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The Highlands controversy was a
scientific controversy
Controversies involving science exists in all aspects. Sometimes defined as a "''persistent disagreement''" over knowledge, the contrasting opinions of certain topics leaves individuals in a tense setting.
A scientific controversy is a substanti ...
which started between British geologists in the middle of the nineteenth century concerning the nature of the
rock strata
In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ei ...
in the
Northwest Highlands
The Northwest Highlands are located in the northern third of Scotland that is separated from the Grampian Mountains by the Great Glen (Glen More). The region comprises Wester Ross, Assynt, Sutherland and part of Caithness. The Caledonian Canal, ...
of
Scotland
Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to the ...
. The debate became contentious, even acrimonious, because of some of the personalities involved and because it pitted professional geologists of the
Geological Survey
A geological survey is the systematic investigation of the geology beneath a given piece of ground for the purpose of creating a geological map or model. Geological surveying employs techniques from the traditional walk-over survey, studying outc ...
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
The Moine Thrust Belt or Moine Thrust Zone is a linear tectonic feature in the Scottish Highlands which runs from Loch Eriboll on the north coast south-west to the Sleat peninsula on the Isle of Skye. The thrust belt consists of a series of t ...
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''.
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
Sir Archibald Geikie (28 December 183510 November 1924) was a Scottish geologist and writer.
Early life
Geikie was born in Edinburgh in 1835, the eldest son of Isabella Thom and her husband James Stuart Geikie, a musician and music critic. T ...
, 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
The Geological Society of London, known commonly as the Geological Society, is a learned society based in the United Kingdom. It is the oldest national geological society in the world and the largest in Europe with more than 12,000 Fellows.
Fe ...
and the
Royal Society
The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...
and to receive the
Order of Merit
The Order of Merit (french: link=no, Ordre du Mérite) is an order of merit for the Commonwealth realms, recognising distinguished service in the armed forces, science, art, literature, or for the promotion of culture. Established in 1902 by K ...
.
The northwest highlands region of Scotland is now known to be where part of the
Iapetus Ocean
The Iapetus Ocean (; ) was an ocean that existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale (between 600 and 400 million years ago). The Iapetus Ocean was situated in the southern hemisphere, between the paleoco ...
closed with the collision of the continents of
Laurentia
Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, although ...
and
Baltica
Baltica is a paleocontinent that formed in the Paleoproterozoic and now constitutes northwestern Eurasia, or Europe north of the Trans-European Suture Zone and west of the Ural Mountains.
The thick core of Baltica, the East European Craton, is mo ...
about 400 million years ago. The consequent
Caledonian Orogeny
The Caledonian orogeny was a mountain-building era recorded in the northern parts of the British Isles, the Scandinavian Mountains, Svalbard, eastern Greenland and parts of north-central Europe. The Caledonian orogeny encompasses events that occ ...
produced intense folding and compression of rocks – at
thrust faults
A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks.
Thrust geometry and nomenclature
Reverse faults
A thrust fault is a type of reverse fault that has a dip of 45 degrees or less.
If ...
older rock strata slid for miles over younger rocks and, at
nappe
In geology, a nappe or thrust sheet is a large sheetlike body of rock (geology), rock that has been moved more than or above a thrust fault from its original position. Nappes form in compressional tectonic settings like continental collision z ...
s, the sequences of rock strata became inverted and duplicated at overturned
anticline
In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the ...
s.
Background
Geological science in the mid nineteenth century
File:Geological column, late 19th century.svg, upDerived from
''(clickable image)''
rect 15 2 191 47 Geologic time scale
The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochrono ...
rect 38 47 170 80 Mesozoic
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...
rect 69 80 170 115 Permian
The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...
rect 69 115 170 158 Carboniferous
The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...
rect 69 157 170 197 Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...
rect 69 197 170 237 Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...
rect 69 238 170 275 Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...
rect 69 275 170 312 Cambrian
The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...
rect 38 312 170 344 Precambrian
The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...
rect 38 80 170 312 Paleozoic
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon.
The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838
by combining the Greek words ''palaiós'' (, "old") and ' ...
default
From around 1830 geologists were beginning to date rocks according to the embedded fossils. The
law of superposition
The law of superposition is an axiom that forms one of the bases of the sciences of geology, archaeology, and other fields pertaining to geological stratigraphy. In its plainest form, it states that in undeformed stratigraphic sequences, the ...
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
Arnold Escher von der Linth (8 June 1807 in Zürich12 July 1872) was a Swiss geologist, the son of Hans Conrad Escher von der Linth (1767–1823).
He made the first ascent of the Lauteraarhorn on 8 August 1842 together with Pierre Jean Édouard D ...
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
Albert Heim (12 April 184931 August 1937) was a Swiss geologist, noted for his three-volume ''Geologie der Schweiz''.
Born in Zürich, he was educated at Zürich and Berlin universities. Very early in life he became interested in the physical fe ...
published the findings in 1878.
Thrust fault
A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks.
Thrust geometry and nomenclature
Reverse faults
A thrust fault is a type of reverse fault that has a dip of 45 degrees or less.
If ...
ing, where there is a considerable horizontal movement of younger strata over older, had not yet been identified.
Roderick Murchison
Sir Roderick Impey Murchison, 1st Baronet, (19 February 1792 – 22 October 1871) was a Scotland, Scottish geologist who served as director-general of the British Geological Survey from 1855 until his death in 1871. He is noted for investigat ...
's expedition to Wales in 1831 led to his identification of the
Silurian period
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...
and he came to regard the Silurian
geological system as being his own territory. 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
Adam Sedgwick (; 22 March 1785 – 27 January 1873) was a British geologist and Anglican priest, one of the founders of modern geology. He proposed the Cambrian and Devonian period of the geological timescale. Based on work which he did on W ...
who had previously identified the rocks as
Cambrian
The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...
− the intervening
Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...
period was yet to be characterised. Murchison identified the Silurian on the basis of the types of fossils the rocks contained whereas earlier geologists had studied the type of rock. The strength of Murchison's views became buttressed by his knighthood in 1846 and when he was appointed director-general of the
Geological Survey
A geological survey is the systematic investigation of the geology beneath a given piece of ground for the purpose of creating a geological map or model. Geological surveying employs techniques from the traditional walk-over survey, studying outc ...
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.
Northwest Highlands of Scotland
The Northwest Highlands were, and still are, remote and difficult to access. Along a coastal strip some long and wide the terrain is austere with isolated mountains rising above barren lower ground where
knolls of bare rock lie among
lochan
''Loch'' () is the Scottish Gaelic, Scots and Irish word for a lake or sea inlet. It is cognate with the Manx lough, Cornish logh, and one of the Welsh words for lake, llwch.
In English English and Hiberno-English, the anglicised spellin ...
s and
peat bog
A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and muskeg; a ...
s. This geological region runs from the
Sleat peninsula of
Skye
The Isle of Skye, or simply Skye (; gd, An t-Eilean Sgitheanach or ; sco, Isle o Skye), is the largest and northernmost of the major islands in the Inner Hebrides of Scotland. The island's peninsulas radiate from a mountainous hub dominated b ...
northward through
Kyle of Lochalsh
Kyle of Lochalsh (from the Scottish Gaelic, Gaelic ''Caol Loch Aillse'', "strait of the foaming loch") is a village in the historic county of Ross-shire on the northwest coast of Scotland, located around west-southwest of Inverness. It is loca ...
,
Ullapool
Ullapool (; gd, Ulapul ) is a village and port located in Northern Scotland. Ullapool has a population of around 1,500 inhabitants. It is located around northwest of Inverness in Ross and Cromarty, Scottish Highlands. Despite its modest size, ...
and
Assynt
Assynt ( gd, Asainn or ) is a sparsely populated area in the south-west of Sutherland, lying north of Ullapool on the west coast of Scotland. Assynt is known for its landscape and its remarkable mountains, which have led to the area, along with ...
to
Cape Wrath
Cape Wrath ( gd, Am Parbh, known as ' in Lewis) is a cape in the Durness parish of the county of Sutherland in the Highlands of Scotland. It is the most north-westerly point in mainland Britain.
The cape is separated from the rest of the mai ...
and
Loch Eriboll
__NOTOC__
Loch Eriboll (Scottish Gaelic: "Loch Euraboil") is a long sea loch on the north coast of Scotland, which has been used for centuries as a deep water anchorage as it is safe from the often stormy seas of Cape Wrath and the Pentland Firt ...
.
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
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...
rock –
Lewisian gneiss
The Lewisian complex or Lewisian gneiss is a suite of Precambrian metamorphic rocks that outcrop in the northwestern part of Scotland, forming part of the Hebridean Terrane and the North Atlantic Craton. These rocks are of Archaean and Paleoprote ...
, the oldest rock in Britain. Above this
basement
A basement or cellar is one or more floors of a building that are completely or partly below the ground floor. It generally is used as a utility space for a building, where such items as the furnace, water heater, breaker panel or fuse box, ...
are less-disturbed
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates) ...
s,
quartzite
Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tect ...
and some
Durness limestone. No fossils are to be found in the sandstone; the quartzite contained "
Pipe Rock
''Skolithos'' (formerly spelled ''Scolithus'' or ''Skolithus'') is a common trace fossil ichnogenus that is, or was originally, an approximately vertical cylindrical burrow. It is produced by a variety of organisms in shallow marine environment ...
" but at the time this was not recognised as containing fossils; and the fossils in the limestone could not be unambiguously dated at the time. Away to the east of the coastal strip are the strongly metamorphosed
Moine rocks which in places lie above non-metamorphosed strata.
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? Why had seemingly upper and lower layers of quartzite apparently been discovered both above and below basement gneiss?
Murchison and Nicol in the Northwest Highlands
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
Durness ( gd, Diùranais) is a village and civil parish in the north-west Highlands of Scotland. It lies on the north coast of the country in the traditional county of Sutherland, around north of Inverness. The area is remote, and the parish is ...
, he visited again with
James Nicol, professor of geology at
Aberdeen University
, mottoeng = The fear of the Lord is the beginning of wisdom
, established =
, type = Public research universityAncient university
, endowment = £58.4 million (2021)
, budget ...
. The fossils were thought to be
Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...
and the limestone was clearly more recent than the underlying sandstone. This was a problem because the sandstone, later to be called
Torridonian sandstone
In geology, the term Torridonian is the informal name for the Torridonian Group, a series of Mesoproterozoic to Neoproterozoic arenaceous and argillaceous sedimentary rocks, which occur extensively in the Northwest Highlands of Scotland. The st ...
, was thought to be equivalent to the
Old Red Sandstone
The Old Red Sandstone is an assemblage of rocks in the North Atlantic region largely of Devonian age. It extends in the east across Great Britain, Ireland and Norway, and in the west along the northeastern seaboard of North America. It also exte ...
on the east coast of Scotland which certainly contained Devonian fossils. 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
A stratigraphic column is a representation used in geology and its subfield of stratigraphy to describe the vertical location of rock units in a particular area. A typical stratigraphic column shows a sequence of sedimentary rocks, with the oldest ...
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
Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand a ...
above a
basement
A basement or cellar is one or more floors of a building that are completely or partly below the ground floor. It generally is used as a utility space for a building, where such items as the furnace, water heater, breaker panel or fuse box, ...
.
James Nicol, professor of geology at
Aberdeen University
, mottoeng = The fear of the Lord is the beginning of wisdom
, established =
, type = Public research universityAncient university
, endowment = £58.4 million (2021)
, budget ...
disagreed. Following a separate visit in 1856 he claimed that a
geological fault
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...
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. 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. However both geologists had to gloss over the difficulty that the quartzite was greatly folded and in some places seemed to fold over itself.
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
The British Science Association (BSA) is a charity and learned society founded in 1831 to aid in the promotion and development of science. Until 2009 it was known as the British Association for the Advancement of Science (BA). The current Chie ...
in
Aberdeen
Aberdeen (; sco, Aiberdeen ; gd, Obar Dheathain ; la, Aberdonia) is a city in North East Scotland, and is the third most populous city in the country. Aberdeen is one of Scotland's 32 local government council areas (as Aberdeen City), and ...
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
''The Times'' is a British daily national newspaper based in London. It began in 1785 under the title ''The Daily Universal Register'', adopting its current name on 1 January 1788. ''The Times'' and its sister paper ''The Sunday Times'' (fou ...
'' and the Scottish press.
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.
Murchison involves Geikie
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
Sir Archibald Geikie (28 December 183510 November 1924) was a Scottish geologist and writer.
Early life
Geikie was born in Edinburgh in 1835, the eldest son of Isabella Thom and her husband James Stuart Geikie, a musician and music critic. T ...
. Murchison confirmed in his own mind what he had already observed and Geikie, anxious to please, became a strong supporter of Murchison's views. 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".
When Nicol announced the results of his latest investigations to the
Geological Society
The Geological Society of London, known commonly as the Geological Society, is a learned society based in the United Kingdom. It is the oldest national geological society in the world and the largest in Europe with more than 12,000 Fellows.
Fe ...
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
Durness ( gd, Diùranais) is a village and civil parish in the north-west Highlands of Scotland. It lies on the north coast of the country in the traditional county of Sutherland, around north of Inverness. The area is remote, and the parish is ...
to
Skye
The Isle of Skye, or simply Skye (; gd, An t-Eilean Sgitheanach or ; sco, Isle o Skye), is the largest and northernmost of the major islands in the Inner Hebrides of Scotland. The island's peninsulas radiate from a mountainous hub dominated b ...
and faulting was responsible for the perplexing strata. He utterly rejected Murchison's idea that metamorphic rock could lie with no
unconformity
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval o ...
(with no intervening period of erosion) over unaltered sedimentary layers. There was no evidence that the highlands were of Silurian age. Murchison was enraged and wrote to his protegé
Archibald Geikie
Sir Archibald Geikie (28 December 183510 November 1924) was a Scottish geologist and writer.
Early life
Geikie was born in Edinburgh in 1835, the eldest son of Isabella Thom and her husband James Stuart Geikie, a musician and music critic. T ...
"we have a fight in which our reputation and veracity are at stake". 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
The ''Journal of the Geological Society '' is a peer-reviewed scientific journal published by the Geological Society of London. It covers research in all aspects of the Earth sciences.
References
External links
* Proceedings of the Geologica ...
''.
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. For example, Geike wrote a seemingly independent review of his and Murchison's 1861 map. So, the Murchison–Geikie view became orthodox.
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.
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
The University of Edinburgh ( sco, University o Edinburgh, gd, Oilthigh Dhùn Èideann; abbreviated as ''Edin.'' in post-nominals) is a public research university based in Edinburgh, Scotland. Granted a royal charter by King James VI in 1582 ...
, endowed by Murchison himself. He continued to promulgate Murchison's Silurian theories and carried the professional geological establishment with him.
Rising dissent in the 1880s
At this time the
Geological Society
The Geological Society of London, known commonly as the Geological Society, is a learned society based in the United Kingdom. It is the oldest national geological society in the world and the largest in Europe with more than 12,000 Fellows.
Fe ...
'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
A geological survey is the systematic investigation of the geology beneath a given piece of ground for the purpose of creating a geological map or model. Geological surveying employs techniques from the traditional walk-over survey, studying outc ...
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.
Murchison retired as director-general in 1867 to be succeeded by
Andrew Ramsay. In 1880 an anonymous letter to ''
The Times
''The Times'' is a British daily national newspaper based in London. It began in 1785 under the title ''The Daily Universal Register'', adopting its current name on 1 January 1788. ''The Times'' and its sister paper ''The Sunday Times'' (fou ...
'' 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. The matter was debated in both
Commons
The commons is the cultural and natural resources accessible to all members of a society, including natural materials such as air, water, and a habitable Earth. These resources are held in common even when owned privately or publicly. Commons ...
and
Lords
Lords may refer to:
* The plural of Lord
Places
*Lords Creek, a stream in New Hanover County, North Carolina
* Lord's, English Cricket Ground and home of Marylebone Cricket Club and Middlesex County Cricket Club
People
*Traci Lords (born 1 ...
leading to inquiries by the
Science and Art Department
The Science and Art Department was a British government body which functioned from 1853 to 1899, promoting education in art, science, technology and design in Britain and Ireland.
Background
The Science and Art Department was created as a subdivis ...
. 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. This led to his retirement in 1882 and a reduction in the staff and scope of the Survey's work.
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. 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
The Lewisian complex or Lewisian gneiss is a suite of Precambrian metamorphic rocks that outcrop in the northwestern part of Scotland, forming part of the Hebridean Terrane and the North Atlantic Craton. These rocks are of Archaean and Paleoprote ...
, 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". From about 1880 the first
Ordnance Survey
, nativename_a =
, nativename_r =
, logo = Ordnance Survey 2015 Logo.svg
, logo_width = 240px
, logo_caption =
, seal =
, seal_width =
, seal_caption =
, picture =
, picture_width =
, picture_caption =
, formed =
, preceding1 =
, di ...
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.
In 1881 an amateur geologist
Charles Callaway surveyed in detail the
Durness
Durness ( gd, Diùranais) is a village and civil parish in the north-west Highlands of Scotland. It lies on the north coast of the country in the traditional county of Sutherland, around north of Inverness. The area is remote, and the parish is ...
and
Inchnadamph
Inchnadamph is a hamlet in Assynt, Sutherland, Scotland. The name is an anglicisation of the Gaelic name Innis nan Damh meaning 'meadow of the stags'. Assynt is a remote area with a low population density. Inchnadamph contains a few houses, a l ...
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
Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. ...
'' 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.
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
__NOTOC__
Loch Eriboll (Scottish Gaelic: "Loch Euraboil") is a long sea loch on the north coast of Scotland, which has been used for centuries as a deep water anchorage as it is safe from the often stormy seas of Cape Wrath and the Pentland Firt ...
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.
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.
Lapworth's discoveries
Southern Uplands
From about 1869,
Charles Lapworth
Charles Lapworth FRS FGS (20 September 1842 – 13 March 1920) was a headteacher and an English geologist who pioneered faunal analysis using index fossils and identified the Ordovician period.
Biography
Charles Lapworth was born at Faring ...
, then a schoolteacher, had being quietly surveying the geology of the
Southern Uplands
The Southern Uplands ( gd, Na Monaidhean a Deas) are the southernmost and least populous of mainland Scotland's three major geographic areas (the other two being the Central Lowlands and the Grampian Mountains and the Highlands, as illustrated ...
of Scotland as a hobby. There are few fossils except in some dark
shale
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...
bands which are packed with the fossils of
graptolites
Graptolites are a group of colonial animals, members of the subclass Graptolithina within the class Pterobranchia. These filter-feeding organisms are known chiefly from fossils found from the Middle Cambrian (Miaolingian, Wuliuan) through the L ...
. 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
Dob's Linn is a small steep valley in Dumfries and Galloway, just north of the A708 road between Moffat and Selkirk, in Scotland. It is part of the Grey Mare's Tail Nature Reserve which is owned by the National Trust for Scotland. According to ...
where an
anticline
In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the ...
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.
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.
Northwest Highlands
The Silurian theory received another setback when Lapworth examined the Northwest Highlands in 1882 and 1883. 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
Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology.
In general, strata are primarily igneo ...
rather than continue with the
biostratigraphy
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock Stratum, strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictiona ...
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. At Eriboll he recognised that it was
foliation
In mathematics (differential geometry), a foliation is an equivalence relation on an ''n''-manifold, the equivalence classes being connected, injectively immersed submanifolds, all of the same dimension ''p'', modeled on the decomposition of ...
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.
What Murchison had identified as
bedding plane
In geology, a bed is a layer of sediment, sedimentary rock, or pyroclastic material "bounded above and below by more or less well-defined bedding surfaces".Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds., 2005. ''Glossary of Geology'' ...
s – adjacent layers of different types and ages of rock – were actually
thrust planes – dislocations in a layer caused by sideways thrusting having occurred.
Peach and Horne
Geikie, who had been appointed director-general of the Geological Survey in 1882, arranged for his colleagues
Ben Peach
Benjamin Neeve Peach (6 September 1842 – 29 January 1926) was a British geologist.
Life
Peach was born at Gorran Haven in Cornwall on 6 September 1842 to Jemima Mabson and Charles William Peach, an amateur British naturalist and geologist. ...
and
John Horne
John Horne PRSE FRS FRSE FEGS LLD (1 January 1848 – 30 May 1928) was a Scottish geologist. He served as President of the Royal Society of Edinburgh from 1915 to 1919.
Life
Horne was born on 1 January 1848, in Campsie, Stirlingshire, the ...
to make a detailed survey of the Northwest Highlands starting in 1883 with the intention of confirming Murchison's hypothesis. 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. 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".
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
Petrology () is the branch of geology that studies rocks and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology. Igneous and metamorphic petrology are commonly taught together ...
of the metamorphic rocks – what they had been made from in the first place. Recognising that his organisation was not strong in petrology or
petrography
Petrography is a branch of petrology that focuses on detailed descriptions of rocks. Someone who studies petrography is called a petrographer. The mineral content and the textural relationships within the rock are described in detail. The classi ...
compared with the work elsewhere in Europe, particularly Germany, in 1884 Geikie started approaching
Jethro Teall
Sir Jethro Justinian Harris Teall Royal Society of London, FRS HFRSE PGS (5 January 1849 – 2 July 1924) was a UK, British geologist and petrography, petrographist.
Teallite is named after him.
Life
He was born to Jethro Teall of Sandwich, Ke ...
to join the Survey and at last persuaded him in 1888, the year Teall's book ''British Petrography'' was published. 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. 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. A series of geological maps was produced in this period at scales of one inch and six inches to the mile.
Wharton Committee
In a series of articles on "scientific worthies", in December 1892 ''
Nature
Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. ...
'' published an adulatory article about Geikie, written by his close friend and eminent French geologist
Albert Auguste de Lapparent
Albert Auguste Cochon de Lapparent (30 December 18395 May 1908) was a French geologist.
Life
He was born at Bourges. After studying at the École polytechnique from 1858 to 1860 he became ''ingénieur au corps des mines'', and took part in drawi ...
. 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. Soon after this an editorial article appeared in the ''
Daily Chronicle
The 'Daily Chronicle' was a British newspaper that was published from 1872 to 1930 when it merged with the ''Daily News (UK), Daily News'' to become the ''News Chronicle''.
Foundation
The ''Daily Chronicle'' was developed by Edward Lloyd (publis ...
'' condemning the state-funded system in England that allowed eminent establishment scientists to "blunder with impunity". 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
''The Times'' is a British daily national newspaper based in London. It began in 1785 under the title ''The Daily Universal Register'', adopting its current name on 1 January 1788. ''The Times'' and its sister paper ''The Sunday Times'' (fou ...
'' and broadened to discuss the whole British scientific establishment, particularly the
Royal Society
The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...
, with suggestions of corruption.
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
The Science and Art Department was a British government body which functioned from 1853 to 1899, promoting education in art, science, technology and design in Britain and Ireland.
Background
The Science and Art Department was created as a subdivis ...
to the
Ordnance Survey
, nativename_a =
, nativename_r =
, logo = Ordnance Survey 2015 Logo.svg
, logo_width = 240px
, logo_caption =
, seal =
, seal_width =
, seal_caption =
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, di ...
. In 1900 a committee under
John Wharton started to inquire into these matters. 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
A board of education, school committee or school board is the board of directors or board of trustees of a school, local school district or an equivalent institution.
The elected council determines the educational policy in a small regional are ...
. There was no explicit criticism of Geikie but the committee's report was likely to have led to his retirement the next year. 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.
''Geological Structure of the North-West Highlands of Scotland''
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. Their research was into one of the most geologically complex regions of Britain, and they introduced the term "
Moine Thrust
The Moine Thrust Belt or Moine Thrust Zone is a linear tectonic feature in the Scottish Highlands which runs from Loch Eriboll on the north coast south-west to the Sleat peninsula on the Isle of Skye. The thrust belt consists of a series of t ...
". 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".
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
The Lewisian complex or Lewisian gneiss is a suite of Precambrian metamorphic rocks that outcrop in the northwestern part of Scotland, forming part of the Hebridean Terrane and the North Atlantic Craton. These rocks are of Archaean and Paleoprote ...
of
gneiss
Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures an ...
stretches from
Cape Wrath
Cape Wrath ( gd, Am Parbh, known as ' in Lewis) is a cape in the Durness parish of the county of Sutherland in the Highlands of Scotland. It is the most north-westerly point in mainland Britain.
The cape is separated from the rest of the mai ...
to
Loch Torridon
Loch Torridon ( gd, Loch Thoirbheartan) is a sea loch on the west coast of Scotland in the Northwest Highlands. The loch was created by glacial processes and is in total around 15 miles (25 km) long. It has two sections: Upper Loch Torridon ...
and then out to the
Hebridean
The Hebrides (; gd, Innse Gall, ; non, Suðreyjar, "southern isles") are an archipelago off the west coast of the Scottish mainland. The islands fall into two main groups, based on their proximity to the mainland: the Inner Hebrides, Inner a ...
islands
South Rona
Rona ( gd, Rònaigh), sometimes called South Rona to distinguish it from North Rona (a small uninhabited island to the northwest of Cape Wrath), is an inhabited island in the Inner Hebrides. It lies between the Sound of Raasay and the Inner So ...
and
Raasay
Raasay (; gd, Ratharsair) or the Isle of Raasay is an island between the Isle of Skye and the mainland of Scotland. It is separated from Skye by the Sound of Raasay and from Applecross by the Inner Sound. It is famous for being the birt ...
. 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.
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
The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...
, indicating that the Torridonian sandstone was
Precambrian
The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...
. Where later earth movements thrust into and over the sandstone it became metamorphosed into
schist
Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes o ...
.
Thirdly is a series of marine sedimentary layers –
quartzite
Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tect ...
,
dolomite Dolomite may refer to:
*Dolomite (mineral), a carbonate mineral
*Dolomite (rock), also known as dolostone, a sedimentary carbonate rock
*Dolomite, Alabama, United States, an unincorporated community
*Dolomite, California, United States, an unincor ...
and
limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
– within which was discovered Cambrian age trace ''
trilobite
Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the At ...
'' fossils. Peach and Horne remarked that the fauna are "identical" to those in the corresponding geological strata in North America. 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
Loch Assynt ( gd, Loch Asaint) is a freshwater loch in Sutherland, Scotland, east-north east of Lochinver.
Situated in a spectacular setting between the heights of Canisp, Quinag and Beinn Uidhe, it receives the outflow from Lochs Awe, Maol a ...
. 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
Inchnadamph is a hamlet in Assynt, Sutherland, Scotland. The name is an anglicisation of the Gaelic name Innis nan Damh meaning 'meadow of the stags'. Assynt is a remote area with a low population density. Inchnadamph contains a few houses, a l ...
.
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. 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
The Moine Thrust Belt or Moine Thrust Zone is a linear tectonic feature in the Scottish Highlands which runs from Loch Eriboll on the north coast south-west to the Sleat peninsula on the Isle of Skye. The thrust belt consists of a series of t ...
, moved schist from the east towards and over the pre-existing rock on the west while the effect of
shearing
Sheep shearing is the process by which the woollen fleece of a sheep is cut off. The person who removes the sheep's wool is called a '' shearer''. Typically each adult sheep is shorn once each year (a sheep may be said to have been "shorn" or ...
at the thrust itself was to metamorphose the material at the interface into a
mylonite
Mylonite is a fine-grained, compact metamorphic rock produced by dynamic recrystallization of the constituent minerals resulting in a reduction of the grain size of the rock. Mylonites can have many different mineralogical compositions; it is a cl ...
structure. In "
pipe rock
''Skolithos'' (formerly spelled ''Scolithus'' or ''Skolithus'') is a common trace fossil ichnogenus that is, or was originally, an approximately vertical cylindrical burrow. It is produced by a variety of organisms in shallow marine environment ...
" 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.
The work has been described as "one of the most notable geological memoirs ever published in the English language". 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. 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
Stratigraphy is a branch of geology concerned with the study of rock (geology), rock layers (Stratum, strata) and layering (stratification). It is primarily used in the study of sedimentary rock, sedimentary and layered volcanic rocks.
Stratigrap ...
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.
Afterwards
left, ">Hebridean Terrane
Moine Supergroup and
Moine Thrust Belt
The Moine Thrust Belt or Moine Thrust Zone is a linear tectonic feature in the Scottish Highlands which runs from Loch Eriboll on the north coast south-west to the Sleat peninsula on the Isle of Skye. The thrust belt consists of a series of t ...
The region of the
Moine Thrust
The Moine Thrust Belt or Moine Thrust Zone is a linear tectonic feature in the Scottish Highlands which runs from Loch Eriboll on the north coast south-west to the Sleat peninsula on the Isle of Skye. The thrust belt consists of a series of t ...
is now known to be where part of the
Iapetus Ocean
The Iapetus Ocean (; ) was an ocean that existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale (between 600 and 400 million years ago). The Iapetus Ocean was situated in the southern hemisphere, between the paleoco ...
closed with the collision of the continents of
Laurentia
Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, although ...
and
Baltica
Baltica is a paleocontinent that formed in the Paleoproterozoic and now constitutes northwestern Eurasia, or Europe north of the Trans-European Suture Zone and west of the Ural Mountains.
The thick core of Baltica, the East European Craton, is mo ...
about 400 million years ago. The consequent
Caledonian Orogeny
The Caledonian orogeny was a mountain-building era recorded in the northern parts of the British Isles, the Scandinavian Mountains, Svalbard, eastern Greenland and parts of north-central Europe. The Caledonian orogeny encompasses events that occ ...
produced intense folding and rocks of what is now called the
Moine Supergroup
The Moine Supergroup is a sequence of Neoproterozoic metamorphic rocks that form the dominant outcrop of the Scottish Highlands between the Moine Thrust Belt to the northwest and the Great Glen Fault to the southeast. The sequence is metasediment ...
were thrust a distance of some over the strata at the northwest coast. There is a particularly good exposure of the strata at
Knockan Crag
Knockan Crag ( gd, Creag a' Chnocain, "crag of the small hill")The Story of Knockan Crag National Nature Reserve. p. ii. lies within the North West Highlands Geopark in the Assynt region of Scotland north of Ullapool. During the nineteenth cent ...
, now the site of the Knockan Crag National Nature Reserve, within the
North West Highlands Geopark
The North West Highlands Geopark is a geopark in the Scottish Highlands. Awarded UNESCO geopark status in 2004, it was Scotland's first geopark, featuring some of the oldest rocks in Europe, around 3,000 million years old. The park contains many ...
.
On the centenary of the publication of ''The Geological Structure'', the
Geological Society
The Geological Society of London, known commonly as the Geological Society, is a learned society based in the United Kingdom. It is the oldest national geological society in the world and the largest in Europe with more than 12,000 Fellows.
Fe ...
published an article by Rob Butler discussing the book's continuing significance. 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". Much of the discussion of the geology of the
Lewisian complex
The Lewisian complex or Lewisian gneiss is a suite of Precambrian metamorphic rocks that outcrop in the northwestern part of Scotland, forming part of the Hebridean Terrane and the North Atlantic Craton. These rocks are of Archaean and Paleoprote ...
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.
As well as the 1930 memorial at
Inchnadamph
Inchnadamph is a hamlet in Assynt, Sutherland, Scotland. The name is an anglicisation of the Gaelic name Innis nan Damh meaning 'meadow of the stags'. Assynt is a remote area with a low population density. Inchnadamph contains a few houses, a l ...
, a statue of the two geologists was erected at Knockan Crag in 2001.
See also
*
The Great Devonian Controversy
The Great Devonian Controversy began in 1834 when Roderick Murchison disagreed with Henry De la Beche as to the dating of certain petrified plants found in coals in the Greywacke stratum in North Devon, England. De La Beche was claiming that sinc ...
Notes
References
Citations
Works cited
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** with a brief preemptive paper:
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* (alternative source a
Internet Archive
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Internet Archive
* Oldroyd made some updates to his account at
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Internet Archive.
*. This map is linked to from
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Further reading
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* and subsequent linked pages
{{DEFAULTSORT:Highlands controversy
Geology of Scotland
Geology theories
Geology controversies
History of Earth science
Scientific controversies
19th-century controversies
Geological supergroups
Stratigraphy of Scotland
Geologic formations of Scotland
Rock formations of Scotland
Paleozoic geology
Orogenies of Europe
Plate tectonics
Geological type localities
Terranes
Geology of Highland (council area)
1907 in Scotland
1907 controversies
1907 in paleontology