Carboniferous period[edit]
Around 360 Ma at the start of the Carboniferous period Great Britain was lying at the equator, covered by the warm shallow waters of the Rheic Ocean, during which time the Carboniferous Limestone was deposited, as found in the Mendip Hills, north and south Wales, in the Peak District of Derbyshire, north Lancashire, the northern Pennines and southeast Scotland. Caves developed more recently in the limestone of some of these areas by the action of carbonic acid and other organic acids in rainwater and groundwater.
These were followed by dark marine shales, siltstones, and coarse sandstones of the Millstone Grit. Later, river deltas formed and the sediments deposited were colonised by swamps and rain forest. It was in this environment that the cyclic Coal Measures were formed, the source of the majority of Britain's extensive coal reserves that powered the Industrial Revolution. Coal can be found in many areas of Britain, as far north as the Midland Valley of Scotland, as far south as Kent, although coal mining has largely been concentrated in the English Midlands, northern England and Wales.
Throughout the period, southwest England in particular was affected by the collision of continental plates. The mountain building period known as the Variscan orogeny, which occurred around 280 Ma, caused major deformation in south west England. Towards the end of this period granite was formed beneath the overlying rocks of Devon and Cornwall, now exposed at Dartmoor and Bodmin Moor, giving rise to mineralised deposits of copper and tin. The general region of Variscan folding was south of an east–west line roughly from south Pembrokeshire to Kent. The main tectonic pressure was from the south or south-east, and there developed dextral strike-slip faulting. The Devon-Cornwall massif may originally have been some distance further east, then to be moved westwards. Lesser Variscan folding took place as far north as Derbyshire and Berwick-upon-Tweed.
By the end of the Carboniferous period the various continents of the Earth had fused to form the super-continent of Pangaea. Britain was located in the interior of Pangea where it was again subject to a hot arid desert climate with frequent flash floods leaving deposits that formed beds of red sedimentary rock, somewhat similar to the later, Triassic New Red Sandstone.
Permian period[edit]
The Permian was characterised for 30 million years by arid desert conditions and the erosion of the land that had uplifted in the Variscan Orogeny, southwest England and adjacent areas of the present-day English Channel. Later, much of Great Britain was submerged in shallow waters as the polar ice sheets melted and the Tethys Ocean and Zechstein Sea formed, depositing shale, limestone, gravel, and marl, before finally receding to leave a flat desert with salt pans.
Mesozoic era[edit]
Triassic period[edit]
As Pangaea drifted during the Triassic, Great Britain moved away from the equator until it was between 20° and 30° north. Red beds, including sandstones and red mudstones form the main sediments of the New Red Sandstone. The remnants of the Variscan uplands in France to the south were eroded down, resulting in layers of the New Red Sandstone being deposited across central England, and in faulted basins in Cheshire and the Irish Sea. A basin developed in the Hampshire region around this time. Rifting occurred within and around Britain and Ireland, prior to the breakup of the super-continent in the Jurassic period.
Rock fragments found near Bristol appear to indicate that in 214 Ma Great Britain was showered with a fine layer of debris from an asteroid impact at the Manicouagan Impact Crater in Canada, although this is still being debated.
Jurassic period[edit]
As the Jurassic period began, Pangaea began to break up, sea levels rose and Britain and Ireland drifted on the Eurasian Plate to between 30° and 40° north. With much of the British Isles under water again, sedimentary rocks were deposited and can now be found underlying much of England from the Cleveland Hills of Yorkshire to the Jurassic Coast in Dorset. These include sandstones, greensands, oolitic limestone of the Cotswold Hills, corallian limestone of the Vale of White Horse and the Isle of Portland.
The burial of algae and 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 salt deposits formed as the sea levels fell to form the swamps and salty lakes and lagoons that were home to dinosaurs.[citation needed]
Cretaceous period[edit]
The modern continents having formed, the Cretaceous saw the formation of the Atlantic Ocean, gradually separating northern Scotland from North America. The land underwent a series of uplifts to form a fertile plain.
After 20 million years or so, the seas started to flood the land again until much of Britain and Ireland were again below the sea, though sea levels frequently changed. Chalk and flints were deposited over much of Great Britain, now notably exposed at the White Cliffs of Dover and the Seven Sisters, and also forming Salisbury Plain. The high sea levels left only small areas of land exposed, which accounts for the general lack of land-origin sand, mud or clay sediments found from around this time. Some of the late Cretaceous strata are, in fact, almost pure chalk.
Cenozoic era[edit]
Palaeogene period[edit]
In the early Palaeogene period between 63 and 52 Ma, the last volcanic rocks in Great Britain were formed. The major eruptions at this time produced the Antrim Plateau, the basaltic columns of the Giant's Causeway and the lavas and igneous intrusions of the Inner Hebrides of Scotland.
The Alpine Orogeny that took place about 50 Ma was responsible for the shaping of the London Basin syncline, the Weald-Artois Anticline to the south, the North Downs, South Downs and Chiltern Hills.
During the period the North Sea formed, Britain was uplifted. Some of this uplift was along old lines of weakness left from the Caledonian and Variscan Orogenies long before. The uplifted areas were then eroded, and further sediments, such as the London Clay, were deposited over southern England, while the English Channel was characterised by mud flats and river-deposited sands. Much of the midlands and north of England may have been covered by Jurassic and Cretaceous deposits at the start of the Palaeogene, but these were lost through erosion. By 35 Ma the landscape was colonised by trees such as beech, oak, redwood and palm, along with grasses.
Neogene period[edit]
Miocene and Pliocene epochs[edit]
In the Miocene and Pliocene epochs of the Neogene, further uplift and erosion occurred, particularly in Wales, the Pennines, and the Scottish 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.
Quaternary period[edit]
Pleistocene epoch[edit]