Knockan Crag National Nature Reserve
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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 century Knockan Crag became the subject of much debate when geologists noted that the Moine schists at the top of the crag appeared to be older than the
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 ...
and Ordovician rocks such as
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 ...
limestone lower down. Disagreements over the processes that could have caused this to occur were referred to at the time as the "
Highlands Controversy 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 contentio ...
". The argument was primarily between
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 ...
and Archibald Geikie on the one hand and James Nicol and Charles Lapworth on the other. Murchison and Geikie believed the sequence was wrong and that the Moine schists must be the younger rocks. The controversy was finally resolved by the work of Ben Peach and John Horne whose 1907 paper on the subject remains a classic text. Peach and Horne demonstrated that the situation resulted from the action of a thrust fault - this being the first to be discovered anywhere in the world. The older rocks had been moved some 70 kilometres to the west over the top of the younger rocks due to tectonic action.The Story of Knockan Crag National Nature Reserve. p. 4. The crag is designated as a national nature reserve (NNR) due to its geological features, and is owned and managed by NatureScot.The Story of Knockan Crag National Nature Reserve. p. 2. There is a car park and interpretation centre that explains the geology of the area and gives background to the Highlands Controversy, along with three waymarked trails that take visitors to points of interest across the site. The site also hosts artworks such as 'The Globe' by Joe Smith and 'Pipeworm’ by Susheila Jamieson that were commissioned to highlight the inspiration that the landscape has had on artists and poets.The Story of Knockan Crag National Nature Reserve. p. 12.


Geological significance

The presence of metamorphic gneisses and schists lying apparently stratigraphically above sedimentary rocks of lower Paleozoic age in the Northwest Highlands had been known since the early nineteenth century, convincing
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 ...
that the change was a purely metamorphic effect and that the upper gneiss was younger than the sediments beneath. Initially he was supported in this interpretation by Geikie, and
James Nicol James Nicol, Nichol, Nicholl or Nicoll may refer to: * James Nicol (geologist) (1810–1879), Scottish geologist * James Nicol (minister) (1769–1819), Scottish poet * James Dyce Nicol (1805–1872), Scottish politician * James Nicholl (1890–1 ...
. After further fieldwork, Nicol changed his mind and advocated instead that the contact at the base of the upper gneisses was tectonic, starting what was known as the
Highlands Controversy 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 contentio ...
. A tectonic interpretation was supported by, amongst others, Charles Lapworth who had corresponded with
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 ...
on similar structures in the Alps. In 1883 and 1884 the
British Geological Survey The British Geological Survey (BGS) is a partly publicly funded body which aims to advance geoscientific knowledge of the United Kingdom landmass and its continental shelf by means of systematic surveying, monitoring and research. The BGS h ...
geologists Ben Peach and John Horne were sent into the area by the survey's director Archibald Geikie to carry out detailed mapping. The results of the mapping proved conclusively to Peach and Horne that the contact was tectonic and they were eventually able to persuade Geikie when he visited them briefly in the field in October 1884. In November that year Peach and Horne's preliminary results were published and Geikie published a paper in the same issue of Nature in which he coined the term "thrust-plane" for these low-angle faults, although the term was probably already in use before then. By 1888 the term "Moine Thrust" was being used for the tectonic break at the base of Moine schists (what is now called the Moine Supergroup). The recognition of the Moine Thrust Belt in the early 1880s was a milestone in the history of geology as it was one of the first thrust belts discovered and where the importance of large scale horizontal rather than vertical movements became apparent. Detailed mapping of the Moine Thrust Belt by the survey continued for another two decades, culminating in the classic survey memoir '' The Geological Structure of the North-West Highlands of Scotland'', published in 1907.Peach, B.N., Horne, J., Gunn, W., Clough, C.T., Hinxman, L.W., and Cadell, H.M. (1888) ''Report on the recent work of the Geological Survey in the north-west Highlands of Scotland, based on field notes and maps by Messrs. B.N. Peach, J. Horne, W. Gunn, C.T. Clough, L.W. Hinxman, L.W. and H.M. Cadell''. Quarterly Journal of the Geological Society of London, 44, 378-441. A monument to Peach and Horne's work was erected by the international geological community 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 few miles to the north.


Flora and fauna

The plant life of the area is highly influenced by its underlying geology. The soils formed on areas of limestone, fucoid beds and salterella grits are much richer than those on Moine schists. The lime-rich areas consequently support a richer vegetation, including plants such as
mountain avens ''Dryas octopetala'', the mountain avens, eightpetal mountain-avens, white dryas or white dryad, is an Arctic–alpine flowering plant in the family Rosaceae. It is a small prostrate evergreen subshrub forming large colonies. The specific epit ...
and rock sedge, whilst areas underlain by Moine schists tend to consist of wet heath and blanket bog. The transition between the two vegetation patterns is especially marked on the plateau above the crags, where there are small limestone knolls separated by peat-filled areas.The Story of Knockan Crag National Nature Reserve. p.p. 8-9. Bird species found at Knockan Crag include kestrel,
raven A raven is any of several larger-bodied bird species of the genus ''Corvus''. These species do not form a single taxonomic group within the genus. There is no consistent distinction between "crows" and "ravens", common names which are assigned t ...
and ring ouzel, along with song birds such as dunnock,
wren Wrens are a family of brown passerine birds in the predominantly New World family Troglodytidae. The family includes 88 species divided into 19 genera. Only the Eurasian wren occurs in the Old World, where, in Anglophone regions, it is commonly ...
,
stonechat ''Saxicola'' (Latin: ''saxum'', rock + ''incola'', dwelling in.), the stonechats or chats, is a genus of 15 species of small passerine birds restricted to the Old World. They are insectivores occurring in open scrubland and grassland with scatte ...
and meadow pipit. Red- and black-throated divers visit nearby Lochan an Ais during the winter and spring, and so can be observed from the crag. Red deer regularly cross through the site.


Conservation designations

Knockan Crag became part of the
Inverpolly Inverpolly is the name given to a large area of northern Wester Ross in the Northwest Highlands of Scotland, north of Ullapool. The area contains several prominent hills, rising up from a rough landscape of bogs and lochans. From 1961, the area ...
national nature reserve (NNR) on 28 September 1962. In 2004, following a review of all NNRs in Scotland, it was decided to remove NNR status from the wider Inverpolly area, however it was to be retained for Knockan Crag.The Story of Knockan Crag National Nature Reserve. p. 11. The crag was declared a NNR in its own right on 24 February 2004. The NNR is part of the wider Knockan Cliffs
Site of Special Scientific Interest A Site of Special Scientific Interest (SSSI) in Great Britain or an Area of Special Scientific Interest (ASSI) in the Isle of Man and Northern Ireland is a conservation designation denoting a protected area in the United Kingdom and Isle of ...
, and is classified as a Category III
protected area Protected areas or conservation areas are locations which receive protection because of their recognized natural, ecological or cultural values. There are several kinds of protected areas, which vary by level of protection depending on the ena ...
by the International Union for Conservation of Nature. It also lies within the North West Highlands Geopark, part of the International Network of Geoparks.North West Highlands Geopark
North West Highlands Geopark. Retrieved 18 August 2007.


See also

* Geology of Scotland


References


Citations


Further reading

* The full text of the Third Edition of this publication (Phemister, 1960) can be found at *


External links


Knockan Crag National Nature Reserve
- official site
Scotland's National Nature Reserves
{{National Nature Reserves of Scotland Landforms of Sutherland Geology of Highland (council area) Protected areas of Highland (council area) National nature reserves in Scotland Landforms of Highland (council area) Cliffs of Scotland