4 Variscan Orogenesis 4 Alpine Orogeny 3 North

4. Variscan Orogenesis

4. Alpine Orogeny 3. North Atlantic Tertiary Igneous Province (NATP) 2. Variscan Orogeny 1. Caledonian Orogeny

Old Red Sandstone Continent Mid-Devonian ~400 Ma

Pangaea Supercontinent Pre-Cambrian 850 Ma Carboniferous~~300 Ma

Upper Carboniferous 300 MYA – Variscan Orogenesis 1. Intense Folding 3. Regional Metamorphism e. g. Hartland Quay e. g. Delabole Slate, North Cornwall 5. Ophiolites e. g. Lizard Ophiolite Complex 2. Batholiths e. g. Dartmoor 4. Faulting e. g. Lizard Thrust Fault

Gentle open folds, Broad Haven, South Wales Less intense, more irregular folds, Bude, Devon Somerset Devon Recumbent folds, Millook Haven, north Cornwall Lizard Thrust Carboniferous rocks Granite Batholith Lizard Ophiolite Complex • Gentle folds • 2% shortening of crust • No cleavage • Open, asymmetric folds with steep southern limb • Complex folding & thrusting. • Very complex folding & extensive thrusting. • 10% shortening of crust • 50% shortening of crust • Very strong cleavage • No cleavage • Good cleavage • 65% shortening of crust

Recumbent folds, Millook Haven, north Cornwall

Less intense, more irregular folds, Bude, Devon

Gentle open folds, Broad Haven, South Wales

Plates Involved Caledonian Avalonia Laurentia Location in Britain Age Geological Structures & Trends Faults: Scottish Highlands Lower Palaeozoic Lake District 400 mya North Wales Anglesey Granite Moine Thrust batholiths: Belt e. g. Glencoul Cairngorms Thrust Skiddaw Great Glen Folds: Shap Tay Nappe Eskdale Shap Fell Ennerdale Harlech Dome Ophiolites – Ballantrae NE-SW trend Variscan ORS continent Gondwana South Wales Upper Palaeozoic Cornwall 300 mya Faults: Lizard Thrust Granite batholiths: Folds: Dartmoor Devon Millook Haven Bodmin Moor Somerset Hartland Quay Land’s End Broad Haven Scilly Isles E-W trend Alpine Europe Africa Igneous Rocks SE England Cenozoic Folds: 40 mya North & South Downs E-W trend Metamorphic Rocks Regional: Dalradian schists Ballachulish slates Easdale slates Llanberis slates Skiddaw slates Dynamic: Mylonite Regional: Delabole slates