Geology of Scotland 3338124 226131361 2008-07-16T23:22:17Z Jonathan Cardy 4071608 disambig sycamore [[Image:Scotland.central.geological.jpg|thumb|300px|Geological map of Central Scotland]] The '''geology of [[Scotland]]''' is unusually varied for a country of its size, with a large number of differing [[geology|geological]] features.<ref>Keay & Keay (1994) ''op cit'' page 415.</ref> There are three main geographical sub-divisions: the [[Highlands and Islands]] is a diverse area which lies to the north and west of the [[Highland Boundary Fault]]; the [[Central Lowlands]] is a [[rift valley]] mainly comprising [[Paleozoic]] formations; and the [[Southern Uplands]], which lie south of a second fault line, are largely composed of [[Silurian]] deposits. The existing bedrock includes very ancient [[Archean]] [[gneiss]], [[metamorphic rock|metamorphic]] beds interspersed with [[granite]] intrusions created during the Caledonian mountain building period (the [[Caledonian orogeny]]), commercially important [[coal]], [[oil]] and [[iron]] bearing [[carboniferous]] deposits and the remains of substantial [[tertiary]] [[volcano]]es. During their formation, tectonic movements created climatic conditions ranging from polar to desert to tropical and a resultant diversity of [[fossil]] remains. Scotland has also had a role to play in many significant discoveries such as [[plate tectonics]] and the development of theories about the [[petrology|formation of rocks]] and was the home of important figures in the development of the science including [[James Hutton]], (the "father of modern geology")<ref>[http://www.ed.ac.uk/explore/people/plaques/jameshutton.html University of Edinburgh - James Hutton] Retrieved [[16 August]] [[2007]].</ref> [[Hugh Miller]] and [[Archibald Geikie]].<ref name= Keay>Keay & Keay (1994) ''op cit'' pages 415-422.</ref> Various locations such as 'Hutton's Unconformity' at [[Siccar Point]] in Berwickshire and the [[Moine Thrust Belt|Moine Thrust]] in the north west were also important in the development of geological science. [[Image:Asaphiscuswheelerii.jpg|thumb|right|150px|[[Trilobites]] flourished throughout the lower Paleozoic era until becoming extinct in the [[Permian]] period]] ==Overview == [[Image:Scotland (Location) Named (HR).png|thumb|The main geographical divisions of Scotland]] From a [[geology|geological]] and [[geomorphology|geomorphological]] perspective the country has three main sub-divisions all of which were affected by [[Pleistocene]] glaciations. ===Highlands and Islands=== The Highlands and Islands lie to the north and west of the Highland Boundary Fault, which runs from [[Isle of Arran|Arran]] to [[Stonehaven]]. This part of Scotland largely comprises ancient rocks, from the [[Cambrian]] and [[Precambrian]] eras, that were uplifted to form a mountain chain during the later Caledonian [[orogeny]]. These foundations are interspersed with many [[Igneous rock|igneous]] intrusions of a more recent age, the remnants of which have formed mountain massifs such as the [[Cairngorms]] and [[Skye]] [[Cuillins]]. A significant exception to the above are the fossil-bearing beds of [[Old Red Sandstone]]s found principally along the [[Moray Firth]] coast and in the Orkney islands. These rocks are around 400 million years old, and were laid down in the [[Devonian]] period.<ref>McKirdy et al (2007) ''op cit'' pages 124-31.</ref> The [[Scottish Highlands|Highlands]] are generally mountainous and are bisected by the [[Great Glen]] [[Great Glen Fault|Fault]]. The highest elevations in the [[British Isles]] are found here, including [[Ben Nevis]], the highest peak at 1,344 [[metres]] (4,409 [[Foot (unit of length)|ft]]). Scotland has over 790 islands, divided into four main groups: [[Shetland Islands|Shetland]], [[Orkney Islands|Orkney]], and the [[Hebrides]], further sub-divided into the [[Inner Hebrides]] and [[Outer Hebrides]]. [[Image:Stac an Armin and Boreray.jpg|thumb|[[Stac an Armin]], [[St Kilda, Scotland|St Kilda]]]] The Hebridean archipelago outlier of [[St Kilda, Scotland|St Kilda]] is composed of [[Tertiary]] [[igneous]] formations of [[granites]] and gabbro, heavily weathered by the elements. These islands represent the remnants of a long extinct ring volcano rising from a seabed plateau approximately 40&nbsp;m (130&nbsp;ft) below sea level.<ref>[http://www.snh.org.uk/pdfs/trends/seas/Seas_Part1.pdf SNH Trends- seas] (PDF) Retrieved [[02 January]] [[2007]].</ref> The geology of Shetland is complex with numerous faults and fold axes. These islands are the northern outpost of the [[Caledonian orogeny]] and there are outcrops of Lewisian, Dalriadan and Moine metamorphic rocks with similar histories to their equivalents on the Scottish mainland. Similarly, there are also [[Old Red Sandstone]] deposits and [[granite]] intrusions. The most distinctive feature is the ultrabasic [[ophiolites|ophiolite]] [[peridotite]] and [[gabbro]] on [[Unst]] and [[Fetlar]], which are remnants of the [[Iapetus Ocean]] floor.<ref> Gillen, Con (2003) ''op cit''. Pages 90-1.</ref> Much of Shetland's economy depends on the oil-bearing sediments in the surrounding seas.<ref>Keay & Keay (1994) ''op cit'' page 867.</ref> ===Midland Valley=== Often referred to as the [[Central Lowlands]], this is a rift valley mainly comprising [[Paleozoic]] formations. Many of these sediments have economic significance for it is here that the coal and iron bearing rocks that fuelled Scotland's [[industrial revolution]] are to be found. This area has also experienced intense [[volcano|vulcanism]], [[Arthur's Seat, Edinburgh|Arthur’s Seat]] in [[Edinburgh]] being the remnant of a once much larger [[volcano]] active in the [[Carboniferous]] period some 300 million years ago. This area is relatively low-lying, although even here hills such as the [[Ochil Hills|Ochils]] and [[Campsie Fells]] are rarely far from view. ===Southern Uplands=== [[Image:Scotland Southern Uplands01 2002-08-16.jpg|thumb|right|The Southern Uplands]] The [[Southern Uplands]] are a range of hills almost 200&nbsp;km (125&nbsp;miles) long, interspersed with broad valleys. They lie south of a second fault line running from the [[Rhinns of Galloway]] towards [[Dunbar]]. The geological foundations largely comprise [[Silurian]] deposits laid down some 4-500 million years ago.<ref>[http://www.geo.edinburgh.ac.uk/scotgaz/features/featurefirst7744.html "Southern Uplands Fault"] Gazetteer for Scotland. Retrieved [[11 January]] [[2008]].</ref><ref>[http://www.scottishgeology.com/geology/regional_geology/geo_maps/southern_uplands_map.html "Regional Geology, Southern Uplands - Map"] Scottishgeology.com. Retrieved [[21 March]] [[2008]].</ref> ===Post-glacial events=== The whole of Scotland was covered by ice sheets during the [[Pleistocene]] [[ice ages]] and the landscape is much affected by [[glaciation]], and to a lesser extent by subsequent sea level changes.<ref>Murray, W.H. (1973) ''The Islands of Western Scotland''. London. Eyre Methuen.</ref><ref>Murray, W.H. (1977) ''The Companion Guide to the West Highlands of Scotland''. London. Collins.</ref> In the post-glacial epoch, circa 6100 BC, Scotland and the [[Faeroe Islands]] experienced a [[tsunami]] up to 20 metres high caused by the [[Storegga Slide]]s, an immense underwater landslip off the coast of Norway.<ref>[http://www.spiegel.de/international/0,1518,441819,00.html "Study Sees North Sea Tsunami Risk"] Speigel Online. Retrieved [[28 July]] [[2007]].</ref><ref>Bondevik, Stein; Dawson, Sue; Dawson, Alastair; Lohne, Øystein. ([[5 August]] [[2003]]) [http://www.ibg.uit.no/~stein/Bondevik-al-03-EOS.pdf "Record-breaking Height for 8000-Year-Old Tsunami in the North Atlantic"](pdf) EOS, Transactions of the American Geophysical Union. Vol.84 Issue 31, pages 289-293. Retrieved [[15 January]] [[2007]].</ref> Earth tremors are infrequent and usually slight. The Great Glen is the most seismically active area of Britain, but the last event of any size was in 1901.<ref>[http://www.invernessroyal.highland.sch.uk/resources/earthquakes.html#1816 "Earthquakes in the Inverness Area"] Inverness Royal Academy. Retrieved [[8 November]] [[2007]].</ref> ==Chronology== === Archean and Proterozoic eras=== The oldest rocks of Scotland are the [[Lewis]]ian [[gneiss]]es, which were laid down in the [[Precambrian]] period, up to 3,000 [[mya (unit)|million years ago]] ([[mya (unit)|mya]]). They are the oldest in Europe and amongst the oldest rocks in the world. They form basement deposits to the west of the [[Moine Thrust Belt|Moine Thrust]] on the mainland, in the [[Outer Hebrides]] and on the islands of [[Coll]] and [[Tiree]].<ref> Gillen (2003) ''op cit'' page 44.</ref> These rocks are largely igneous in origin, mixed with metamorphosed [[marble]], [[quartzite]] and [[mica schist]] and intruded by later basaltic [[Dyke (geology)|dykes]] and granite magma.<ref>McKirdy et al (2007) ''op cit'' page 95.</ref> One of these intrusions forms the summit plateau of the mountain Roinebhal in [[Harris]]. The granite here is [[anorthosite]], and is similar in composition to rocks found in the mountains of the [[Moon]].<ref> McKirdy et al (2007) ''op cit'' page 94.</ref> [[Image:Suilven looking east.jpg|thumb|[[Suilven]] is formed of [[Torridonian]] [[sandstone]], sitting on a landscape of Lewisian gneiss.]] Torridonian sandstones were also laid down in this period over the gneisses, and these contain the oldest signs of life in Scotland. In later Precambrian times, thick sediments of sandstones, [[limestone]]s muds and [[lava]]s were deposited in what is now the [[Scottish Highlands|Highlands of Scotland]].<ref> McKirdy et al (2007) ''op cit'' page 68.</ref><ref>[http://www.geologyrocks.co.uk/tut.php?tutorial=16 "Precambrian History of the UK"] geologyrocks.co.uk. Retrieved [[01 August]] [[2007]].</ref> ===Paleozoic era=== ====Cambrian period==== Further [[sedimentary]] deposits were formed through the [[Cambrian]] period, (542-488 mya) some of which, along with the earlier Precambrian sediments, [[metamorphic rock|metamorphosed]] into the [[Dalradian]] series. This is composed of a wide variety of materials, including mica schist, [[biotite]] gneiss schist, [[schistose]] grit, [[greywacke]] and [[quartzite]].<ref>Sellar, W.D.H. (ed) (1993) ''Moray: Province and People.'' The Scottish Society for Northern Studies.</ref> The area that would become Scotland was at this time close to the south pole and part of [[Laurentia]]. Fossils from the north-west Highlands indicate the presence of [[trilobite]]s and other primitive forms of life.<ref> McKirdy et al (2007) ''op cit'' page 68.</ref><ref>[http://www.geologyrocks.co.uk/tut.php?tutorial=17 "Palaeozoic History of the UK: Cambrian to Silurian"] geologyrocks.co.uk. Retrieved [[01 August]] [[2007]].</ref> ====Ordovician period==== The proto-Scotland landmass moved northwards and from 460-430 mya [[sandstone]], [[mudstone]] and [[limestone]] was deposited in the area that is now the [[Central Lowlands|Midland Valley]]. This occurred in shallow tropical seas at the margins of the [[Iapetus Ocean]]. The Ballantrae Complex near [[Girvan]] was formed from this ocean floor and is similar in composition to rocks found at [[The Lizard]] in [[Cornwall]]. Nonetheless, northern and southern Britain were far apart at the beginning of this period, although the gap began to close as the continent of [[Avalonia]] broke away from [[Gondwana]], collided with [[Baltica]] and drifted towards Laurentia. The [[Caledonian orogeny]] began forming a mountain chain from [[Norway]] to the [[Appalachians]]. There was an ice age in the southern hemisphere, and the first mass extinction of life on Earth took place at the end of this period.<ref>Gillen (2003) ''op cit'' pages 98 and 111.</ref><ref> McKirdy et al (2007) ''op cit'' page 68.</ref> ====Silurian period==== [[Image:AVALONIA.jpg|thumb|left|300px|The collision of Avalonia, Baltica and Laurentia. <small>(The names are in French).</small>]] During the [[Silurian]] period (443-416 mya) the continent of [[Laurentia]] gradually collided with Baltica, joining Scotland to the area that would become England and Europe. Sea levels rose as the [[Ordovician]] ice sheets melted, and tectonic movements created major faults which assembled the outline of Scotland from previously scattered fragments. These faults are the [[Highland Boundary Fault]], separating the Lowlands from the Highlands, the [[Great Glen Fault]] that divides the North-west Highlands from the Grampians, the Southern Uplands Fault and the [[Iapetus Suture]], which runs from the [[Solway Firth]] to [[Lindisfarne]] and which marks the close of the [[Iapetus Ocean]] and the joining of northern and southern Britain.<ref>Gillen (2003) ''op cit'' pages 69, 73, 75, 88 and 95.</ref><ref> McKirdy et al (2007) ''op cit'' page 68.</ref><ref>[http://www.geologyrocks.co.uk/tut.php?tutorial=17 "Palaeozoic History of the UK: Cambrian to Silurian"] Retrieved [[01 August]] [[2007]].</ref> Silurian rocks form the [[Southern Uplands]] of Scotland, which were pushed up from the sea bed during the collision with Baltica/Avalonia. The majority of the rocks are weakly metamorphosed coarse [[greywacke]].<ref>Gillen (2003) ''op cit'' page 95.</ref> The Highlands were also affected by these collisions, creating a series of [[thrust fault]]s in the northwest Highlands including the [[Moine Thrust Belt|Moine Thrust]], the understanding of which played an important role in nineteenth century geological thinking. [[Volcano|Volcanic activity]] occurred across Scotland as a result of the collision of the [[tectonic plate]]s, with [[volcano]]es in southern Scotland, and [[magma chamber]]s in the north, which today form the [[granite]] mountains such as the [[Cairngorms]].<ref name=Butler>[http://earth.leeds.ac.uk/mtb/ Butler, Rob (2000) ''The Moine Thrust Belt''. Leeds University.] Retrieved [[27 January]] [[2006]].</ref> ====Devonian period==== [[Image:Euramerica en.svg|thumb|300px|The Old Red Sandstone Continent in the Devonian]] The Scottish landmass now formed part of the [[Euramerica|Old Red Sandstone Continent]] and lay some 25 degrees south of the equator, moving slowly north during this period to 10 degrees south. The accumulations of [[Old Red Sandstone]] laid down from 408 to 370 million years ago were created as earlier [[Silurian]] rocks, uplifted by the formation of [[Pangaea]], eroded and were deposited into a body of fresh [[water]] (probably a series of large river deltas). A huge freshwater lake - the [[Orcadian Lakes|Orcadian Lake]] - existed on the edges of the eroding mountains stretching from Shetland to the southern Moray Firth. The formations are extremely thick, up to 11,000 [[metre|meters]] in places, and can be subdivided into three categories "Lower", "Middle", and "Upper" from oldest to youngest. As a result, the Old Red Sandstone is an important source of fish [[fossils]] and it was the object of intense geological studies in the 1800s. In Scotland these rocks are found predominantly in the Moray Firth basin and Orkney Archipelago, and along the southern margins of the Highland Boundary Fault. Elsewhere volcanic activity, possibly as a result of the closing of the Iapetus Suture, created the [[Cheviot Hills]], [[Ochil Hills]], [[Sidlaw Hills]], parts of the [[Pentland Hills]] and Scurdie Ness on the [[Angus]] coast.<ref>[http://www.scottishgeology.com/geology/geological_time_scale/timeline/devonian.htm "The Devonian Period (416 ~ 359 million years ago)"] Scottishgeology.com. Retrieved [[15 August]] [[2007]].</ref><ref>Gillen (2003) ''op cit'' pages 110-119.</ref><ref> McKirdy et al (2007) ''op cit'' pages 124-130.</ref> ====Carboniferous period==== During the [[Carboniferous]] period (359-299 mya), Scotland lay close to the equator. Several changes in sea level occurred and the [[coal]] deposits of [[Lanarkshire]] and [[West Lothian]] and limestones of [[Fife]] and [[Dunbar]] date from this time. There are oil shales near [[Bathgate]] around which the nineteenth century oil-processing industry developed, and elsewhere in the Midland Valley there are ironstones and fire clay deposits that had significance in the early [[Industrial Revolution]]. Fossil Grove in [[Victoria Park, Glasgow]] contains the preserved remains of a Carboniferous forest. More volcanic activity formed [[Arthur's Seat, Edinburgh|Arthur's Seat]] and the [[Salisbury Crags]] in [[Edinburgh]] and the nearby [[Bathgate|Bathgate Hills]].<ref>McKirdy et al (2007) ''op cit'' pages 132-135.</ref><ref>Gillen, Con (2003) ''op cit''. Pages 120-5.</ref> ====Permian period==== [[Image:249 global.gif|right|250px|thumb|Map of Pangaea]] The Old Red Sandstone Continent became a part of the supercontinent [[Pangaea]] in the [[Permian]] (299-251 mya), during which proto-Britain continued to drift northwards. Scotland's climate was arid at this time and some fossils of reptiles have been recovered. However, Permian sandstones are found in only a few places - principally in the south west, on the island of Arran, and on the Moray coast. Stone quarried from [[Hopeman]] in Moray has been used in the [[National Museum of Scotland|National Museum]] and [[Scottish Parliament building]]s in Edinburgh.<ref>McKirdy et al (2007) ''op cit'' pages 141-144.</ref> At the close of this period came the [[Permian–Triassic extinction event]] in which 96% of all [[marine biology|marine]] [[species]] vanished<ref name="Benton">{{cite book|author=Benton M J|date=2005|title=When Life Nearly Died: The Greatest Mass Extinction of All Time|publisher=Thames & Hudson|isbn=978-0500285732}}</ref> and from which bio-diversity took 30 million years to recover. ===Mesozoic era=== ====Triassic period==== During the [[Triassic]], (251-200 mya) much of Scotland remained in desert conditions, with higher ground in the Highlands and Southern Uplands providing sediment to the surrounding basins via flash floods. This is the origin of sandstone outcrops near [[Dumfries]], [[Elgin, Moray|Elgin]] and the [[Isle of Arran]]. Towards the close of this period sea levels began to rise and climatic conditions became less arid.<ref>[http://www.scottishgeology.com/geology/geological_time_scale/timeline/permian.htm "The Permian & Triassic Periods (299 ~251 and 251 ~ 200 million years ago respectively)"] Scottishgeology.com. Retrieved [[31 July]] [[2007]].</ref> ====Jurassic period==== [[Image:Laurasia-Gondwana.png|thumb|right|250px|[[Pangaea]] was formed by the convergence of multiple continental masses and later broke apart to form two primary continents, [[Laurasia]] and Gondwana]] As the [[Jurassic]] (200-145 mya) started, [[Pangaea]] began to break up into two [[continents]], [[Gondwana]] and [[Laurasia]], marking the beginning of the separation of Scotland and North America. Sea levels rose, as Britain and Ireland drifted on the [[Eurasian Plate]] to between 30° and 40° north. Most of northern and eastern Scotland including Orkney, Shetland and the Outer Hebrides remained above the advancing seas, but the south and south-west were inundated. There are only isolated [[sedimentary rock]]s remaining on land from this period, on the [[Sutherland]] coast near Golspie and on Skye, Mull, [[Raasay]] and [[Eigg]]. This period does however have considerable significance. The burial of [[algae]] and [[bacterium|bacteria]] below the mud of the sea floor during this time resulted in the formation of [[North Sea oil]] and [[natural gas]], much of it trapped in overlying sandstone by deposits formed as the seas fell to form the swamps and salty lakes and lagoons that were home to [[dinosaur]]s.<ref>McKirdy et al (2007) ''op cit'' page 146.</ref><ref> Gillen, Con (2003) ''op cit'' Pages 133-7.</ref> ====Cretaceous period==== In the [[Cretaceous]], (146-65 mya) Laurasia split into the continents of [[North America]] and [[Eurasia]]. Sea levels rose globally during this period and much of low-lying Scotland was covered in a layer of [[chalk]]. Although large deposits of [[Cretaceous]] rocks were laid down over Scotland, these have not survived erosion except in a few places on the west coast such as [[Loch Aline]] in [[Morvern]].<ref>Gillen (2003) ''op cit'' pages 138-9.</ref><ref>[http://www.scottishgeology.com/geology/geological_time_scale/timeline/cretaceous.htm "The Cretaceous Period (146 ~ 65 million years ago)"] Scottish geology.com. Retrieved [[16 August]] [[2007]].</ref> At the end of this period the [[Cretaceous–Tertiary extinction event]] brought the age of dinosaurs to a close. ===Cenozoic era=== ====Paleogene period==== In the early [[Paleogene]] period between 63 and 52 mya, the last volcanic rocks in the British Isles were formed. As [[North America]] and [[Greenland]], separated from Europe the [[Atlantic Ocean]] slowly formed. This led to a chain of volcanic sites west of mainland Scotland including on [[Isle of Skye|Skye]], the [[Small Isles]] and [[St Kilda, Scotland|St. Kilda]], in the [[Firth of Clyde]] on [[Isle of Arran|Arran]] and [[Ailsa Craig]] and at [[Ardnamurchan]].<ref>Gillen (2003) ''op cit'' page 142.</ref> Sea levels began to fall, and for the first time the general outline of the modern British Isles was revealed.<ref> McKirdy et al (2007) ''op cit'' page 150.</ref> At the beginning of this period the climate was sub-tropical and erosion was caused by chemical weathering, creating characteristic features of the Scottish landscape such as the topographical basin of the Howe of [[Alford, Aberdeenshire|Alford]] near Aberdeen.<ref> McKirdy et al (2007) ''op cit'' page 158.</ref> By 35 mya the landscape included [[beech]], [[oak]], [[chestnut]] and [[Sycamore Maple|sycamore]] trees, along with [[grass]]land. ====Neogene period==== =====Miocene and Pliocene epochs===== In the [[Miocene]] and [[Pliocene]] epochs further uplift and erosion occurred in the Highlands. Plant and animal types developed into their modern forms, and by about 2 million years ago the landscape would have been broadly recognisable today, with Scotland lying in its present position on the globe. As the Miocene progressed, temperatures dropped and remained similar to today's.<ref> McKirdy et al (2007) ''op cit'' page 158.</ref><ref>[http://www.fettes.com/Cairngorms/tertiary.htm "Tertiary"] Fettes.com Retrieved [[16 August]] [[2007]].</ref> =====Pleistocene epoch===== [[Image:Barns of Bynack.jpg|thumb|The 'Barns of Bynack' - tors on the summit plateau of [[Bynack More]], [[Cairngorm National Park]].]] Several [[ice age]]s shaped the land through glacial erosion, creating [[Glaciated valley|u-shaped valleys]] and depositing [[boulder clay]]s, especially on the western seaboard. The last major incursion of ice peaked about 18,000 years ago, leaving other remnant features such at the granite [[tor]]s on the [[Cairngorms|Cairngorm Mountain]] plateaux.<ref> McKirdy et al (2007) ''op cit'' pages 159 and 163-171.</ref><ref>[http://www.scottishgeology.com/geology/geological_time_scale/timeline/quaternary.htm "The Quaternary"] Scottishgeology.com. Retrieved [[16 August]] [[2007]].</ref> =====Holocene epoch===== Over the last twelve thousand years the most significant new geological features have been the deposits of [[peat]] and the development of coastal alluvium. Post-glacial rises in sea level have been combined with [[isostasy|isostatic]] rises of the land resulting in a relative fall in sea level in most areas.<ref>[http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=87 "Update to UKCIP02 sea level change estimates"] (December 2005) UK Climate Impacts Programme. Retrieved [[10 June]] [[2008]].</ref><ref> Smith, David E., and Fretwell, Peter T. [http://www.scottishsealevels.net/scottish-sea-level-change.htm "Scottish Sea Levels"] scottishsealevels.net. Retrieved [[15 November]] [[2007]].</ref> In some places, such as Culbin in Moray, these changes in relative sea level have created a complex series of shorelines.<ref>Ross, Sinclair (1992) ''The Culbin Sands – Fact and Fiction''. Aberdeen University Press.</ref> About half of the [[coastline]] of Scotland consists of [[Machair (geography)|machair]] [[habitat]],<ref>{{cite web|url=http://www.wildlifehebrides.com/environment/machair/| publisher = wildlifehebrides.com | title="The Natural Environment: Machair" | accessdate = 2007-10-03}}</ref> a low lying dune pasture land formed as the sea level dropped leaving a raised beach. In the present day, Scotland continues to move slowly north. == Geologists in Scotland== [[Image:James Hutton.jpg|thumb|James Hutton, painted by Abner Lowe]] Scottish geologists and non-Scots working in Scotland have played an important part in the development of the science, especially during its pioneering period in the late eighteenth and nineteenth centuries.<ref>Keay & Keay (1994) ''op cit'' page 415.</ref> *[[James Hutton]] (1726-1797) the "father of modern geology" was born in Edinburgh. His ''Theory of the Earth'', published in 1788 proposed the idea of a rock cycle in which weathered rocks form new sediments and that granites were of volcanic origin. At [[Glen Tilt]] in the [[Cairngorms|Cairngorm]] mountains he found [[granite]] penetrating [[metamorphic rock|metamorphic]] [[schist]]s. This showed to him that granite formed from the cooling of molten rock, not [[Precipitation (chemistry)|precipitation]] out of water as the [[Neptunism|Neptunists]] of the time believed.<ref name="Macfarlane">{{cite web |url= http://findarticles.com/p/articles/mi_qa3724/is_200309/ai_n9253355 |title= Glimpses into the abyss of time |author= Robert Macfarlane |format= [[html]] |work= [[The Spectator]] |publisher= Review of Repcheck's ''The Man Who Found Time'' |date= [[13 September]] [[2003]]}}</ref> This sight is said to have "filled him with delight".<ref>Keay & Keay (1994) ''op cit'' page 531.</ref> Regarding geological time scales he famously remarked "that we find no vestige of a beginning, no prospect of an end."<ref>McKirdy et al (2007) ''op cit'' pages 61 and 115.</ref> *[[John Playfair]] (1748-1819) from [[Angus]] was a mathematician who developed an interest in geology through his friendship with Hutton. His 1802 ''Illustrations of the Huttonian Theory of the Earth'' were influential in the latter's success.<ref>''Biographical Dictionary of Eminent Scotsmen'' (1856), reproduced in [http://www.electricscotland.com/history/other/playfair_john.htm "Significant Scots"] electricscotland.com. Retrieved [[03 October]] [[2007]].</ref> *[[John MacCulloch]] (1773-1835) was born in [[Guernsey]] and like Hutton before him, studied medicine at [[Edinburgh University]]. A president of the Geological Society from 1815-17, he is best remembered for producing the first geological map of Scotland, published in 1836. '[[Macculloch's Tree]]', a 40&nbsp;foot high fossil conifer in the Mull lava flows, is named after him.<ref>McKirdy et al (2007) ''op cit'' page 156.</ref><ref >Jones (1997) ''op cit''. Page 38.</ref> [[Image:Charles Lyell.jpg|thumb|Charles Lyell]] *[[Charles Lyell|Sir Charles Lyell]] (1797-1875) was also from Angus and his ''[[Principles of Geology]]'' built on Hutton's ideas. Lyell's theory of [[Uniformitarianism (science)|uniformitarianism]] and his interpretation of geologic change as the steady accumulation of minute changes over enormously long spans of time was a central theme in the ''Principles'', and a powerful influence on the young [[Charles Darwin]]. ([[Robert FitzRoy]], captain of [[HMS Beagle|HMS ''Beagle'']], loaned Darwin a copy of Volume 1 of the first edition just before they set out on the [[Second voyage of HMS Beagle|'Voyage of the Beagle']].) Lyell is buried in [[Westminster Abbey]].<ref>Keay & Keay (1994) ''op cit'' page 641.</ref><ref>[http://www.british-history.ac.uk/report.asp?compid=45165 "Westminster Abbey.—A Survey of the Building."] British History Online. Retrieved 12 August 2007</ref><ref>[http://www.aboutdarwin.com/people/people_01.html#0145 "Lyell, Sir Charles [1797 - 1875]" About Darwin.com. Retrieved [[12 August]] [[2007]].</ref> [[Image:Memorial tablet of Roderick Murchison at the School 9 in Perm.jpg|thumb|Murchison's memorial tablet in [[Perm]]. "To Roderick Impey Murchison, Scottish geologist, explorer of Perm Krai, who gives to the last period of Paleozoic era the name of Perm."]] * [[Roderick Murchison|Sir Roderick Murchison]] (1792–1871) was born in Ross and Cromarty and served under [[Arthur Wellesley, 1st Duke of Wellington| Wellesley]] in the [[Peninsular War]]. Knighted in 1846, his main achievements were the investigation of [[Silurian]] rocks published as ''The Silurian System'' in 1839 and of [[Permian]] deposits in [[Russia]]. The [[Murchison (crater)|Murchison crater]] on the [[Moon]] and at least fifteen geographical locations on Earth are named after him.<ref>Morton, John L. (2004) ''King of Siluria &mdash; How Roderick Murchison Changed the Face of Geology''. Horsham. Brocken Spectre. ISBN 0954682904.</ref><ref>Keay & Keay (1994) ''op cit'' page 717.</ref> * [[Hugh Miller]] (1802-56) from [[Cromarty]] was a stonemason and self-taught geologist. His 1841 publication ''The Old Red Sandstone'' became a bestseller. The fossils founds in these rocks were one of his fascinations, although his deep religious convictions led him to oppose the idea of biological [[theories of evolution|evolution]].<ref>[http://www.hughmiller.org/who_was_hugh_g.asp "Who Was He, Then?"] Discover Hugh Miller. Retrieved [[08 July]] [[2007]].</ref> *[[James Croll]] (1821-90) developed a theory of [[climate]] change based on changes in the earth's [[planetary orbit|orbit]]. Born near [[Perth, Scotland|Perth]], he was self-educated and his interest in science led to his becoming appointed as a janitor in the museum at the [[Andersonian College and Museum]], Glasgow in 1859. His 1864 paper ''On the Physical Cause of the Changes of Climate during Glacial Epochs'' led to a position in the [[Edinburgh]] office of the [[British Geological Survey|Geological Survey of Scotland]], as keeper of maps and correspondence, where Sir [[Archibald Geikie]], encouraged his research. He was eventually to become a Fellow of the [[Royal Society]].<ref>McKirdy et al (2007) ''op cit'' page 77.</ref> *[[Archibald Geikie|Sir Archibald Geikie]] (1835-1924) was the first to recognise that there had been multiple glaciations, and his 1863 paper ''On the glacial drift of Scotland'' was a landmark in the emergent theories of [[glaciation]]. He became Director-General of the Geological Survey of the United Kingdom in 1888 and was also well-known for his work on [[vulcanism]].<ref>McKirdy et al (2007) ''op cit'' page 86.</ref> *[[Arthur Holmes]] (1890-1965) was born in England and became Regius Professor of Geology at the [[University of Edinburgh]] in 1943. His ''magnum opus'' was ''Principles of Physical Geology'', first published in 1944, in which he proposed the idea that slow moving convention currents in the Earth's mantle created 'continental drift' as it was then called. He also pioneered the discipline of [[geochronology]]. He lived long enough to see the theory of [[plate tectonics]] become widely accepted, and he is regarded as one of the most influential geologists of the 20th century.<ref> McKirdy et al (2007) ''op cit'' page 54.</ref> ==Important sites== [[Image:Siccar Point.jpg|thumb|250px|'[[Hutton's Unconformity]]' at [[Siccar Point]]]] * [[Siccar Point]], [[Berwickshire]] is world famous as one of the sites that proved Hutton's views about the immense age of the Earth. Here Silurian rocks have been tilted almost to the vertical. Younger Devonian rocks lie [[unconformity|unconformably]] over the top of them, dipping gently, indicating that an enormous span of time must have passed between the creation of the two beds. When Hutton and [[James Hall, 4th Baronet|James Hall]] visited the site in 1788 their companion Playfair wrote:<ref>McKirdy et al (2007) ''op cit'' page 253.</ref><ref>Gillen (2003) ''op cit'' page 95.</ref> {{Quote box |width=60% |align=centre |quote=On us who saw these phenomenon for the first time the impression will not easily be forgotten...We felt necessarily carried back to a time when the schistus on which we stood was yet at the bottom of the sea, and when the sandstone before us was only beginning to be deposited, in the shape of sand or mud, from the waters of the supercontinent ocean... The mind seemed to grow giddy by looking so far back into the abyss of time; and whilst we listened with earnestness and admiration to the philosopher who was now unfolding to us the order and series of these wonderful events, we became sensible how much further reason may sometimes go than imagination may venture to follow.|source=[[John Playfair]] (1805) Transactions of the [[Royal Society of Edinburgh]], vol. V, pt. III.<ref>{{cite web |url= http://findarticles.com/p/articles/mi_m1134/is_5_108/ai_54830705 |title= Hutton's Unconformity |author= [[John Playfair]] |format= [[html]] |work= Transactions of the [[Royal Society of Edinburgh]], vol. V, pt. III, [[1805]], quoted in [[Natural History (magazine)|Natural History]], June 1999}}</ref> }} * The [[Moine Thrust Belt|Moine Thrust]] in [[Assynt]] is one of the most studied geological features in the world. Its discovery in the 1880s was a milestone in the history of geology as it was one of the first thrust belts in the world to be identified.<ref name=Butler/> Investigations by [[John Horne]] and [[Ben Peach|Benjamin Peach]] resolved a dispute between Murchison and Geikie on the one hand and James Nicol and [[Charles Lapworth]] on the other. The latter believed that older Moine rocks lay on top of younger Cambrian rocks at [[Knockan Crag]], and Horne and Peach's work confirmed this in their classic paper ''The Geological Structure of the Northwest Highlands of Scotland'', which was published in 1907.<ref>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.</ref><ref>Peach, B.N., Horne, J., Gunn, W., Clough, C.T., and Hinxman, L.W., (1907) ''The Geological Structure of the Northwest Highlands of Scotland''. Memoirs of the Geological Survey of Great Britain.</ref> A statue to these two pioneers of fieldwork was erected at [[Inchnadamph]] near the hotel there which played a prominent part in the annals of early geology.<ref>McKirdy et al (2007) ''op cit'' pages 110 and 121-122.</ref> This area is at the heart of the 'North West Highlands Geopark'.<ref>[http://www.northwest-highlands-geopark.org.uk/ "Welcome to North West Highland Geopark] northwest-highlands-geopark.org.uk. Retrieved [[18 August]] [[2007]].</ref> * Lapworth also had a prominent role to play in the fame of [[Dob's Linn]], a small gorge in the [[Scottish Borders]], which contains the 'golden spike' (i.e. the official international boundary or stratotype) between the Ordovician and Silurian periods. Lapworth's work in this area, especially his examination of the complex [[stratigraphy]] of the Silurian rocks by comparing fossil [[graptolite]]s, was crucial in to the early understanding of these epochs. [[Image:Pinnacle ridge&gillean2.jpg|thumb|[[Sgurr nan Gillean]] and the Pinnacle Ridge from Basteir gorge, [[Skye]]. James Forbes and Duncan MacIntyre completed the first recorded climb of this mountain in 1836.<ref>McKirdy et al (2007) ''op cit'' page 88.</ref>]] * The Skye [[Cuillin]] mountains provide classic examples of glacial topography and were the subject of an early published account by [[James David Forbes|James Forbes]] in 1846 (who had become a fellow of the [[Royal Society of Edinburgh]] aged only nineteen).<ref>{{cite web|url=http://www.1911encyclopedia.org/James_David_Forbes| title = "James David Forbes" | publisher=1911encyclopedia.org | accessdate = 2007-10-03}}</ref><ref>Forbes, James D. (1846) ''Notes on the topography and geology of Cuchullin Hills in Skye, and on traces of ancient glaciers which they present''. Edinburgh New Philosophical Journal No. 40. Pages 76-99.</ref> He partnered [[Louis Agassiz]] on his trip to Scotland in 1840 and although they subsequently argued, Forbes went on to publish other important papers on Alpine glaciers.<ref>Forbes, James D. (1846) ''On the Viscous Theory of Glacier Motion'' Abstracts of the Papers Communicated to the Royal Society of London, Vol. 5, 1843 - 1850. Pages 595-596.</ref> * In 1904 [[Alfred Harker]] published ''The Tertiary Igneous Rocks of Skye'', the first detailed scientific study of an extinct volcano.<ref>McKirdy et al (2007) ''op cit'' pages 164-5 and 280.</ref><ref>Harker, Alfred, (1904) ''The Tertiary Igneous Rocks of Skye''. Geological Survey of Scotland Memoir.</ref> * In the hills to the north of the village of [[Strontian]] the mineral [[strontianite]] was discovered, from which the element [[strontium]] was first isolated by Sir [[Humphry Davy]] in 1808.<ref>[http://www.undiscoveredscotland.co.uk/strontian/strontian/ "Strontian"] Undiscovered Scotland. Retrieved [[08 July]] [[2007]].</ref><ref>[http://www.rock-site.co.uk/Pages/Strontian/Strontian.html "History and Minerals of Strontian mines"] rock-site.co.uk. Retrieved [[08 July]] [[2007]].</ref> * The island of [[Staffa]], contains [[Fingal's Cave]] made up of massive rectangular columns of [[Tertiary]] basalt and Mackinnon's Cave, one of the longest sea caves in the world.<ref>[http://www.caverbob.com/seacave.html "Long Sea Caves of the World"] caverbob.com. Retrieved [[14 April]] [[2007]]. Note however that the list only features entries from North America, Hawaii, and Europe.</ref> * The [[Munro]] [[Schiehallion]]'s isolated position and regular shape led [[Nevil Maskelyne]] to use the deflection caused by the [[mass]] of the mountain to estimate the mass of the [[Earth]] in a ground-breaking experiment carried out in 1774. Following Maskelyne's survey, Schiehallion became the first mountain to be mapped using [[contour line]]s.<ref>[http://adsabs.harvard.edu/full/1985QJRAS..26..289D Davies, R.D. (1985) ''A Commemoration of Maskelyne at Schiehallion''. Royal Astronomical Society Quarterly Journal. Vol. 26 No.3] Retrieved [[08 July]] [[2007]].</ref> * The village of [[Rhynie]] in [[Aberdeenshire]] is the site of an important sedimentary deposit - [[Rhynie chert]]. The bulk of this fossil bed consists of primitive [[plant]]s that had [[xylem|water-conducting cells]] and [[spores|sporangia]] but no [[leaf|leaves]], along with [[arthropod]]s: [[Collembola]], [[Opiliones]] ([[harvestman|harvestmen]]), [[pseudoscorpion]]s and the extinct, spider-like [[Trigonotarbid]]s. This fossil bed is remarkable for two reasons. Firstly, the age of the find ([[Devonian|early Devonian]] circa 410 mya)<ref>Rice, C. M., Ashcroft, W. A., Batten, D. J., Boyce, A. J., Caulfield, J. B. D., Fallick, A. E., Hole, M. J., Jones, E., Pearson, M. J., Rogers, G., Saxton, J. M., Stuart, F. M., Trewin, N. H. & Turner, G. (1995) ''A Devonian auriferous hot spring system, Rhynie, Scotland''. Journal of the Geological Society, London, 152. Pages 229-250.</ref><ref>[http://www.bgs.ac.uk/nigl/pdf_downloads/2004AnnualReport.pdf "Absolute age and underlying cause of hot-spring activity at Rhynie, NE Scotland from high precision geo-chronology"] (pdf) ''NIGL Annual Report for 2003-4''. Annex 7: Scientific highlights for the 2003-2004 year. p. 42.</ref> makes this one of the earliest sites anywhere containing terrestrial fossils, coinciding with the first stages of the colonisation of land by plants and [[animal]]s. Secondly, these [[chert]]s are famous for their exceptional state of [[ultrastructure|ultrastructural]] preservation, with individual cell walls easily visible in polished specimens. For example, [[stomata]] have been counted and [[lignin]] remnants detected in the plant material. * A disused quarry at [[East Kirkton]] in the [[Bathgate|Bathgate Hills]] is the location where the Carboniferous fossil of ''[[Westlothiana|Westlothiana lizziae]]'' (aka 'Lizzie') was found in 1984. This lizard is one of the earliest known ancestors of the [[reptile]]s. The specimen was purchased in part by public subscription and is now on display in the [[National Museum of Scotland]]. The site was originally discovered in the early nineteenth century and has also provided fossil [[eurypterid]]s, [[shark]]s and a variety of primitive [[acanthodian]] fish.<ref>McKirdy et al (2007) ''op cit'' page 132.</ref> * In 2008 the ejected material from a [[meteorite]] impact crater was discovered near [[Ullapool bolide impact|Ullapool]] in Wester Ross. Preserved within sedimentary layers of sandstone, this is the largest known [[bolide]] impact from what are now the [[British Isles]].<ref> Amor, Kenneth; Hesselbo, Stephen P.; Porcelli, Don; Thackrey, Scott; and Parnell, John (April 2008) [http://www.gsajournals.org/perlserv/?request=get-document&doi=10.1130%2FG24454A.1 "A Precambrian proximal ejecta blanket from Scotland"] ''Geological Society of America''. Volume 36:4 pp. 303–306.</ref> [[Category:Astroblemes]] ==See also== * [[Geography of Scotland]] * * * [[Geology of the British Isles]] :* [[Geology of Ireland]] :* [[Geology of England]] :* [[Geology of Wales]] *[[British Geological Survey]] *[[Geologic timescale]] *[[Coal Measures]] *[[Old Red Sandstone]] *[[New Red Sandstone]] ==References== General references: * Gillen, Con (2003) ''Geology and landscapes of Scotland''. Harpenden. Terra Publishing. * Jones, Rosalind (1997) ''Mull in the Making''. Aros. R Jones. ISBN 0953189007 * Keay, J. & Keay, J. (1994) ''Collins Encyclopaedia of Scotland''. London. HarperCollins. * McKirdy, Alan Gordon, John & Crofts, Roger (2007) ''Land of Mountain and Flood: The Geology and Landforms of Scotland''. Edinburgh. Birlinn. *[http://www.scottishgeology.com "Scottish Geology"] Scottishgeology.com. Retrieved [[30 September]] [[2007]]. ==Footnotes == {{reflist|2}} == External links == * [http://www.scottishgeology.com Scottish Geology.com] {{Scotland topics}} {{Geology of Europe}} [[Category:Scottish geologists]] [[Category:Scottish paleontologists]] [[Category:Geology of Scotland|Geology of Scotland]] [[Category:Geology by country|Scotland]] [[no:Skottlands geologi]]