Also Known As The

Total Page:16

File Type:pdf, Size:1020Kb

Also Known As The

A summary of the orogenies that affected the UK

THE CALEDONIAN OROGENY

Effects seen in Scotland, the Southern Uplands, the Lake District and Snowdonia

Effects seen in Pre-Cambrian, Ordovician and Silurian rocks

Occurred between 600 & 400Ma

Created the Caledonian fold belt

A result of the Laurentian continent (Greenland and Canada) colliding with Gondwanaland (Scandanavia and Baltic continent)

Involved the closure of the Iapetus Ocean – between Scotland and England

Resulted in volcanics in Snowdonia (Mount Snowdon) and the Lake District (ScaFell Pike, Old Man of Coniston etc.)

Main trend of fold axes = NE-SW Associated with the Moine Thrust, the Highland Boundary Fault, the Great Glen Fault and the Southern Uplands Fault – with NE-SW trends

Associated with major intrusions in Scotland eg. the Carrock Fell gabbro

THE VARISCAN OROGENY

Also known as the AMORICAN OROGENY

Also known as the HERCYNIAN OROGENY

Effects seen in Devon and Cornwall, South Wales, and northern England

Effects seen in Devonian & Carboniferous rocks

Occurred about 290Ma

Created the Variscan mountain belt

A result of southern Europe colliding with the Caledonian continent to from Pangaea - supercontinent Involved the closure of the Rheic Ocean – between South Wales and Devon and Cornwall

Resulted in intrusions and volcanics in Devon and Cornwall – including the Cornubian batholith - granites

Resulted in intense folding such as that at Hartland Quay, Devon and Millook, Cornwall along with folding of the South Wales coal fields

Main trend of fold axes = E – W

Associated with the formation of the Lizard Thrust, the Pennine Block faults and renewed subsidence in the Scottish Rift valley

Associated with the intrusion of the Whin Sill

THE ALPINE OROGENY

Effects seen mainly in South East of England

Effects seen in Permian, Triassic, Jurassic, Cretaceous and Tertiary rocks.

Occurred about 25 - 30Ma

Created the Alpine mountain belt – the Alps

Created the Wealden Anticline

Created the Lulworth Crumple, Dorset

Main trend of fold axes = E-W

Re-activated many pre-existing fault lines

Was centred in Southern Europe and the UK only on the edge of the mountains formed

A result of northward movement of Africa colliding with Europe

The north Atlantic was opening up at the same time – producing the flood basalts seen in Northern Ireland (Giants Causeway) and north-east Scotland (Staffa and Fingal’s Cave) and dyke swarms across northern England and southern Scotland.

Recommended publications