aberdeen University disagreed Following a separate visit in 1856 he claimed that a geological fault ran right down along the northwest coast and that the seemingly younger rocks were in reality far older having been shifted upwards compared with those to the west note 5 2 A matter that was to become especially difficult was that Murchison considered that there were two quartzite layers of different age at two stratagraphic levels whereas Nicol claimed there was one layer but vertically displaced along the fault 22 However both geologists had to gloss over the difficulty that the quartzite was greatly folded and in some places seemed to fold over itself 23 In 1859 following another tour of the highlands when he was accompanied by his second in command at the Geological Survey Andrew Ramsay Murchison addressed a British Association in Aberdeen where he explained what he considered was the essential simplicity of the geology of the north of Scotland It seems his lecture was regarded as a triumph by the attendees and by The Times and the Scottish press 24 John Phillips spoke of the high estimation in which Murchison was held as master of the Silurian Nicol meanwhile had been preoccupied organising the geology section of the meeting his paper hardly got a mention in the press and seems to have received little support at the meeting 25 Murchison involves Geikie edit nbsp Murchison and Geikie geologising in the Scottish Highlands Prosper Merimee 1860 In 1860 Nicol returned to the Northwest Highlands to investigate further and Murchison after hearing of Nicol s travels made a quite separate journey taking along with him a junior but very ambitious member of the Survey Archibald Geikie Murchison confirmed in his own mind what he had already observed and Geikie anxious to please became a strong supporter of Murchison s views 26 However in his posthumous biography of Murchison he was to say of the expedition that Murchison stuck to his leading principle from which no amount of contradictory detail would make him swerve 27 When Nicol announced the results of his latest investigations to the Geological Society in December 1860 he refuted Murchison s findings and rejected the presence of Silurian sediments He considered igneous rock was to be found along a zone of complication from Durness to Skye and faulting was responsible for the perplexing strata He utterly rejected Murchison s idea that metamorphic rock could lie with no unconformity with no intervening period of erosion over unaltered sedimentary layers There was no evidence that the highlands were of Silurian age 28 Murchison was enraged and wrote to his protege Archibald Geikie we have a fight in which our reputation and veracity are at stake 29 In February 1861 he and Geikie delivered their paper to the Geological Society and this and Nicol s papers were published in the same volume of the Quarterly Journal of the Geological Society 30 31 nbsp Murchison s 1865 revision of his 1861 map showing a very extensive Silurian area 32 At that time the geological community in Britain had not formed a definite opinion on these matters but Murchison s view was the one that was to prevail at least for a time Murchison held great prestige and Geikie was a persuasive writer and speaker who was well able to place the best possible gloss on Murchison s views sometimes by writing favourable anonymous reviews of the two geologists own publications 33 For example Geike wrote a seemingly independent review of his and Murchison s 1861 map 34 So the Murchison Geikie view became orthodox 33 Nicol and Murchison never resolved their differences and Nicol after making little progress persuading the geological community of his theory ceased publishing on the matter after 1866 although he continued to make geological field studies in the north of Scotland throughout his career He died in 1879 35 Geikie was appointed director of the Scottish Geological Survey in 1867 and in 1871 the year of Murchison s death he was appointed to the newly created chair of Murchison professor of geology at Edinburgh University endowed by Murchison himself He continued to promulgate Murchison s Silurian theories and carried the professional geological establishment with him 36 Rising dissent in the 1880s edit nbsp Horizontal strata of Torridonian sandstone on Beinn Alligin At this time the Geological Society s members were academic geologists and amateurs some of them becoming very knowledgeable and well respected There were often differences of approach and opinion between on the one hand members of the Society and on the other senior spokesmen and managers of the professionals employed in the Geological Survey who carried out most of the actual fieldwork The Survey s directors considered themselves better informed than amateurs and academics who they regarded also as amateurs From around 1878 papers by members of the Society started to appear sometimes supporting Nicol and at other times just drawing attention to the inconsistencies in both contemporary theories and the incompatibility of the various field observations 37 Murchison retired as director general in 1867 to be succeeded by Andrew Ramsay 38 In 1880 an anonymous letter to The Times was highly critical of the state funded Survey remarking that it had been set up to be and should be a temporary organisation that it was prolonging its own existence and that the surveyors rather than being peripatetic were settling down in particular regions hence exacerbating the problem 39 The matter was debated in both Commons and Lords leading to inquiries by the Science and Art Department Ramsay by now in poor health was not well able to defend his organisation he had suggested it would take 22 years to complete the Scottish survey note 6 This led to his retirement in 1882 and a reduction in the staff and scope of the Survey s work 40 Geikie made further field trips in 1880 and 1881 and although he noted several or many anomalies he stuck with the Murchison paradigm of Silurian simplicity 41 In 1882 Wilfred Hudleston wrote of a ubiquitous but unidentified type of rock which was then being called Logan rock and is now known to be Lewisian gneiss saying this monster will in most places have to be dealt with on the basis of a fold over of some of the lower beds 42 From about 1880 the first Ordnance Survey maps of northwest Scotland started to be published and these eased the work of the geologists A few six inch maps came first followed shortly by a one inch series with contour lines 43 nbsp Charles Callaway In 1881 an amateur geologist Charles Callaway surveyed in detail the Durness and Inchnadamph regions and presented a paper to the Geological Society saying the overlying gneiss could not have been formed more recently than the unmetamorphosed limestone below it His paper generated considerable interest but little agreement except to say that the geological structure of the region was not currently understood Not deterred by a Geological Survey letter to Nature assuring that Murchison s interpretation would never be invalidated the following year Callaway ventured north again equipping him in 1883 to write according to Oldroyd one of the most important documents pertaining to the Highlands controversy Indeed in 1882 there was almost a score of geologists busy in the Highlands knowing something was there to be discovered but not knowing what it was 44 Callaway now proposed a particular stratigraphic sequence of rocks in order of the time they were originally deposited and compared this with the sequence of strata he observed in vertical sections taken along lines at different locations and in different directions He found that he could generally work out that some sequences were the right way up and that others were inverted Where a particular type of rock had seemed to be at more than one position in the stratigraphic column it now appeared it was one layer folded over on itself For Loch Eriboll Callaway claimed that over hastiness had led earlier geologists to misread the geological situation Only Nicol had seen the real structure and Callaway said he was pleased however humbly to vindicate his reputation At the meeting where Callaway presented his paper it was well received and no one from the Geological Survey rose to make any objections 45 46 Underlying the debate about geological thrusts and faults at this time was a developing world view of the earth s geology It was theorised that because the earth was cooling it was shrinking and therefore wrinkling and this was the cause of mountain building Faults formed at areas of weakness as the land collapsed into the shrinking interior In particular faults developed beside the rigid Lewisian gneiss at the coastal region of northwest Scotland 47 48 Lapworth s discoveries edit nbsp Lapworth about 1880 Southern Uplands edit nbsp Graptolite fossils from Dob s Linn From about 1869 Charles Lapworth then a schoolteacher had been quietly surveying the geology of the Southern Uplands of Scotland as a hobby There are few fossils except in some dark shale bands which are packed with the fossils of graptolites Previously geologists if they considered graptolites at all had considered them as an unreliable indicator of age whereas Lapworth identified different species at different levels Because these free floating creatures had turned to fossils in sedimentation on the sea bed this gave a good indication of the era in which each species had lived and died regardless of the prior geological stratification of the ground on which they were deposited Between about 1872 and 1877 Lapworth studied the locality known as Dob s Linn where an anticline makes it likely the five layers of dark shale have not been inverted in the immediate vicinity so knowing the order of ages of rock he could work out the order of ages of the different species 49 By applying this knowledge over the Southern Uplands as a whole he could tell that after the fossils had been laid down the land had often been severely folded sometimes to the extent of being overturned with a single geological layer being duplicated This showed that the Geological Survey s maps of the area were in error in showing the rock to be Silurian and so the Survey was forced to map the area all over again using Lapworth s detailed techniques In 1872 Lapworth had been elected as a fellow of the Geological Society he went on to become a world authority on graptolites and was appointed professor of geology and metallurgy in 1881 50 Northwest Highlands edit The Silurian theory received another setback when Lapworth examined the Northwest Highlands in 1882 and 1883 50 In 1882 Lapworth had made an inch by inch inspection and discovered that the upper and lower quartz layers were in reality part of a single layer folded over on itself and by the following year he was able to demonstrate this convincingly to colleagues At Durness and Eriboll where the layers of rock were most pronounced he could not find fossils sufficiently indicative for his purposes so he had to turn to lithostratigraphy rather than continue with the biostratigraphy he had used so successfully in the Southern Highlands Detailed examination of the lithological characteristics enabled him to build up a finely divided geological sequence and place it in the correct stratigraphical order 51 At Eriboll he recognised that it was foliation that could be observed not sedimentary bedding planes and the foliation was the result of large lateral forces from the southeast forcing older rocks to slide over younger ones 52 53 What Murchison had identified as bedding planes adjacent layers of different types and ages of rock were actually thrust planes dislocations in a layer caused by sideways thrusting having occurred 50 For many years the Highland controversy has appeared to outsiders and to those geologists who were unaware of the difficulties attending the stratigraphy of the older rocks as a trivial dispute between the Geological Survey on the one hand and a few misguided amateurs on the other Charles Lapworth On the Close of the Highland Controversy Geological Magazine 1885 54 Peach and Horne edit nbsp Horne left and Peach 1912 nbsp Glencoul Thrust Cambrian rock sandwiched between layers of older Lewisian Geikie who had been appointed director general of the Geological Survey in 1882 arranged for his colleagues Ben Peach and John Horne to make a detailed survey of the Northwest Highlands starting in 1883 with the intention of confirming Murchison s hypothesis 55 56 After only one season they were able to report that Lapworth had again been correct at least in the northern Durness Eriboll region although Geikie still saw the evidence as favouring Murchison 57 58 However by the following year after a more southerly survey Geikie became convinced when he was shown Torridonian sandstone metamorphosed to schist and he wrote in support of the new theory in his preface to Peach and Horne s 1884 report where he made first use of the term thrust plane 59 60 61 There had been no great differences of opinion between the officers of the Geological Survey out in the field and the amateur and academic geologists likewise engaged Rather it was the successive directors of the Survey Murchison Ramsay and Geikie who had been unwilling to accept that the official position was unsatisfactory By 1884 with the stratigraphy less contentious Geikie extended the remit of the survey to include the petrology of the metamorphic rocks what they had been made from in the first place 62 63 Recognising that his organisation was not strong in petrology or petrography compared with the work elsewhere in Europe particularly Germany in 1884 Geikie started approaching Jethro Teall to join the Survey and at last persuaded him in 1888 the year Teall s book British Petrography was published 64 65 note 7 By the time of Peach and Horne s 1888 paper they were able to extend their analysis of the complex stratigraphy to many more locations along the fault and by 1891 all ideas of Silurian rocks in northwest Scotland had been abandoned 67 68 So confirming Lapworth s view what Murchison had considered to be Silurian was now identified on the basis of the Durness fossils to be Cambrian and the Torridonian sandstone was placed in the later stages of the Precambrian 69 A series of geological maps was produced in this period at scales of one inch and six inches to the mile 70 note 8 Wharton Committee editIn a series of articles on scientific worthies in December 1892 Nature published an adulatory article about Geikie written by his close friend and eminent French geologist Albert Auguste de Lapparent Dealing with the Highlands Controversy it said that Murchison s theory had never quite satisfied Geikie who for his love of truth had delegated to Peach and Horne the task of making a new survey of the region without any preconceptions No mention was made of any involvement by geologists outside the Geological Survey 75 76 note 9 Soon after this an editorial article appeared in the Daily Chronicle condemning the state funded system in England that allowed eminent establishment scientists to blunder with impunity note 10 The article continued that Murchison s absurd theory had been strongly supported by Geikie who had then instituted a second survey of the whole region both carried out at the taxpayers expense Letter writing extended onto The Times and broadened to discuss the whole British scientific establishment particularly the Royal Society with suggestions of corruption 79 Geologists regarded the work in northwest Scotland as being of considerable scientific importance but the Scottish work which held little commercial significance lagged far behind that in England Wales and Ireland Politicians under pressure from both commercial and tax saving lobbies started questioning the work of the Geological Survey and there was a proposal to transfer it from the Department of Science and Art to the Ordnance Survey In 1900 a committee under John Wharton started to inquire into these matters 80 The committee found in favour of the Survey s continuance recommended improved staff pay and working conditions and a transfer to the Board of Education There was no explicit criticism of Geikie but the committee s report was likely to have led to his retirement the next year 81 Horne was interviewed by the committee and was promoted to become deputy director to Teall taking responsibility for Scotland Peach wrote an extremely generous letter on the occasion of Geikie s retirement which Geikie published in his 1924 autobiography 82 Geological Structure of the North West Highlands of Scotland edit nbsp Moine Thrust at Knockan Crag Peach and Horne continued their work and published The Geological Structure of the North West Highlands of Scotland in 1907 with Geikie in his retirement making the final editing 83 Their research was into one of the most geologically complex regions of Britain note 11 and they introduced the term Moine Thrust note 12 85 In his preface to the memoir Geikie refers the area of the Moine Thrust as being a place to study some of the more stupendous kinds of movement by which the crust of the earth has been affected 86 note 13 The introduction to the memoir written by Horne provides an accessible description of geological structure that had been uncovered Horne describes four groups of rocks dealing with them from oldest to youngest west to east First along the west coast the Lewisian complex of gneiss stretches from Cape Wrath to Loch Torridon and then out to the Hebridean islands South Rona and Raasay The topology is low rounded and hollowed only occasionally forming peaks such as at Ben Stack The rock is ancient and highly metamorphosed of igneous and occasionally sedimentary origin with many igneous dykes and sills intruding Before this was overlaid by Torridonian sandstone it was subject to immense stress towards west northwest deforming the intrusions and the heat generated produced further metamorphosis There was then a long period of erosion of what was then a land surface before the much later Torridonian sandstone sedimentation 88 Secondly the overlying Torridonian sandstones show gently inclined sedimentary strata with minor faults and joints that have eroded away to form the buttresses of high mountains No definite fossils could be found After a long period of marine erosion the rock that was laid down on top white over dark red could be dated as Cambrian indicating that the Torridonian sandstone was Precambrian Where later earth movements thrust into and over the sandstone it became metamorphosed into schist 89 nbsp Peach and Horne s illustration of trilobite Olennus fossils from northwest Scotland 90 Thirdly is a series of marine sedimentary layers quartzite dolomite and limestone within which was discovered Cambrian age trace trilobite fossils Peach and Horne remarked that the fauna are identical to those in the corresponding geological strata in North America note 14 Occasionally the sedimentary rock rests on the basement gneiss when the Torridonian sandstone had been completely eroded away such as just south of Loch Assynt These layers are separated from the underlying sandstone by an unconformity during which time interval the sandstone was folded and greatly eroded away sometimes completely The Cambrian sediment became intersected with sills and dykes particularly near Inchnadamph 93 Fourthly and what became the most interesting feature for the geologists was the immense horizontal movement of rock over all these layers that occurred subsequently towards the west northwest note 15 The underlying rock became broken up into slices that became piled up imbricated between thrust planes that also became folded Basement Lewisian gneiss could be thrust up to the surface and rock strata could be shifted around to the extent that they could become inverted in their sequence for example gneiss could overlay limestone The main thrust the Moine Thrust moved schist from the east towards and over the pre existing rock on the west while the effect of shearing at the thrust itself was to metamorphose the material at the interface into a mylonite structure In pipe rock the deformation had the effect of bending over fossilised vertical worm casts so they become flattened horizontally At one time this material extended much further to the west but it and the underlying rocks have been eroded so exposing the underlying rocks and their geological history 95 nbsp Geological cross section at Glencoul Thrust extracted from Peach amp Horne 1923 note 16 The work has been described as one of the most notable geological memoirs ever published in the English language 96 According to Butler the memoir has provided a startling synthesis describing for the first time the folds within imbricate slices and thrust sheets and the thrusts that delimit them 87 So definitive was the work that it was not until 1980 that the structural evolution of the region again started being reinvestigated including with deep seismic profiling techniques Imbricate faulting was proposed to explain the asymmetrical pattern of the stratigraphy that could not be explained by folding The 1907 memoir and its accompanying 1 inch 1 63360 geological maps have been inspiring to geologists and have given what was arguably the start of thrust belt research worldwide and showed the importance of field mapping for tectonic research 87 Afterwards edit nbsp Hebridean Terrane nbsp Moine Supergroup and Moine Thrust Belt The region of the Moine Thrust is now known to be where part of the Iapetus Ocean closed with the collision of the continents of Laurentia and Baltica about 400 million years ago The consequent Caledonian Orogeny produced intense folding and rocks of what is now called the Moine Supergroup were thrust a distance of some 100 km 60 miles over the strata at the northwest coast note 17 98 99 There is a particularly good exposure of the strata at Knockan Crag now the site of the Knockan Crag National Nature Reserve within the North West Highlands Geopark 100 nbsp Peach and Horne memorial 1930 nbsp Peach and Horne statue 2001 On the centenary of the publication of The Geological Structure the Geological Society published an article by Rob Butler discussing the book s continuing significance 87 Butler says the memoir was considered to be an instant classic and a masterpiece of regional geoscience leading to generations of geology students visiting the area now marked by a memorial to learn about the golden years of NW Highland geology 87 note 18 Much of the discussion of the geology of the Lewisian complex in the memoir is now taken for granted and it correctly identified the deformation of the intruding dykes and sills and the association between deformation and metamorphism 102 As well as the 1930 memorial at Inchnadamph a statue of the two geologists was erected at Knockan Crag in 2001 103 See also editThe Great Devonian ControversyNotes edit His sometimes sceptical colleagues sometimes referred to Murchison as the King of Siluria 6 The sandstone and quartzite have been hugely eroded until all that is left are the stumpy mountains such as Canisp and Suilven Pipe Rock is quartzite containing the traces of burrows of skolithos marine worms 13 The fossils had been discovered by Charles Peach an amateur naturalist and fossil hunter who sometimes accompanied Murchison on field trips He was the father of Ben Peach 18 Nicol supposed a somewhat vertical fault 21 Highly inclined thrust faults were yet to be discovered by Peach and Horne Ramsay estimated 21 2 years for England and Wales and 71 2 years for Ireland to complete the surveys In 1883 Thomas George Bonney had very publicly criticised the lack of knowledge of petrology shown by Geikie personally and by the Survey of which he had so recently become director general 66 For example Peach and Horne s survey of Durness and Eriboll published 1889 is on map 114 71 and a 1923 composite of the 1892 maps of Assynt was published in 1923 72 The Assynt map was reprinted in 1947 and with minor emendations in 1965 73 Since that time it has been fully revised 74 Geikie responded to this in part I was finally convinced that they were untenable by the brilliant mapping of my colleagues Messrs Peach and Horne who following Prof Lapworth s lead share with him in the glory of one of the greatest achievements of field geology in recent times 77 The editorial named Huxley Hooker and Geikie 78 Britain is itself geologically complex by world standards Peach and Horne wrote Ever since the time of Macculloch at the beginning of last century the stratigraphical position and relative age of these rocks have been a subject of animated discussion and for a time of keen controversy Relying on the apparent order of superposition the earlier observers naturally inferred from the magnificent sections laid bare along the western fjords and on the grand escarpments and dip slopes of the mountains that the Eastern Schists follow the Cambrian strata in conformable sequence But the geological structure which seems at first sight so simple has proved on later detailed examination to be extremely complicated The apparent succession has been found to be deceptive and the superposition which is undeniable is now ascertained to be due to great terrestrial displacements which have no parallel elsewhere in Britain 84 Much of the theory of thrust belts derived from the work in Peach and Horne s 1888 paper 87 67 Peach and Horne acknowledged Salter as having pointed out in 1859 that the Durness limestone fossils show greater similarity with those in America rather than Europe 91 92 The overthrusting was caused by the collision of the continents Laurentia and Baltica generating the Caledonian orogeny 94 A key to the symbols and colouring of the map is at File Glencoul Thrust 1923 key landscape png The entire map is available online 72 What Murchison had called the Eastern schists or Moine schists or gneiss because at first schist and gneiss were not clearly distinguished was later termed the Moine Supergroup 97 In his monumental work of 1909 The Face of the Eart Eduard Suess wrote the Geological Survey has issued such a masterly report by Peach and Horne and their colleagues that it may almost be said to make the mountains transparent 101 87 References editCitations edit Oldroyd 1990 pp 4 29 32 a b c Gillen 2003 p 69 Dryburgh Ross amp Thompson 2014 pp 2 12 Oldroyd 1990 pp 135 136 Oldroyd 1990 p 60 82 83 Oldroyd 1990 p 31 Oldroyd 1990 pp 29 31 Oldroyd 1990 pp 4 5 Oldroyd 1990 p 30 Oldroyd 1990 pp 49 50 Oldroyd 1990 pp 20 24 Dryburgh Ross amp Thompson 2014 p 1 Butler Rob Stratigraphic Notes The Moine Thrust Belt Leeds University Archived from the original on 10 March 2017 Retrieved 3 November 2017 Oldroyd 1990 pp 33 36 Dryburgh Ross amp Thompson 2014 p 4 Dryburgh Ross amp Thompson 2014 pp 12 14 Oldroyd 1990 p 37 Oldroyd 1990 pp 48 49 268 Oldroyd 1990 p 32 48 51 Oldroyd 1990 pp 50 51 64 Oldroyd 1990 pp 57 59 Oldroyd 1990 pp 5 68 Oldroyd 1990 pp 80 81 Oldroyd 1990 pp 74 87 Oldroyd 1990 pp 88 89 Oldroyd 1990 pp 93 121 Geikie 1875 p 238 Oldroyd 1990 pp 122 137 Oldroyd 1990 pp 139 143 Nicol 1861 pp 85 113 Murchison amp Geikie 1861 pp 171 240 Murchison Geikie amp Johnston 1865 p 31 a b Oldroyd 1990 pp 139 149 Anon Geikie 1861 pp 125 156 Oldroyd 1990 pp 43 148 149 Oldroyd 1990 pp 5 156 157 167 168 Oldroyd 1990 pp 67 68 173 188 Oldroyd 1990 p 75 Observer 22 June 1880 The Geological Survey The Times p 10 Archived from the original on 20 January 2022 Retrieved 20 January 2022 Oldroyd 1990 pp 75 267 Oldroyd 1990 pp 188 192 Oldroyd 1990 pp 202 379 White 2010 pp 505 510 Oldroyd 1990 pp 202 207 Oldroyd 1990 pp 207 213 Callaway 1883 pp 355 422 White 2010 pp 513 514 see for example Geikie 1903 pp 394 397 Oldroyd 1990 pp 217 231 a b c Oldroyd 1990 pp 219 234 Oldroyd 1990 pp 242 244 Oldroyd 1990 pp 219 234 246 247 Lapworth Charles 1883 The Secret of the Highlands Part 1 Geological Magazine 10 120 128 doi 10 1017 S0016756800164313 S2CID 248533747 Lapworth Charles 1883 The Secret of the Highlands Part 2 Geological Magazine 10 193 199 doi 10 1017 S0016756800166191 S2CID 126649782 Lapworth Charles 1883 The Secret of the Highlands Part 3 Geological Magazine 10 337 344 doi 10 1017 S0016756800166671 S2CID 197532557 Lapworth 1885a Oldroyd 1990 p 254 White 2010 p 510 Peach amp Horne 1884 pp 31 35 Oldroyd 1990 p 275 Geikie 1884 pp 29 31 Oldroyd 1990 p 278 Oldroyd 1996 pp 146 148 Oldroyd 1990 pp 258 259 276 Lapworth 1885b pp 1025 1027 Oldroyd 1990 pp 252 253 263 Teall 1888 Oldroyd 1996 p 145 a b Peach amp Horne 1888 pp 378 441 Oldroyd 1990 pp 286 293 314 Oldroyd amp Hamilton 2002 p 36 Geological Survey One Inch to the Mile 1850s 1940s National Library of Scotland National Library of Scotland maps Geological Survey Ordnance Survey Archived from the original on 28 January 2022 Retrieved 28 January 2022 Geological Survey Six Inch to the Mile 1850s 1940s National Library of Scotland National Library of Scotland maps Geological Survey Ordnance Survey Archived from the original on 28 January 2022 Retrieved 28 January 2022 Sheet 114 Tongue Solid and drift edition National Library of Scotland maps Geological Survey Ordnance Survey 1889 Archived from the original on 28 January 2022 Retrieved 28 January 2022 a b Parts of sheets 107 108 101 102 Assynt district National Library of Scotland maps Geological Survey Ordnance Survey 1892 1923 Archived from the original on 28 January 2022 Retrieved 28 January 2022 Oldroyd 1990 p 283 Assynt B Special Sheet Folded Map British Geological Survey 2007 ISBN 9780751835120 Archived from the original on 3 February 2022 Retrieved 3 February 2022 de Lapparent 1893 pp 217 220 Hamilton 1991 pp 63 64 Geikie 1893 pp 292 293 Hamilton 1991 p 68 Hamilton 1991 pp 68 73 Oldroyd 1996 pp 307 321 Oldroyd 1996 pp 323 324 Oldroyd 1996 pp 326 328 Oldroyd 1996 p 271Peach amp Horne 1907 Peach amp Horne 1907 p 1 Peach amp Horne 1907 pp 8 466 471Oldroyd 1990 p 281 Butler 2007 Peach amp Horne 1907 p vi a b c d e f Butler 2007 Peach amp Horne 1907 pp 1 4 Peach amp Horne 1907 pp 4 6 Peach amp Horne 1892 pp 240 241 Peach amp Horne 1907 p 376 Dalziel 2010 p 189 Peach amp Horne 1907 pp 5 7 375 376 Johnstone amp Mykura 1989 pp 10 11 Peach amp Horne 1907 pp 7 10 Dryburgh Ross amp Thompson 2014 p 15 Strachan amp Holdsworth 2010 p 233 Ross 1991 pp 26 28 Johnstone amp Mykura 1989 pp 9 11 49 55 Breckenridge Jan 2007 The Story of Knockan Crag National Nature Reserve PDF Scotland s National Nature Reserves Archived PDF from the original on 25 May 2021 Retrieved 12 March 2022 Suess 1909 p 529 Butler 2007 Law amp Butler 2010 pp 1 5 Monument to Geologists Ben Peach 1842 1926 and John Horne 1848 1928 Art UK Discover Artworks Art UK 2013 Archived from the original on 12 March 2022 Retrieved 12 March 2022 Works cited edit Anon Geikie 1861 Art VI Recent Discoveries in Scottish Geology The North British Review 35 125 156 Butler Rob 2007 Peach and Horne the memoir at 100 Geoscientist 17 1 The Geological Society of London Callaway Charles 1883 The Age of the Newer Gneissic Rocks of the Northern Highlands The Quarterly Journal of the Geological Society of London 39 1 4 355 422 doi 10 1144 GSL JGS 1883 039 01 04 24 S2CID 140678182 with a brief preemptive paper Callaway Charles 1883 The Highland Problem Geological Magazine 10 3 139 140 Bibcode 1883GeoM 10 139C doi 10 1017 S0016756800164362 ISSN 1469 5081 S2CID 129021620 Dalziel Ian W D 2010 The North West Highlands memoir a century old legacy for understanding Earth before Pangaea Geological Society London Special Publications 335 1 189 205 Bibcode 2010GSLSP 335 189D doi 10 1144 sp335 9 S2CID 129235161 Dryburgh P M Ross S M Thompson C L 2014 Assynt the Geologists Mecca Edinburgh Geological Society ISBN 9780904440140 Geikie Archibald 1875 Life of Sir Roderick I Murchison bart K C B F R S sometime director general of the Geological survey of the United Kingdom Based of his journals and letters with notices of his scientific contemporaries and a sketch of the rise and growth of palaeozoic geology in Britain Vol II London John Murray Geikie Archibald November 1884 The Crystalline Rocks of the Scottish Highlands Nature 31 785 29 31 Bibcode 1884Natur 31 29G doi 10 1038 031029d0 S2CID 4134079 It would require more space than can be given in these pages to do justice to the views of those geologists from Nicol downwards by whom Murchison s sections have been criticised and to show how far the conclusions to which the Geological Survey has been led have been anticipated Geikie Archibald January 1893 The Geology of the North west Highlands Nature 47 1213 292 293 Bibcode 1893Natur 47 292G doi 10 1038 047292c0 ISSN 1476 4687 S2CID 3971276 Geikie Archibald 1903 The Text Book Of Geology Volume I London Macmillan Gillen Con 2003 The Highlands Controversy Geology and landscapes of Scotland Harpenden Terra Publishing ISBN 1 903544 09 2 de Lapparent A January 1893 Scientific Worthies Nature 47 1210 217 220 Bibcode 1893Natur 47 217D doi 10 1038 047217a0 S2CID 186242888 Hamilton Beryl M 1991 A Geological Blunder 1893 A Scientific Storm in a Journalistic Teacup Notes and Records of the Royal Society of London 45 1 63 77 doi 10 1098 rsnr 1991 0003 ISSN 0035 9149 JSTOR 531521 S2CID 143857779 Johnstone G S Mykura W 1989 British Regional Geology the Northern Highlands 4th ed Her Majesty s Stationery Office ISBN 0 11 884460 1 Lapworth Charles 1885a On the Close of the Highland Controversy Geological Magazine 2 3 97 106 Bibcode 1885GeoM 2 97L doi 10 1017 S0016756800005458 S2CID 131045660 Lapworth Charles 1885b The Highland Controversy in British Geology its Causes Course and Consequences Report of the Fifty fifth Meeting of the British Association for the Advancement if Science Held at Aberdeen in September 1885 1025 1027 Law R D Butler R W H Holdsworth R E Krabbendam M Strachan R A 2010 Continental tectonics and mountain building The legacy of Peach and Horne an introduction Geological Society London Special Publications 335 1 1 5 Bibcode 2010GSLSP 335 1L doi 10 1144 SP335 1 S2CID 128967800 Murchison Roderick Geikie Archibald 1861 On the Altered Rocks of the Western Islands of Scotland and the North western and Central Highlands The Quarterly Journal of the Geological Society of London 17 1 2 171 240 doi 10 1144 GSL JGS 1861 017 01 02 21 S2CID 140142272 alternative source at Internet Archive Murchison Roderick Impey Geikie Archibald Johnston Alexander Keith 1865 New Geological Map of Scotland Edinburgh W amp A K Johnston Blackwood amp Sons Nicol James 1861 On the Structure of the North western Highlands and the Relation of the Gneiss Red Sandstone and Quartzite of Sutherland and Ross shire The Quarterly Journal of the Geological Society of London 17 1 2 85 113 doi 10 1144 GSL JGS 1861 017 01 02 11 S2CID 140663553 alternative source at Internet Archive Oldroyd David R 1990 The Highlands Controversy Constructing Geological Knowledge through Fieldwork in Nineteenth Century Britain Chicago and London the University of Chicago press ISBN 0 226 62635 0 Oldroyd made some updates to his account at Oldroyd 1996 Oldroyd David 1996 Sir Archibald Geikie 1835 1924 and the Highlands Controversy New archival sources for the History of British Geology in the Nineteenth Century Earth Sciences History 15 2 141 150 doi 10 17704 eshi 15 2 k64075116m370702 ISSN 0736 623X JSTOR 24138467 Oldroyd D R Hamilton B M 2002 2 Themes in the early history of Scottish geology In Trewin N H ed The Geology of Scotland Geological Society of London pp 22 44 ISBN 978 1 86239 126 0 Page David Lapworth Charles 1883 Advanced Text book of Physical Geography William Blackwood amp Sons p 39 Peach B N Horne John 13 November 1884 Report on the Geology of the North West of Sutherland PDF Nature 31 785 31 35 Bibcode 1884Natur 31 31P doi 10 1038 031031a0 S2CID 4142467 Peach B N Horne J Gunn W Clough C T Hinxman L Cadell H M 1 January 1888 Report on the Recent Work of the Geological Survey in the North west Highlands of Scotland based on the Field notes and Maps Read April 25 1888 Quarterly Journal of the Geological Society 44 1 4 378 441 doi 10 1144 GSL JGS 1888 044 01 04 34 S2CID 129572998 Peach B N Horne J 1 January 1892 The Olenellus Zone in the North west Highlands of Scotland Quarterly Journal of the Geological Society 48 1 4 227 242 doi 10 1144 gsl jgs 1892 048 01 04 17 S2CID 140197589 Peach Benjamin Horne John Gunn William Clough Charles Hinxman Lionel Teall Jethro 1907 Geikie Archibald ed The Geological Structure of the North west Highlands of Scotland H M Stationery Office alternative source at Internet Archive Peach B N Horne J Clough C T Hinxman L W Cadell H M Dinham C H 1923 BGS Assynt Special Sheet www largeimages bgs ac uk British Geological Survey copyright NERC This map is linked to from Gateway to the Earth Record details Assynt district www bgs ac uk British Geological Survey Retrieved 5 November 2017 Ross S 1991 The Geology of Sutherland In Omand Donald ed The Sutherland Book Golspie Northern Times ISBN 1 873610 00 9 Strachan R A Holdsworth R E Krabbendam M Alsop G I 2010 The Moine Supergroup of NW Scotland insights into the analysis of polyorogenic supracrustal sequences Geological Society London Special Publications 335 1 233 254 Bibcode 2010GSLSP 335 233S doi 10 1144 SP335 11 S2CID 129225043 Suess Eduard 1909 Part V The Face of the Earth continued The Face Of The Earth Vol 4 Translated by Sollas Hertha B C Sollas Hertha W J p 529 Teall J J H 1888 British petrography with special reference to the igneous rocks London Dulau White S H 2010 Mylonites lessons from Eriboll Geological Society London Special Publications 335 1 505 542 Bibcode 2010GSLSP 335 505W doi 10 1144 sp335 22 hdl 1874 252920 S2CID 140564848 Further reading edit Bentley Callan 19 April 2017 Travels in Geology Geo diversity and geologic history in the North West Highlands of Scotland Earth American Geosciences Institute Butler Robert W H 2010 The Geological Structure of the North West Highlands of Scotland revisited Peach et al 100 years on Geological Society London Special Publications 335 1 7 27 Bibcode 2010GSLSP 335 7B doi 10 1144 SP335 2 S2CID 129335860 Murchison Roderick Impey 1854 Siluria a history of the oldest rocks containing organic remains 1 ed London John Murray The Highlands Controversy North West Highlands Geopark Retrieved 13 March 2022 and subsequent linked pages Retrieved from https en wikipedia org w index php title Highlands controversy of Northwest Scotland amp oldid 1218661945, wikipedia, wiki, book, books, library,

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