GCR block - Caledonian igneous (CAL-IGN)

Caledonian igneous

Block Description

UK map showing distribution of GCR sites of GCR block CAL-IGN
Distribution of GCR sites of GCR block Caledonian igneous

The GCR sites selected for this GCR Block represent a major episode of intrusive and extrusive igneous activity in Britain that occurred as a result of the ‘Caledonian Orogeny’, lasting from about 500 million years ago (Ma) to around 360 Ma (see CAL-STR-LD; CAL-STR-SU; CAL-STR-WL), which was a period of mountain building and continental collision that began in the Ordovician Period (which lasted from 495 to 440 Ma) and continued through Silurian (440–417 Ma) and Devonian (417–354 Ma) time.

There is at present no agreed definition of the term ‘Caledonian’, but is taken here to include all of the convergent tectonic and magmatic events arising from the closure of the ‘proto-Atlantic’ Iapetus Ocean in which many of the rocks of Late Proterozoic and early Palaeozoic age had been deposited. It therefore encompasses subduction beneath the continental margins; the accretion or obduction of oceanic crust and island-arc material onto these margins; and ultimate collision of the continents, uplift and development of extensional molasse basins. Within this broad orogenic framework many separate ‘events’ are identified, such as the ‘Grampian Event’ and the ‘Acadian Event’. By this definition, most Caledonian igneous rocks of Britain range in age from about 500 Ma (earliest Ordovician) to around 390 Ma (end Early Devonian), with related activity continuing to around 360 Ma (end Late Devonian) in Orkney and Shetland.

For details of stratigraphy related to the Caledonian Orogeny see GCR Blocks for Ordovician, Silurian and Devonian Stratigraphy: ARE-LLV; ARE-TRE; CAR-ASH; LDO; LDY; LUD; MAR-DEV; NMAR-DEV).

Tectonic setting and evolution

The Iapetus Ocean was created in Late Proterozoic time by the rifting and pulling apart of a large supercontinent known as ‘Rodinia’. The opening started sometime around 650 million years (Ma) ago and, by the beginning of Ordovician time, at 510 Ma, the ocean was at its widest development of possibly up to 5000 km across. On one side of the ocean lay the supercontinent of Laurentia, which is represented today largely by the Precambrian basement rocks of North America, Greenland, the north of Ireland and the Scottish Highlands. On the opposite side lay the supercontinent of Gondwana, consisting of the basements of South America, Africa, India, Australia, East Antarctica and Western Europe (including south Ireland, England and Wales). A separate continent, Baltica (the basement of Scandinavia and Russia), was separated from Gondwana by an arm of the Iapetus Ocean, known as the ‘Tornquist Sea’. The wide separation is supported by palaeontological data which shows distinctly different faunal assemblages in the Lower Palaeozoic rocks of each continent and by palaeomagnetic interpretations.

The continental plates of Laurentia, Gondwana and Baltica started to converge during the early part of the Ordovician Period, initiating new tectonic and magmatic processes which marked the start of the Caledonian Orogeny. The Iapetus oceanic crust was consumed in subduction zones beneath oceanic island arcs and beneath the continental margins.

Magma was being created by the melting of mantle and oceanic crustal material within and above the subduction zones and by melting within the thickened continental crust.

The exact sequence and timing of events as the three plates converged is the subject of much debate, in which the distribution, nature and timing of the igneous activity are crucial evidence.

The tectonic history of the Caledonian Orogeny in Britain can be divided into the following time intervals, linking together coeval magmatic events in the various terranes across the whole orogenic belt.

• Early Ordovician –Tremadoc and Arenig

• Mid-Ordovician –Llanvirn and Llandeilo

• Late Ordovician –Caradoc and Ashgill

• Early and mid-Silurian –Llandovery and Wenlock

• Late Silurian and Early Devonian –Ludlow to Emsian

• Mid- and Late Devonian –Eifelian to Famennian

GCR site selection

Within this GCR Block, sites fall into natural ‘networks’, which are based upon petrological or tectonic affinites, age and geographical distribution. The ten networks are:

• Ordovician Volcanic Rocks and Ophiolites of Scotland

• Ordovician intrusions of the NE Grampian Highlands of Scotland

• Ordovician Igneous rocks of the Lake District

• Ordovician Igneous rocks of Central England

• Ordovician Igneous rocks of Wales

• Silurian and Devonian Plutonic rocks: alkaline ntrusions of the NW highlands of Scotland

• Silurian and Devonian Plutonic rocks: granitic intrusions of Scotland

• Silurian and Devonian Plutonic rocks: northern England

• Silurian and Devonian volcanic rocks: Scotland

• Silurian and Devonian volcanic rocks: Wales

Sites that are important for unravelling the geological history of these major igneous events will also be important for demonstrating general processes of igneous rock petrology, magma evolution and emplacement, and vulcanology (e.g. Cauldron Subsidence theory at Glencoe) irrespective of their role in building up a picture of the sequence of events of geological history of the UK.

Weighting of site selection has focussed on identifying those sites where the contribution of Caledonian igneous rocks of Great Britain to igneous petrology and the understanding of igneous processes and have played a major role in the initiation, testing and evolution of many theories of igneous processes.

Volume Introduction

Caledonian igneous

Site List

Your selection found 56 GCR sites. Sites are sorted alphabetically by country, local authority and then by site name -
CodeNameCountryLocal AuthorityGrid RefGCR Site Account
1409Grainsgill, Caldew ValleyEnglandEast CumbriaNY327328Site Account
3123Langdale PikesEnglandEast CumbriaNY271063Not available
1408Shap Fell CragsEnglandEast CumbriaNY555084Site Account
1410Stockdale Beck, LongsleddaleEnglandEast CumbriaNY492057Site Account
1406Buddon HillEnglandLeicestershire CC and RutlandSK562154Site Account
1405Croft HillEnglandWarwickshireSP510967Site Account
1407Griff HollowEnglandWarwickshireSP361895Site Account
1435Balmedie QuarryScotlandAberdeen City and AberdeenshireNJ944182Site Account
1431Bin QuarryScotlandAberdeen City and AberdeenshireNJ498431Site Account
1437Craig HallScotlandAberdeen City and AberdeenshireNJ530292Site Account
1430Hill of BarraScotlandAberdeen City and AberdeenshireNJ803257Site Account
1434Hill of CreagdeargScotlandAberdeen City and AberdeenshireNJ453259Site Account
1433Hill of JohnstonScotlandAberdeen City and AberdeenshireNJ575250Site Account
1432Pitscurry (Pitmedden) and Legatesden QuarriesScotlandAberdeen City and AberdeenshireNJ737263Not available
2499Red CraigScotlandAngus and Dundee CityNO293758Site Account
1229Allt na CaillicheScotlandCaithness and Sutherland and Ross and CromartyNC320102Site Account
1230Allt nan UamhScotlandCaithness and Sutherland and Ross and CromartyNC256179Site Account
3165An Fharaid MhorScotlandCaithness and Sutherland and Ross and CromartyNC060244Not available
1225Beinn GharbhScotlandCaithness and Sutherland and Ross and CromartyNC222222Site Account
3164Camas Eilean GhlaisScotlandCaithness and Sutherland and Ross and CromartyNB967157Not available
1227Cnoc an DroighinnScotlandCaithness and Sutherland and Ross and CromartyNC263226Site Account
1226Cnoc an Leathaid BhuidheScotlandCaithness and Sutherland and Ross and CromartyNC235154Site Account
1223Creag na h-Innse RuaidheScotlandCaithness and Sutherland and Ross and CromartyNC225135Site Account
1231Glen Oykel NorthScotlandCaithness and Sutherland and Ross and CromartyNC312161Site Account
1222Glen Oykel SouthScotlandCaithness and Sutherland and Ross and CromartyNC327137Site Account
1221Loch Ailsh IntrusionScotlandCaithness and Sutherland and Ross and CromartyNC327130Site Account
1220Loch Borralan IntrusionScotlandCaithness and Sutherland and Ross and CromartyNC289104Site Account
1219Loch Loyal Syenite ComplexScotlandCaithness and Sutherland and Ross and CromartyNC567485Site Account
1228Luban Croma (Leathad Aonghas)ScotlandCaithness and Sutherland and Ross and CromartyNC281135Not available
1224The Laird`s Pool, LochinverScotlandCaithness and Sutherland and Ross and CromartyNC103235Site Account
2078Clatteringshaws Dam QuarryScotlandDumfries and GallowayNX548754Site Account
2446Lea LarksScotlandDumfries and GallowayNX563690Site Account
2507Loch DeeScotlandDumfries and GallowayNX466847Site Account
2502Lotus Quarries to Drungans BurnScotlandDumfries and GallowayNX897685Site Account
2500Millour and Airdrie HillScotlandDumfries and GallowayNX950595Site Account
2165Shoulder o' CraigScotlandDumfries and GallowayNX663491Site Account
2069Garabal Hill to Lochan Strath Dubh-uisgeScotlandEast and West Dumbartonshire, Helensburgh and LomondNN304177Site Account
2445Ardsheal Hill and PeninsulaScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNM963555Site Account
2073Ben Nevis and Allt a` MhuilinnScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNN140757Site Account
1625Bidean nam BianScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNN150546Site Account
2072Bonawe to Cadderlie BurnScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNN008336Site Account
1627Buachaille Etive BeagScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNN201554Site Account
2449Cnoc Mor to Rubh` ArdalanishScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNM367186Site Account
2501Cruachan ReservoirScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNN077285Site Account
2505Glen MoreScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNG861207Site Account
2498KentallenScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNN012579Site Account
2450Knockvologan to Eilean a`ChalmainScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNM309204Site Account
1624Loch AchtriochtanScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNN132557Site Account
2506Loch SunartScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNM776607Site Account
1626Stob Dearg and Cam GhleannScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNN224547Site Account
1623Stob Mhic MhartuinScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNN208576Site Account
2077Craig MoreScotlandPerth and Kinross and StirlingNN787227Site Account
2068Forest LodgeScotlandPerth and Kinross and StirlingNN935744Site Account
2135FuntulichScotlandPerth and Kinross and StirlingNN750265Not available
2131Loch Airighe BhegScotlandPerth and Kinross and StirlingNC703025Site Account
3124Towie WoodScotlandSouth LanarkshireNJ933383Not available
Many designated sites are on private land: the listing of a site in these pages does not imply any right of public access. Search Again