map of
Great Britain demonstrates, the
geology of the
UK is varied and complex. The
physical geography of the UK varies greatly.
England consists of mostly lowland terrain, with upland or mountainous terrain only found north-west of the
Tees–Exe line. The upland areas include the
Lake District, the
Pennines,
North York Moors,
Exmoor and
Dartmoor. The lowland areas are typically traversed by ranges of low hills, frequently composed of
chalk, and flat plains.
Scotland is the most mountainous country in the UK and its physical geography is distinguished by the
Highland Boundary Fault which traverses the Scottish mainland from
Helensburgh to
Stonehaven. The faultline separates the two distinctively different regions of the
Highlands to the north and west, and the
Lowlands to the south and east. The Highlands are predominantly mountainous, containing the majority of Scotland's mountainous landscape, while the Lowlands contain flatter land, especially across the
Central Lowlands, with upland and mountainous terrain located at the
Southern Uplands.
Wales is mostly mountainous, though
south Wales is less mountainous than
north and
mid Wales.
Northern Ireland consists of mostly hilly landscape and its geography includes the
Mourne Mountains as well as
Lough Neagh, at , the largest body of water in the UK. The overall
geomorphology of the UK was shaped by a combination of forces including
tectonics and
climate change, in particular
glaciation in northern and western areas. The tallest mountain in the UK (and British Isles) is
Ben Nevis, in the
Grampian Mountains, Scotland. The longest river is the
River Severn which flows from
Wales into England. The largest lake by surface area is
Lough Neagh in Northern Ireland, though Scotland's
Loch Ness has the largest volume.
Geology The geology of the UK is complex and diverse, a result of it being subject to a variety of
plate tectonic processes over a very extended period of time. Changing latitude and sea levels have been important factors in the nature of sedimentary sequences, whilst successive continental collisions have affected its
geological structure with major faulting and folding being a legacy of each
orogeny (mountain-building period), often associated with
volcanic activity and the metamorphism of existing rock sequences. As a result of this eventful geological history, the UK shows a rich variety of
landscapes.
Precambrian The oldest rocks in the British Isles are the
Lewisian gneisses, metamorphic rocks found in the far north-west of Scotland and in the
Hebrides (with a few small outcrops elsewhere), which date from at least 2,700 Ma (Ma = million years ago). South and east of the gneisses are a complex mixture of rocks forming the North West
Highlands and
Grampian Highlands in Scotland. These are essentially the remains of folded
sedimentary rocks that were deposited between 1,000 Ma and 670 Ma over the gneiss on what was then the floor of the
Iapetus Ocean.
Paleozoic At 520 Ma, what is now Great Britain was split between two
continents; the north of Scotland was located on the continent of
Laurentia at about 20° south of the
equator, while the rest of the country was on the continent of
Gondwana near the
Antarctic Circle. In Gondwana, England and
Wales were largely submerged under a shallow sea studded with
volcanic islands. The remains of these islands underlie much of central England with small outcrops visible in many places. About 500 Ma southern Britain, the east coast of
North America and south-east
Newfoundland broke away from Gondwana to form the continent of
Avalonia, which by 440 Ma had drifted to about 30° south. During this period north Wales was subject to
volcanic activity. The remains of these volcanoes are still visible, one example of which is
Rhobell Fawr dating from 510 Ma. Large quantities of volcanic
lava and ash known as the
Borrowdale Volcanics covered the
Lake District and this can still be seen in the form of mountains such as
Helvellyn and
Scafell Pike. Between 425 and 400 Ma
Avalonia had joined with the continent of
Baltica, and the combined landmass collided with
Laurentia at about 20° south, joining the southern and northern halves of
Great Britain together. The resulting
Caledonian Orogeny produced an
Alpine-style mountain range in much of north and west Britain. The collision between continents continued during the
Devonian period, producing uplift and subsequent erosion, resulting in the deposition of numerous sedimentary rock layers in lowlands and seas. The
Old Red Sandstone and the contemporary volcanics and marine sediments found in
Devon originated from these processes. Around 360 Ma 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 and the
Peak District of
Derbyshire. Later,
river deltas formed and the sediments deposited were colonised by
swamps and
rain forest. It was in this environment that the
Coal Measures were formed, the source of the majority of Britain's extensive
coal reserves. Around 280 Ma the
Variscan orogeny mountain-building period occurred, again due to collision of continental plates, causing major deformation in south-west England. The general region of Variscan folding was south of an east–west line roughly from south
Pembrokeshire to
Kent. Towards the end of this period
granite was formed beneath the overlying rocks of
Devon and
Cornwall, now exposed at
Dartmoor and
Bodmin Moor. 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 subject to a hot arid desert climate with frequent flash floods leaving deposits that formed beds of red
sedimentary rock.
Mesozoic As Pangaea drifted during the
Triassic, Great Britain moved away from the equator until it was between 20° and 30° north. 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.
Pangaea began to break up at the start of the
Jurassic period. Sea levels rose and Britain drifted on the
Eurasian Plate to between 31° and 40° north. Much of Britain was under water again, and
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 seafloor during this time resulted in the formation of
North Sea oil and
natural gas. 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 was 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.
Cenozoic 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
Lundy Island in the
Bristol Channel. The
Alpine Orogeny that took place in Europe about 50 Ma, was responsible for the folding of strata in southern England, producing 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. The major changes during the last 2 million years were brought about by
several recent ice ages. The most severe was the
Anglian Glaciation, with ice up to 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. During the most recent
Devensian glaciation, which ended a mere 10,000 years ago, the icesheet reached south to
Wolverhampton and
Cardiff. 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 the
Oslo region of
Norway and deposited on the coast of
Yorkshire. Amongst the most significant geological features created during the last twelve thousand years are the
peat deposits of Scotland, and of coastal and upland areas of England and Wales. At the present time Scotland is continuing to rise as a result of the weight of Devensian ice being lifted. Southern and eastern England is sinking, generally estimated at 1 mm ( in) per year, with the London area sinking at double the speed partly due to the continuing
compaction of the recent clay deposits.
Mountains and hills is the highest peak in the
UK. The ten tallest
mountains in the UK are all found in Scotland. The highest peaks in each part of the UK are: • Scotland:
Ben Nevis, • Wales:
Snowdon (Yr Wyddfa), (
Snowdonia), • England:
Scafell Pike (
Cumbrian Mountains), • Northern Ireland:
Slieve Donard (
Mourne Mountains), The ranges of mountains and
hills in the UK include: • Scotland:
Cairngorms,
Scottish Highlands,
Southern Uplands,
Grampian Mountains,
Monadhliath Mountains,
Ochil Hills,
Campsie Fells,
Cuillin • Wales:
Brecon Beacons (Bannau Brycheiniog),
Cambrian Mountains (Mynyddoedd Cambria),
Clwydian Hills (Bryniau Clwyd),
Snowdonia (Eryri),
Black Mountains (Y Mynyddoedd Duon),
Preseli Hills (Y Preseli) • England:
Cheviot Hills,
Chilterns,
Cotswolds,
Dartmoor,
Lincolnshire Wolds,
Exmoor,
Lake District,
Malvern Hills,
Mendip Hills,
North Downs,
Peak District,
Pennines,
South Downs,
Shropshire Hills,
Yorkshire Wolds • Northern Ireland:
Mourne Mountains,
Antrim Plateau,
Sperrin Mountains The lowest point of the UK is in
the Fens of
East Anglia, in England, parts of which lie up to below
sea level.
Rivers and lakes ;Main articles: •
List of lakes and lochs in the United Kingdom; •
List of rivers of the United Kingdom; •
List of waterfalls of the United Kingdom. The longest river in the UK is the
River Severn () which flows through both Wales and England. The longest rivers in the UK contained fully within each of its constituent nations are: • England:
River Thames () • Scotland:
River Tay () • Northern Ireland:
River Bann () • Wales:
River Usk () The largest lakes (by surface area) in the UK by country are: • Northern Ireland:
Lough Neagh () • Scotland:
Loch Lomond () • England:
Windermere () • Wales:
Llyn Tegid (Bala Lake) () The deepest lake in the UK is
Loch Morar with a maximum depth of ;
Loch Ness is second at deep. The deepest lake in England is
Wastwater which achieves a depth of .
Loch Ness is the UK's largest lake in terms of volume.
Artificial waterways As a result of its industrial history, the United Kingdom has an extensive system of
canals, mostly built in the early years of the
Industrial Revolution, before the rise of competition from the
railways. The United Kingdom also has numerous
dams and
reservoirs to store water for drinking and industry. The generation of
hydroelectric power is rather limited, supplying less than 2% of British electricity, mainly from the Scottish Highlands.
Coastline The UK has a
coastline which measures about . The heavy indentation of the coastline helps to ensure that no location is more than from tidal waters. The UK claims jurisdiction over the
continental shelf, as defined in continental shelf orders or in accordance with agreed upon boundaries, an exclusive fishing zone of , and territorial sea of . The UK has an
Exclusive Economic Zone of in
Europe. However, if all crown dependencies and overseas territories are included then the total EEZ is which is the 5th largest in the world.
Inlets •
Cardigan Bay •
Lyme Bay •
Bristol Channel •
Thames Estuary •
Morecambe Bay •
Solway Firth •
The Wash •
Humber Estuary •
Firth of Forth •
Firth of Tay •
Moray Firth •
Firth of Clyde •
Firth of Lorn Headlands The geology of the United Kingdom is such that there are many headlands along its coast. A
list of headlands of the United Kingdom details many of them.
Tidal flats A recent global remote sensing analysis suggested that there were of tidal flats in the United Kingdom, making it the 12th ranking country in terms of how much tidal flat occurs there.
Islands In total, it is estimated that the UK is made up of over one thousand small islands, the majority located off the north and west coasts of Scotland. About 130 of these are inhabited according to the 2001 census. The largest island in the UK is
Great Britain. The largest islands by constituent country are
Lewis and Harris in Scotland at , Wales'
Anglesey at , the
Isle of Wight in England at , and
Rathlin Island in Northern Ireland at roughly ;
Climate The climate of the UK is generally
temperate, although significant local variation occurs, particularly as a result of altitude and distance from the coast. In general the south of the country is warmer than the north, and the west wetter than the east. Due to the warming influence of the
Gulf Stream, the UK is significantly warmer than some other locations at a similar latitude, such as
Newfoundland. The prevailing winds are southwesterly, from the
North Atlantic Current. More than 50% of the days are overcast. There are few natural hazards, although there can be strong winds and floods, especially in winter. Average annual rainfall varies from over in the
Scottish Highlands down to in
Cambridge. The county of
Essex is one of the driest in the UK, with an average annual rainfall of around , although it typically rains on over 100 days per year. In some years rainfall in Essex can be below , less than the average annual rainfall in
Jerusalem and
Beirut. The highest temperature recorded in the UK was at
Coningsby in
Lincolnshire, on 20 July 2022. The lowest was recorded at
Braemar in the
Grampian Mountains, Scotland, on 11 February 1895 and 10 January 1982 and
Altnaharra, also in Scotland, on 30 December 1995. ==Human geography==