Editing Geography of the United Kingdom (section)

==Physical geography==
[[File:uk topo en.jpg|thumb|UK's topography]]
[[File:Geological map of Great Britain.jpg|thumb|right|As this [[geology|geological]] map of [[Great Britain]] demonstrates, the [[geology]] of the [[United Kingdom|UK]] is varied and complex.]]
The [[physical geography]] of the UK varies greatly. [[Geography of England|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. [[Geography of Scotland|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 [[Scottish Highlands|Highlands]] to the north and west, and the [[Scottish Lowlands|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]]. [[Geography of Wales|Wales]] is mostly mountainous, though [[south Wales]] is less mountainous than [[North Wales|north]] and [[mid Wales]]. [[Geography of Ireland|Northern Ireland]] consists of mostly hilly landscape and its geography includes the [[Mourne Mountains]] as well as [[Lough Neagh]], at {{convert|388|km2|sqmi|0}}, the largest body of water in the UK.<ref>{{cite web|url=http://cain.ulst.ac.uk/ni/geog.htm|title=Geography of Northern Ireland|publisher=University of Ulster|access-date=25 September 2017}}</ref>

The overall [[geomorphology]] of the UK was shaped by a combination of forces including [[tectonics]] and [[Climate variability and change|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 ===
{{See also|Geology of Great Britain|Geology of Ireland}}

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 of Great Britain|geological structure]] with major faulting and folding being a legacy of each [[orogeny]] (mountain-building period), often associated with [[volcanism|volcanic]] activity and the metamorphism of existing rock sequences. As a result of this eventful geological history, the UK shows a rich variety of [[landscape]]s.<ref name=Toghill>{{cite book |title=The Geology of Britain: An Introduction |last=Toghill |first=Peter |year=2000 |publisher=Swan Hill Press |location= Shrewsbury|isbn=1-85310-890-1 }}</ref>

====Precambrian====
The oldest rocks in the British Isles are the [[Lewisian gneiss]]es, 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 [[Scottish Highlands|Highlands]] and [[Grampian]] Highlands in Scotland. These are essentially the remains of folded [[sedimentary rock]]s that were deposited between 1,000 Ma and 670 Ma over the gneiss on what was then the floor of the [[Iapetus Ocean]].

====Palaeozoic====
At 520 Ma, what is now Great Britain was split between two [[continent]]s; 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 [[volcano|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 (island)|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 [[volcanism|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 [[Alps|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 delta]]s formed and the sediments deposited were colonised by [[swamp]]s 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]]. [[Great Britain|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 rock]]s were deposited and can now be found underlying much of England from the [[Cleveland Hills]] of [[Yorkshire]] to the [[Jurassic Coast]] in [[Geology of Dorset|Dorset]]. These include [[sandstone]]s, [[greensand (geology)|greensand]]s, [[oolite|oolitic]] [[limestone]] of the [[Cotswold Hills]], [[corallian limestone]] of the [[Vale of White Horse]] and the [[Portland Limestone|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]].

[[File:Geological map - William Smith, 1815 - BL.jpg|thumb|1815 geological by [[William Smith (geologist)|William Smith]]]]
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 [[flint]]s were deposited over much of Great Britain, now notably exposed at the [[White Cliffs of Dover]] and the [[Seven Sisters, Sussex|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 [[County Antrim|Antrim Plateau]], the [[basalt]]ic 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 [[Tectonic uplift|uplift]]ed. 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 [[Quaternary glaciation|several recent ice ages]]. The most severe was the [[Anglian Stage|Anglian Glaciation]], with ice up to {{convert|1000|m|ft|abbr=on}} 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 [[fjord]]s of the west coast of Scotland, the [[glaciated valley|U-shaped valleys]] of the [[Lake District]] and [[Glacial erratic|erratic]]s (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&nbsp;mm ({{frac|25}}&nbsp;in) per year, with the London area sinking at double the speed partly due to the continuing [[Compaction (geology)|compaction]] of the recent clay deposits.

===Mountains and hills===
[[File:BenNevis2005.jpg|thumb|At {{convert|1345|m}}, [[Ben Nevis]] is the highest peak in the [[United Kingdom|UK]].]]

{{Main|List of mountains and hills of the United Kingdom}}

The ten tallest [[mountain]]s in the UK are all found in Scotland. The highest peaks in each part of the UK are:
*Scotland: [[Ben Nevis]], {{convert|1345|m}}
*Wales: [[Snowdon]] (Yr Wyddfa), ([[Snowdonia]]), {{convert|1085|m}}
*England: [[Scafell Pike]] ([[Cumbrian Mountains]]), {{convert|978|m}}
*Northern Ireland: [[Slieve Donard]] ([[Mourne Mountains]]), {{convert|852|m}}

The ranges of mountains and [[hill]]s in the UK include:
*Scotland: [[Cairngorms]], [[Scottish Highlands]], [[Southern Uplands]], [[Grampian Mountains (Scotland)|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, Wales|Black Mountains]] (Y Mynyddoedd Duon), [[Preseli Hills]] (Y Preseli)
*England: [[Cheviot Hills]], [[Chilterns]], [[Cotswolds]], [[Dartmoor]], [[Lincolnshire Wolds]], [[Exmoor]], [[Lake District]], [[Malvern Hills AONB|Malvern Hills]], [[Mendip Hills]], [[North Downs]], [[Peak District]], [[Pennines]], [[South Downs]], [[Shropshire Hills AONB|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 {{convert|4|m}} 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]] ({{convert|220|mi|km|abbr=on|disp=semicolon}}) 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]] ({{convert|215|mi|km|abbr=on|disp=semicolon}})
*Scotland: [[River Tay]] ({{convert|117|mi|km|abbr=on|disp=semicolon}})
*Northern Ireland: [[River Bann]] ({{convert|76|mi|km|abbr=on|disp=semicolon}})
*Wales: [[River Usk]] ({{convert|78|mi|km|abbr=on|disp=semicolon}})

The largest lakes (by surface area) in the UK by country are:
*Northern Ireland: [[Lough Neagh]] ({{convert|147.39|mi2|km2|abbr=on|disp=semicolon}})
*Scotland: [[Loch Lomond]] ({{convert|27.46|mi2|km2|abbr=on|disp=semicolon}})
*England: [[Windermere]] ({{convert|5.69|mi2|km2|abbr=on|disp=semicolon}})
*Wales: [[Bala Lake]] (Llyn Tegid) ({{convert|1.87|mi2|km2|abbr=on|disp=semicolon}})

The deepest lake in the UK is [[Loch Morar]] with a maximum depth of {{convert|309|m}}; [[Loch Ness]] is second at {{convert|228|m}} deep. The deepest lake in England is [[Wastwater]] which achieves a depth of {{convert|79|m}}.

[[Loch Ness]] is the UK's largest lake in terms of volume.

===Artificial waterways===
''Main articles:'' [[Waterways in the United Kingdom]], [[Canals of Great Britain]], [[List of dams and reservoirs in United Kingdom|Dams and reservoirs in United Kingdom]]

As a result of its industrial history, the United Kingdom has an extensive system of [[canal]]s, mostly built in the early years of the [[Industrial Revolution]], before the rise of competition from the [[railway]]s. The United Kingdom also has numerous [[dam]]s and [[reservoir (water)|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===
{{Main|Coastline of the United Kingdom}}
[[File:United Kingdom maritime claims.png|300px|right|thumb|United Kingdom maritime claims]]
The UK has a [[coastline]] which measures about {{convert|12429|km|abbr=on}}.<ref>{{cite web|author=The Department for Environment, Food & Rural Affairs|title=Factsheet Marine Conservation Zones|url=http://archive.defra.gov.uk/environment/marine/documents/interim2/mcz-factsheet-why.pdf|year=2009|website=defra.gov.uk|publisher=DEFRA|access-date=21 April 2014|archive-url=https://web.archive.org/web/20140423042806/http://archive.defra.gov.uk/environment/marine/documents/interim2/mcz-factsheet-why.pdf|archive-date=23 April 2014|url-status=dead}}</ref> The heavy indentation of the coastline helps to ensure that no location is more than {{convert|125|km|abbr=on}} 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 {{convert|200|nmi|km mi|1|abbr=on|lk=in}}, and territorial sea of {{convert|12|nmi|km mi|1|abbr=on}}.

The UK has an [[Exclusive economic zone of the United Kingdom|Exclusive Economic Zone]] of {{convert|773676|km2|mi2|abbr=on}} in [[Europe]]. However, if all crown dependencies and overseas territories are included then the total EEZ is {{convert|6805586|km2|mi2|abbr=on}} 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 {{convert|2697|km2|abbr=on}} of tidal flats in the United Kingdom, making it the 12th ranking country in terms of how much tidal flat occurs there.<ref>{{cite journal |last1=Murray |first1=N.J. |last2=Phinn |first2=S.R. |last3=DeWitt |first3=M. |last4=Ferrari |first4=R. |last5=Johnston |first5=R. |last6=Lyons |first6=M.B. |last7=Clinton |first7=N. |last8=Thau |first8=D. |last9=Fuller |first9=R.A. |title=The global distribution and trajectory of tidal flats |journal=Nature |date=2019 |volume=565 |issue=7738 |pages=222–225 |doi=10.1038/s41586-018-0805-8 |pmid=30568300 |s2cid=56481043 |url=https://www.nature.com/articles/s41586-018-0805-8}}</ref>

===Islands===
{{Main|List of islands of the United Kingdom}}
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 {{convert|841|sqmi|abbr=on}}, Wales' [[Anglesey]] at {{convert|276|sqmi|abbr=on}}, the [[Isle of Wight]] in England at {{convert|147|sqmi|abbr=on}}, and [[Rathlin Island]] in Northern Ireland at roughly {{convert|6|sqmi|abbr=on}};

===Climate===
{{Main|Climate of the United Kingdom}}

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 (island)|Newfoundland]].

The prevailing winds are southwesterly, from the [[North Atlantic Current]]. More than 50% of the days are overcast.<ref>{{Cite web|url=http://www.metoffice.gov.uk/climate/uk/summaries/actualmonthly|title=25 September 2017}}</ref> There are few natural hazards, although there can be strong winds and floods, especially in winter.

Average annual rainfall varies from over {{convert|3000|mm|in|1|abbr=on}} in the [[Scottish Highlands]] down to {{convert|553|mm|in|1|abbr=on}} in [[Cambridge]]. The county of [[Essex, England|Essex]] is one of the driest in the UK, with an average annual rainfall of around {{convert|600|mm|in|1|abbr=on}}, although it typically rains on over 100 days per year. In some years rainfall in Essex can be below {{convert|450|mm|in|1|abbr=on}}, less than the average annual rainfall in [[Jerusalem]] and [[Beirut]].

The highest temperature recorded in the UK was {{convert|40.3|°C|°F}} at [[Coningsby]] in [[Lincolnshire]], on 20 July 2022.<ref>{{cite web|url=https://www.metoffice.gov.uk/about-us/press-office/news/weather-and-climate/2022/red-extreme-heat-warning-ud|title=Record breaking temperatures for the UK }}</ref> The lowest was {{convert|-27.2|°C|°F}} recorded at [[Braemar]] in the [[Grampian Mountains (Scotland)|Grampian Mountains]], Scotland, on 11 February 1895 and 10 January 1982 and [[Altnaharra]], also in Scotland, on 30 December 1995.