GCR block - Variscan Structures of South-West England (VAR-STR-SW)

Variscan Structures of South-West England

Block Description

UK map showing distribution of GCR sites of GCR block VAR-STR-SW
Distribution of GCR sites of GCR block Variscan Structures of South-West England

The GCR sites selected for this GCR Block represent a major episode of Earth history that occurred as a result of the ‘Variscan Orogeny’, which was a period of mountain building and continental collision that began in the Devonian Period, which lasted from 417 to 354 million years ago (Ma) and continued through Carboniferous (354–292 Ma) time, as represented by geological features present in south-west England; geological structures of south Wales and the Mendips produced by the same events are covered by a separate GCR, for both geographical and geological reasons (see VAR-STR-WM).

The Variscan Orogeny occurred as a result of the northward convergence and collision of the continent of Gondwana (comprising South America, Africa, India, Australia and Antarctica) with the southern margin of the stable continent of Laurasia (comprising North America, Europe and Asia). On collision, the supercontinent Pangaea was formed, being a single, huge landmass in the ocean Panthalassa. The Variscan Orogeny resulted in the formation of a mountain belt that included the Appalachians of eastern North America. The main orogenic belt associated with this collision was located far to the south of Great Britain in the Iberia–Armorica–Massif Central region. However, the northern limit of strong Variscan deformation, commonly known as the ‘Variscan Front’, migrated northwards during the orogeny and the final limit extends across southern Britain, between the Thames and Severn estuaries. To the north of this orogenic front, back-arc extension controlled structure, sedimentation and igneous activity in the British Isles throughout Late Devonian and Carboniferous times (see C-P-IG.).

Cornwall, or the Cornubian Massif, represents part of a trough into which sediments, eroded from the forming mountains, were accumulated. This trough, called the ‘North Variscan Foredeep’ would once have extended along the whole of the strike of the belt from Poland to western Ireland. Only small fragments are now exposed.

During the final stages of continental collision, the sediments were folded and a large granite batholith was intruded into this trough, and cupolas of this granite are seen as the Dartmoor, Bodmin Moor, St. Austell, Carnmenellis, Land’s End and Scilly Isles intrusions (see IGN-SW-E).

The Cornubian Massif also contains a feature highly typical of continent–continent collision, The Lizard Complex. This is a remnant of the old ocean that once existed between Gondwana and Laurasia (sometimes called the ‘Rheic Ocean’). Its emplacement and age are still not fully understood, but it was undoubtedly pushed North from the Variscan Suture Zone (which probably lay somewhere within what is now the Bay of Biscay) along a large-scale, major crustal thrust. The igneous rocks are encompassed within their own GCR Block, Igneous Rocks of South-West England. See IGN-SW-E.

Site List

Your selection found 31 GCR sites. Sites are sorted alphabetically by country, local authority and then by site name -
CodeNameCountryLocal AuthorityGrid RefGCR Site Account
2927Booby`s Bay to Trevose HeadEnglandCornwall and Isles of ScillySW857751Not available
1639BoscastleEnglandCornwall and Isles of ScillySX095915Not available
1637Bude CoastEnglandCornwall and Isles of ScillySS211070Not available
2926Cotty`s Point, PerranporthEnglandCornwall and Isles of ScillySW758549Not available
2718Crocadon QuarryEnglandCornwall and Isles of ScillySX392657Not available
2714Godrevy PointEnglandCornwall and Isles of ScillySW580433Not available
2925Godrevy Point and Strap RocksEnglandCornwall and Isles of ScillySW579415Not available
2717Greystone QuarryEnglandCornwall and Isles of ScillySX365806Not available
1640Millook to Foxhole PointEnglandCornwall and Isles of ScillySS186005Not available
1717Polzeath to Pentire PointEnglandCornwall and Isles of ScillySW931799Not available
2849PorthlevenEnglandCornwall and Isles of ScillySW627254Not available
2846Porthmissen BridgeEnglandCornwall and Isles of ScillySW892765Not available
2850Rosemullion HeadEnglandCornwall and Isles of ScillySW797279Not available
1718Rusey Cliff to BuckatorEnglandCornwall and Isles of ScillySX123937Not available
1635Smith`s Cliff To Tintagel IslandEnglandCornwall and Isles of ScillySX056891Not available
2848Stepper PointEnglandCornwall and Isles of ScillySW914782Not available
1636Trebarwith StrandEnglandCornwall and Isles of ScillySX049867Not available
1638Widemouth To Saltstone StrandEnglandCornwall and Isles of ScillySS194012Not available
2932Ashburton Road CuttingsEnglandDevon CCSX747681Not available
2894Beesands - HallsandsEnglandDevon CCSX819402Not available
2928Bovisand BayEnglandDevon CCSX490496Not available
2847Cholwell BrookEnglandDevon CCSX509808Not available
2934Clovelly to Mouth MillEnglandDevon CCSS317251Not available
2715Coryton QuarryEnglandDevon CCSX466849Not available
2924Hartland PointEnglandDevon CCSS274264Not available
2923Ilfracombe Coastal SectionsEnglandDevon CCSS536480Not available
2929Jennycliff BayEnglandDevon CCSX489515Not available
2716Lydford GorgeEnglandDevon CCSX501832Not available
2713Meldon QuarryEnglandDevon CCSX570927Not available
2930North Sands Bay, SalcombeEnglandDevon CCSX728378Not available
2719Welcombe MouthEnglandDevon CCSS212179Not available
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