Jurassic period

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 includesandstones, 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.

Cretaceous period

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

Palaeogene period

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.

Miocene and Pliocene epochs

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.

Pleistocene epoch

The major changes during the Pleistocene were brought about by several recent ice ages. The most severe was the Anglian Glaciation, with ice up to 1,000 m (3300 ft) thick that reached as far south as London and Bristol. This took place between about 478,000 to 424,000 years ago, and was responsible for the diversion of the River Thames onto its present course.

There is extensive evidence in the form of stone tools that southern England was colonised by human populations during the warm Hoxnian Stage that followed the Anglian Glaciation. It is possible that the English Channel repeatedly opened and closed during this period, causing Britain to become an island from time to time. The oldest human fossils found to date in the British Isles, which include the skull of Swanscombe Man from 250,000 years ago, and the earlier Clactonian Man, also date from this period.

The Wolstonian Glaciation, between about 352,000 to 130,000 years ago, which is thought to have peaked around 150,000 years ago, was named after the village of Wolston southeast of Coventry which is thought to mark the southern limit of the ice.

The Wolstonian Stage was followed by the Ipswichian Stage, during which hippopotamus are known to have lived as far north as Leeds.

During the most recent Devensian glaciation, which is thought to have started around 115,000 years ago, peaked around 20,000 years ago and ended a mere 10,000 years ago, the Usk valleyand Wye valley were eroded by glaciers, with the icesheet itself reaching south to Wolverhampton and Cardiff. The oldest human remains in Britain or Ireland, the Red Lady of Paviland (29,000 years old) date from this time. It is thought that the country was eventually abandoned as the ice sheet reached its peak, being recolonised as it retreated. By 5,000 years ago it is thought that Great Britain was warmer than it is at present.

Among the features left behind by the ice are the fjords of the west coast of Scotland, the U-shaped valleys of the Lake District and erratics (blocks of rock) that have been transported from theOslo region of Norway and deposited on the coast of Yorkshire.