Editing County Donegal (section)

==Geography and subdivisions==
{{Multiple image|align=right|image1=Poisoned Glen (cropped).jpg|width1=200|alt1=|image2=The Poisoned Glen - geograph.org.uk - 770833 (cropped).jpg|width2=200|alt2=|footer=The appearance of parts of County Donegal's landscape can vary from lush green in the summer to orange-brown in the winter}}
Located in the northwest corner of [[Ireland]], Donegal is the island's northernmost county. In terms of size and area, it is the largest county in Ulster and the fourth-largest county in all of Ireland. Uniquely, County Donegal shares a small border with only one other county in the [[Republic of Ireland]] – [[County Leitrim]]. The vast majority of its land border (93%) is shared with three counties of [[Northern Ireland]]: [[County Tyrone]], [[County Londonderry]] and [[County Fermanagh]]. This geographic isolation from the rest of the Republic has led to Donegal people maintaining a distinct cultural identity<ref>{{cite web |url=http://www.donegallibrary.ie/quicklinks/aboutdonegal/ |title=Donegal Library Services |publisher=Donegal Library |access-date=9 July 2013 |archive-url=https://web.archive.org/web/20131020165335/http://www.donegallibrary.ie/quicklinks/aboutdonegal/ |archive-date=20 October 2013 |url-status=dead}}</ref> and has been used to market the county with the [[slogan]] "Up here it's different".<ref name = "IE NW">[http://www.irelandnorthwest.ie/?id=28 Ireland Northwest] {{Webarchive |url=https://web.archive.org/web/20070422131117/http://www.irelandnorthwest.ie/?id=28 |date=22 April 2007 }}.</ref> While Lifford is the [[county town]], [[Letterkenny]] is by far the largest town in the county with a population of just under 20,000. Letterkenny and the nearby city of [[Derry]] form the main economic axis in the northwest of Ireland.<ref>{{cite web |url=http://www.sinnfein.ie/contents/16086 |title=Derry and Donegal Sinn Féin Councillors join forces to push North West tourism |publisher=Sinnfein.ie |date=16 February 2009 |access-date=9 July 2013 |archive-date=3 June 2013 |archive-url=https://web.archive.org/web/20130603121447/http://www.sinnfein.ie/contents/16086 |url-status=live}}</ref> Indeed, what became the City of Derry was officially part of County Donegal up until 1610.<ref name="Brian Lacy 1983">Brian Lac[e]y (Editor), ''Archaeological Survey of County Donegal'', p. 1. [[Donegal County Council]], Lifford, 1983.</ref>
It is part of the [[Northern and Western Region]] (a [[NUTS statistical regions of Ireland|NUTS 2 European statistical Region]]), within which it is part of the [[Border Region|Border]] strategic planning area.<ref name=si573>{{cite ISB |year=2014 |type=si |number=573 |name=Local Government Act 1991 (Regional Assemblies) (Establishment) Order 2014 |date=16 December 2014 |access-date=11 March 2022}}</ref>
[[File:Derry from the International Space Station 2013-03-17.jpg|thumb|The [[Inishowen Peninsula]] as seen from the [[International Space Station]]]]

===Baronies and townlands===
{{See also|List of baronies of Ireland|List of townlands of County Donegal}}
There are eight historic [[Barony (Ireland)|baronies]] in the county.<ref>[https://www.logainm.ie/en/s?txt=in:100002&cat=BAR Placenames Database of Ireland] {{Webarchive |url=https://web.archive.org/web/20210121202131/https://www.logainm.ie/en/s?txt=in:100002&cat=BAR |date=21 January 2021 }} – Baronies.</ref> While baronies continue to be officially defined units, they ceased to have any administrative function following the [[Local Government (Ireland) Act 1898|Local Government Act 1898]], and any changes to county boundaries after the mid-19th century are not reflected in their extent. The last boundary change of a barony in Donegal was in 1851 when the barony of Inishowen was divided into Inishowen East and Inishowen West. The barony of Kilmacrennan covers a large portion of northwest Donegal and is the largest in the county. With an area of {{cvt|312,410|acre|km2|0}}, Kilmacrennan is also the largest barony in Ireland, being roughly equal in size to [[County Monaghan]]. The smallest barony is Inishowen West, at {{cvt|77,149|acres|km2}}.
{|class="wikitable sortable collapsible nowrap" style="font-size: 100%;"
|+ Historic baronies of County Donegal
|-
! Barony !! Irish name !! Area<ref>{{cite web |url=https://www.townlands.ie/donegal/ |title=Townlands in Co. Donegal |work=townlands.ie |access-date=23 July 2021 |archive-date=6 September 2021 |archive-url=https://web.archive.org/web/20210906181631/https://www.townlands.ie/donegal/ |url-status=live}}</ref><br /><small>(acres)</small>
|-
| [[Banagh]] || ''Báinigh'' || 179,090
|-
| [[Boylagh]] || ''Baollaigh'' || 157,429
|-
| [[Inishowen East]] || ''Inis Eoghain Thoir'' || 124,325
|-
| [[Inishowen West]] || ''Inis Eoghain Thiar'' || {{0}}77,149
|-
| [[Kilmacrenan (barony)|Kilmacrennan]] || ''Cill Mhic Réanáin'' || 312,410
|-
| [[Raphoe North]] || ''Ráth Bhoth Thuaidh'' || {{0}}80,388
|-
| [[Raphoe South]] || ''Ráth Bhoth Theas'' || 141,308
|-
| [[Tirhugh]] || ''Tír Aodha'' || 128,602
|}

Townlands are the smallest officially defined geographical divisions in Ireland. There are 2,787 townlands in Donegal and an additional 47 historic town boundaries. These town boundaries are registered as their own townlands and are much larger than rural townlands. The smallest rural townlands in Donegal are just 1 acre in size, most of which are either lough islands or offshore islets (Corragh Island, Bishop's Island, Juniper Island, O'Donnell's Island, etc.). The largest rural townland in Donegal is 6,053 acres (Tawnawully Mountains). The average size of a townland in the county (excluding towns) is 438 acres.

===Informal districts===
[[File:Northern Lights in Donegal, 2014 (1).jpg|thumb|[[Aurora borealis]] (''na Saighneáin'') over Malin Head]]
The county may be informally divided into a number of traditional districts. There are two [[Gaeltacht]] districts in the west: [[The Rosses]] ({{langx|ga|Na Rosa}}), centred on the town of [[Dungloe]] ({{langx|ga|An Clochán Liath}}), and [[Gweedore]] ({{langx|ga|Gaoth Dobhair}}). Another Gaeltacht district is located in the north-west: [[Cloughaneely]] ({{langx|ga|Cloich Chionnaola}}), centred on the town of [[Falcarragh]] ({{langx|ga|An Fál Carrach}}). The most northerly part of the island of Ireland is the location for three [[peninsula]]s: [[Inishowen]], [[Fanad]] and [[Rosguill]]. The main population centre of Inishowen, Ireland's largest peninsula, is [[Buncrana]]. In the east of the county lies the [[River Finn (County Donegal)|Finn Valley]] (centred on [[Ballybofey]]) and The Laggan district (not to be confused with the [[Lagan Valley]] in the south of [[County Antrim]]), which is centred on the town of [[Raphoe]].

===Geography===
[[File:Slieve League (15919171422).jpg|alt=Slieve League panorama|thumb|[[Slieve League]] cliffs, the second tallest in Ireland]]
[[File:Glengesh Pass.jpg|thumb|left|Glengesh Pass, near [[Ardara, County Donegal|Ardara]]]]
Donegal is the most mountainous county in Ulster. It consists of two ranges of low mountains, the [[Derryveagh Mountains]] in the north and the [[Blue Stack Mountains]] in the south, with [[Errigal]] at {{cvt|751|m|ft|0}} the highest peak, making it the 11th-highest [[List of Irish counties by highest point|county top]] in Ireland. It has a deeply indented coastline forming natural [[sea lough]]s, of which [[Lough Swilly]] and [[Lough Foyle]] are the most notable. Donegal boasts the [[List of Irish counties by coastline|longest mainland coastline]] of any county in Ireland, and has either the longest or third longest total coastline (including islands), depending on how it is measured. Estimates of the length of the coastline range from less than {{cvt|1000|km|mi|0}} to {{cvt|1235|km|mi|0}}.<ref>{{cite web |url=https://research.thea.ie/bitstream/handle/20.500.12065/1521/Collins%2C%20Anthony%201996.pdf?sequence=7&isAllowed=y |title=Managing the Donegal Coast in the Twenty-first Century |website=research.thea.ie |publisher=[[Institute of Technology, Sligo]] |accessdate=13 July 2021 |archive-date=13 July 2021 |archive-url=https://web.archive.org/web/20210713101438/https://research.thea.ie/bitstream/handle/20.500.12065/1521/Collins,%20Anthony%201996.pdf?sequence=7&isAllowed=y |url-status=live}}</ref> The official figure used by Donegal County Council is {{cvt|1134|km|0}}.<ref>{{cite web |url=https://www.donegalcoco.ie/media/donegalcountyc/planning/pdfs/viewdevelopmentplans/landscapecharacterassessmentofcountydonegal/seascapecharacterassessmentofcountydonegal/Seascape%20Character%20Assessment.pdf |title=Seascape Character Assessment of County Donegal |website=donegalcoco.ie |publisher=Donegal County Council |accessdate=13 July 2021 |archive-date=13 July 2021 |archive-url=https://web.archive.org/web/20210713103425/https://www.donegalcoco.ie/media/donegalcountyc/planning/pdfs/viewdevelopmentplans/landscapecharacterassessmentofcountydonegal/seascapecharacterassessmentofcountydonegal/Seascape%20Character%20Assessment.pdf |url-status=live}}</ref> The [[Slieve League]] cliffs are among the highest sea cliffs in Europe, while [[Malin Head]] is the most northerly point on the island of Ireland.

Two permanently inhabited islands, [[Arranmore]] and [[Tory Island]], lie off the coast, along with a large number of islands with only transient inhabitants. The 129&nbsp;km long [[River Erne]], Ireland's ninth-longest river, enters [[Donegal Bay]] near the town of [[Ballyshannon]]. The River Erne, along with other Donegal waterways, has been dammed to produce [[hydroelectricity|hydroelectric]] power. A canal linking the Erne to the [[River Shannon]] was constructed between 1846 and 1860, creating Ireland's longest navigable waterway. The project was plagued with setbacks and closed in 1870, ten years after its completion. A joint effort between the Irish and Northern Irish governments restored the canal in the late 20th century, and the [[Shannon–Erne Waterway]] reopened in 1994.{{sfn |Delany |2004 |pp=199–201}}

Historically, the eastern boundary of the kingdom of [[Tyrconnell|Tír Chonaill]] was demarcated by the [[River Foyle]]. In the 17th century, an area of land west of the Foyle was transferred to the newly established city of Derry. The Foyle still demarcated a large section of Donegal's eastern border. To the south, the Drowes River forms a 9&nbsp; km (6 miles) long natural boundary with County Leitrim.

[[File:Kinnagoe Bay, Inishowen, Co Donegal - geograph.org.uk - 83440.jpg|thumb|Kinnagoe Bay]]
Donegal has a population density of 34.2 people per square kilometre, the lowest in Ulster and the fifth lowest in Ireland. The county has an expansive network of wildlife and conservation zones, including 46 European Union designated [[Special Area of Conservation|Special Areas of Conservation]] (SACs) and 26 [[Special Protection Area]]s (SPAs), as well as 14 [[Natural Heritage Area]]s (NHAs), 74 proposed Natural Heritage Areas, 145 Irish Geological Heritage Areas (IGHs) and Ireland's second largest national park, [[Glenveagh]], which extends to over {{cvt|42000|acre|km2|0}} in northwestern Donegal.<ref>{{cite web |url=https://www.donegalcoco.ie/media/donegalcountyc/community/lcdc/App%201%20to%20LECP%20%20The%20Profile%20of%20the%20County%20February%202016.pdf |title=The Donegal Local Economic & Community Plan 2016-2022 |website=donegalcoco.ie |publisher=Donegal County Council |accessdate=23 July 2021 |archive-date=23 July 2021 |archive-url=https://web.archive.org/web/20210723010704/https://www.donegalcoco.ie/media/donegalcountyc/community/lcdc/App%201%20to%20LECP%20%20The%20Profile%20of%20the%20County%20February%202016.pdf |url-status=live}}</ref>

Owing to its scenic landscape and "''world-class wilderness''", Donegal was named [[National Geographic]]'s "Coolest place on the Planet" in 2017.<ref>{{cite news |url=https://www.irishtimes.com/life-and-style/travel/donegal-named-coolest-place-on-planet-by-national-geographic-1.2889597 |newspaper=The Irish Times |title=Donegal named coolest place on planet by National Geographic |access-date=23 July 2021 |archive-date=24 January 2021 |archive-url=https://web.archive.org/web/20210124232040/https://www.irishtimes.com/life-and-style/travel/donegal-named-coolest-place-on-planet-by-national-geographic-1.2889597 |url-status=live}}</ref> The county was also ranked the 4th best region in the world by [[Lonely Planet]]'s ''Best in Travel'' series for 2024, which called Donegal "''purely wild with a big heart''".<ref>{{Cite web|url=https://www.lonelyplanet.com/best-in-travel#donegal|title=Best in Travel 2024|last=|website=lonelyplanet.com|language=en|access-date=27 October 2023|archive-date=28 July 2023|archive-url=https://web.archive.org/web/20230728073433/https://www.lonelyplanet.com/best-in-travel#donegal|url-status=live}}</ref>

The forested area in the county extends to {{cvt|55534|ha|0}}, the 4th highest total forest cover in Ireland.<ref>{{cite web |url=https://www.gov.ie/en/publication/65294-irelands-national-forest-inventory/ |title=National Forestry Inventory, Third Cycle 2017 |work=DAFM |date=17 November 2020 |access-date=23 July 2021 |archive-date=20 June 2021 |archive-url=https://web.archive.org/web/20210620124029/https://www.gov.ie/en/publication/65294-irelands-national-forest-inventory/ |url-status=live}}</ref> Historic deforestation left Donegal devoid of forest cover by 1900. Much of the county's forests are commercial timber plantations which were initially established in the 1930s as a way to create rural employment in areas with poor agricultural land and high rates of emigration.<ref>O'Carroll, pp. 22-23</ref> The county contains extensive tracts of [[blanket bog]] which are concentrated in western and upland regions. Blanket bog covers an area of {{cvt|148656|ha|0}}, or roughly 30 percent of the entire county.<ref>Douglas et al., pp. 27</ref>

===Flora and fauna===
[[File:Aquila chrysaetos La Canada 2012-01-14.jpg|thumb|right|210px|[[Golden eagle]] (''Aquila chrysaetos'') ]]

Donegal has a wide variety of habitats, and over half of Ireland's plant and animal species can be found within the county. Approximately 11.4 per cent of the county is covered in forest, which is about average nationally. Forest cover is not evenly spread across the county and some areas, such as [[Pettigo]] and around [[Lough Derg, County Donegal|Lough Derg]], are very heavily forested, while more exposed coastal and upland areas are virtually barren. Around 65 per cent of Donegal's forests are publicly owned. 
*The typical native tree species found in Donegal are [[Scots pine]], [[Populus tremula|aspen poplar]], [[birch]], [[Corylus avellana|hazel]] and [[Quercus robur|oak]]. Other common trees include [[Sitka spruce]], [[Rowan|mountain ash]], [[Acer pseudoplatanus|sycamore]], [[Larix decidua|European larch]] and [[Aesculus hippocastanum|horse-chestnut]].<ref>{{Cite web |url=http://www.askaboutireland.ie/enfo/irelands-environment/county-focus/donegal/glenveagh-national-park/wildlife/ |title=Trees & Plants - Glenveagh National Park |website=askaboutireland.ie |access-date=21 July 2021 |archive-date=20 July 2021 |archive-url=https://web.archive.org/web/20210720233445/http://www.askaboutireland.ie/enfo/irelands-environment/county-focus/donegal/glenveagh-national-park/wildlife/ |url-status=live}}</ref>
*Many species of terrestrial and flying mammals live in the county, including [[Irish hare]]s, [[European hare|brown hare]]s, [[red deer]], [[sika deer]], [[Leisler's Bat|Irish bats]], [[Common pipistrelle|common pipistrelle bats]], [[Soprano pipistrelle|soprano pipistrelle bats]], [[brown long-eared bat]]s, [[whiskered bat]]s, [[Daubenton's bat]]s, [[Natterer's bat]]s, [[American mink]], [[Eurasian pygmy shrew|pygmy shrews]], [[European rabbit|rabbits]], [[European pine marten|pine martens]], [[stoat]]s, [[European badger|badgers]], [[red squirrel]]s, [[Eastern gray squirrel|gray squirrels]], [[Wood mouse|wood mice]], [[House mouse|house mice]], [[brown rat]]s, [[Eurasian otter|otters]], [[red fox]]es, [[European hedgehog|hedgehogs]] and [[feral goat]]s.<ref name="Donegal CoCo., pp. 89">Donegal CoCo., pp. 89</ref>
*Marine mammals include [[Harbor seal|harbour seals]], [[grey seal]]s, [[humpback whale]]s, [[orca]]s, [[pilot whale]]s, [[fin whale]]s, [[minke whale]]s, [[sperm whale]]s, [[Cuvier's beaked whale]]s, [[common dolphin]]s, [[bottlenose dolphin]]s, [[Atlantic white-sided dolphin]]s, [[white-beaked dolphin]]s, [[striped dolphin]]s, [[Risso's dolphin]]s and (very rarely) [[walrus]]es.<ref name="Donegal CoCo., pp. 89"/>
*Notable bird species include [[Barnacle goose|barnacle geese]], [[corn crake]]s, [[northern lapwing]]s (Ireland's [[List of national birds|national bird]]), [[grey heron]]s, [[Long-eared owl]]s, [[golden eagle]]s, [[Western barn owl|barn owl]]s, [[yellowhammer]]s, [[European storm petrel|storm petrels]], [[Parasitic jaeger|Arctic skuas]], [[Eurasian wren|wrens]], [[European goldfinch|goldfinches]], [[Atlantic puffin]]s, [[razorbill]]s, [[Common raven|ravens]], [[Eurasian curlew|curlews]] and [[Common redshank|redshanks]].<ref>Donegal CoCo., pp. 85-88</ref>
Despite its northerly latitude and geographic isolation, Donegal also hosts two species of amphibian ([[common frog]] & [[smooth newt]]) and two reptile species ([[Leatherback turtle]] and [[viviparous lizard]]).<ref>Donegal CoCo., pp. 84</ref>

The native [[Irish red deer]] in Donegal went extinct around 1860 and were re-introduced in the 1890s. Due to interbreeding, most of the deer in the county are now a Sika-Red deer hybrid. The Wild Ireland wildlife park near [[Burnfoot, County Donegal|Burnfoot]] showcases some of Donegal's historic animal species that were hunted to extinction, including [[brown bear]]s, [[Eurasian Lynx|lynxes]] and [[Gray wolf|gray wolves]].<ref>{{Cite web |url=https://www.rte.ie/news/ulster/2019/1024/1085427-bears-wolves/ |title=Bears, wolves, lynx and monkeys at Donegal wildlife sanctuary |website=rte.ie |date=24 October 2019 |access-date=21 July 2021 |last1=Magnier |first1=Eileen |archive-date=20 July 2021 |archive-url=https://web.archive.org/web/20210720232535/https://www.rte.ie/news/ulster/2019/1024/1085427-bears-wolves/ |url-status=live}}</ref> In 2001, the golden eagle was re-introduced into [[Glenveagh National Park]] and is currently Ireland's only breeding population.<ref>{{Cite web |url=https://www.glenveaghnationalpark.ie/golden-eagle-pair-spotted-in-glenveagh-national-park/ |title=Golden Eagle pair spotted in Glenveagh National Park |website=glenveaghnationalpark.ie |access-date=21 July 2021 |archive-date=20 July 2021 |archive-url=https://web.archive.org/web/20210720232432/https://www.glenveaghnationalpark.ie/golden-eagle-pair-spotted-in-glenveagh-national-park/ |url-status=live}}</ref>

A survey of the macroscopic marine [[algae]] of County Donegal was published in 2003.<ref>Morton, O. 2003. The marine macroalgae of County Donegal, Ireland. ''Bulletin of Irish biogeoghical Society.'' 27: 3 – 164</ref> The survey was compiled using the algal records held in the [[herbarium|herbaria]] of the following institutions: the [[Ulster Museum]], [[Belfast]]; [[Trinity College Dublin]]; [[NUI Galway]], and the [[Natural History Museum, London|Natural History Museum]], London.
Records of flowering plants include ''[[Dactylorhiza purpurella]]'' (Stephenson and Stephenson) Soó.<ref>Ennis, T. 2014. The occurrence of ''Dactylorhiza purpurella'' (T.Stephenson and T.S.Stephenson) Soó ''Irish Naturalists' Journal.'' '''33''': 128</ref>

===Climate===
[[File:Errigal Snow.jpg|thumb|Snow atop [[Errigal]]]]
The majority of Donegal has a [[temperate]] [[oceanic climate|oceanic]] climate ([[Köppen climate classification]]: Cfb), with upland areas in the [[Derryveagh Mountains|Derryveagh]] and [[Blue Stack Mountains|Blue Stack]] ranges classified as [[Oceanic climate#Subpolar variety (Cfc, Cwc)|oceanic subpolar]] (Köppen climate classification: Cfc).<ref name="met.ie">{{Cite web |url=https://www.met.ie/climate/weather-extreme-records |title=Extreme weather records for Ireland |website=met.ie |access-date=21 July 2021 |archive-date=21 March 2021 |archive-url=https://web.archive.org/web/20210321232347/https://www.met.ie/climate/weather-extreme-records |url-status=live}}</ref> The county's climate is heavily influenced by the [[North Atlantic Current]]. Due to the topography of western Donegal, it receives [[orographic]] rainfall, where the air is forced to rise on contact with its mountainous coastline and subsequently cools and [[Condensation|condenses]], forming clouds. The mountains of Donegal are among the cloudiest places in Ireland,<ref>{{Cite web |url=https://www.met.ie/climate/what-we-measure/sunshine |title=Climate of Ireland - Sunshine |website=met.ie |access-date=21 July 2021 |archive-date=21 July 2021 |archive-url=https://web.archive.org/web/20210721150334/https://www.met.ie/climate/what-we-measure/sunshine |url-status=live}}</ref> and northern Donegal is the windiest. Irish monthly record wind speeds for March, June, July, September, November and December have all been set at [[Malin Head]]. The highest wind speed ever recorded in Donegal was 181&nbsp;km/h (112&nbsp;mph) on 16 September 1961, during [[Hurricane Debbie (1961)|Hurricane Debbie]].<ref name="met.ie"/>

The [[Atlantic Ocean]] has a significant cooling effect and, due to the county's long, thin shape and punctuated coastline, nowhere in Donegal is particularly far from the ocean, giving it a generally cooler climate that is more similar to western Scotland than the rest of Ireland. The average maximum temperature in July at Malin Head is just {{cvt|16.8|°C|0}}.<ref>{{Cite web |url=https://www.met.ie/climate-ireland/1981-2010/malin.html |title=Malin Head 1981–2010 averages |website=met.ie |access-date=21 July 2021 |archive-date=21 July 2021 |archive-url=https://web.archive.org/web/20210721150342/https://www.met.ie/climate-ireland/1981-2010/malin.html |url-status=live}}</ref> However, due to its exposed coastal location, the climate at Malin Head is not representative of most of the county. Winds are much lighter in the county's interior and temperatures are cooler in the winter and warmer in the summer. Annual rainfall in the county ranges from around {{cvt|850|mm|0}} in the lowlands of north-eastern Donegal to over {{cvt|2000|mm|0}} in western mountainous areas.<ref>{{Cite web |url=https://www.met.ie/climate/what-we-measure/rainfall |title=Climate of Ireland - Rainfall |website=met.ie |access-date=21 July 2021 |archive-date=21 July 2021 |archive-url=https://web.archive.org/web/20210721150345/https://www.met.ie/climate/what-we-measure/rainfall |url-status=live}}</ref> Precipitation exceeding 1&nbsp;mm (0.04&nbsp;in) will fall across all areas of Donegal on over 150 days per year.

While the prevailing wind direction in Ireland is south-westerly, which brings warm, moist air from the [[Gulf of Mexico]], a low-pressure [[Polar front]] regularly passes to the northwest of the island, bringing cold and unsettled weather to the region.<ref>{{Cite web |url=https://www.met.ie/climate/climate-of-ireland |title=Climate of Ireland - Polar front |website=met.ie |access-date=21 July 2021 |archive-date=25 June 2021 |archive-url=https://web.archive.org/web/20210625114614/https://www.met.ie/climate/climate-of-ireland |url-status=live}}</ref> The upland areas of Donegal will reliably receive some covering of snow every year. In lowland areas, snow - while still relatively infrequent - is more common than in the rest of Ireland. Despite its coastal location, Malin Head records an average of 20 days of snowfall per year. In contrast [[Valentia Island]], a similarly placed coastal station in the southwest of Ireland records just 3.<ref>{{Cite web |url=http://www.met.ie/climate-ireland/1981-2010/valentia.html |title=Valentia 1981–2010 averages |website=met.ie |access-date=21 July 2021 |archive-date=21 March 2021 |archive-url=https://web.archive.org/web/20210321232340/https://www.met.ie/climate-ireland/1981-2010/valentia.html |url-status=live}}</ref>

===Geology and terrain===
[[File:Donegalmap.jpg|thumb|Topographic map of County Donegal]]
[[Image:Glenveagh Valley (2009).jpg|thumb|left|Glenveagh Valley]]
Donegal can be divided into six main geological subdivisions.<ref>GSI., pp. 29</ref> Of these, the most expansive sections are the [[Lower Carboniferous]] limestones and sandstones of south Donegal, the [[Devonian]] granite of the [[Donegal batholith]], which extends for about 75&nbsp; km northeast to southwest from [[Ardara, County Donegal|Ardara]] to [[Fanad]] Head, and quartzo-feldspathic [[Dalradian]] rocks from the [[Precambrian]] era, which cover much of the rest of the county. The geology of Donegal is very similar to that of [[County Mayo]], and both counties are located within the [[Grampian Mountains|Grampian]] [[Terrane]]. The oldest rocks in Ireland are a [[Granite|granitic]] [[gneiss]] found on the island of [[Inishtrahull]], located ca. {{cvt|10|km|mi}} north-east of Malin Head. They are 1.78 billion years old, making them [[Paleoproterozoic]] in age.<ref name="Muir">{{cite journal |last=Muir |first=R.J. |author2=Fitches W.R. |author3=Maltman A.J. |year=1994 |title=The Rhinns Complex: Proterozoic basement on Islay and Colonsay, Inner Hebrides, Scotland, and on Inishtrahull, NW Ireland |journal=Transactions of the Royal Society of Edinburgh: Earth Sciences |volume=85 |issue=1 |pages=77–90 |url=http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8344451 |access-date=15 September 2012 |doi=10.1017/s0263593300006313 |s2cid=131108674 |archive-date=22 July 2015 |archive-url=https://web.archive.org/web/20150722123641/http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8344451 |url-status=live}}</ref> The oldest rocks on mainland Donegal are a quartzo-feldspathic paragneiss found around Lough Derg, which have been dated to 1.713 billion years ago.<ref>{{Cite web |url=https://www.gsi.ie/documents/Geoschol_Donegal_Geology.pdf |title=Geology of County Donegal |website=gsi.ie |access-date=22 July 2021 |archive-date=18 December 2017 |archive-url=https://web.archive.org/web/20171218114131/https://www.gsi.ie/documents/Geoschol_Donegal_Geology.pdf |url-status=live}}</ref>

Donegal is the most seismically active part of Ireland. The [[Great Glen Fault|Leenan Fault]] is a large [[Fault (geology)#Strike-slip faults|strike-slip fault]] that bisects the county from Lough Swilly to Donegal Bay, and dozens of tremors have been recorded along the fault since the late 19th century, although none have been larger than a magnitude 3 on the [[Richter magnitude scale|Richter scale]].<ref>{{Cite web |url=https://www.irishtimes.com/culture/heritage/why-does-donegal-get-a-disproportionate-number-of-irish-earthquakes-1.3854663 |title=Why does Donegal get a disproportionate number of Irish earthquakes? |website=irishtimes.com |access-date=22 July 2021 |archive-date=24 July 2021 |archive-url=https://web.archive.org/web/20210724135745/https://www.irishtimes.com/culture/heritage/why-does-donegal-get-a-disproportionate-number-of-irish-earthquakes-1.3854663 |url-status=live}}</ref><ref>{{Cite news |url=https://www.bbc.com/news/world-europe-48102567 |title=Earthquake close to Irish border in County Donegal |work=BBC News |date=30 April 2019 |access-date=22 July 2021 |archive-date=21 July 2021 |archive-url=https://web.archive.org/web/20210721202816/https://www.bbc.com/news/world-europe-48102567 |url-status=live}}</ref>

The county's landscape was carved out by glaciation at the end of the [[Pleistocene]] and the subsequent [[Holocene glacial retreat|retreat]] during the early [[Holocene]]. Donegal contains one of Ireland's three glacial [[fjord]]s (or [[fjard]]s) at [[Lough Swilly]], the others being [[Carlingford Lough]] and [[Killary Harbour]].{{sfn|Dundurn|2000|p=4}} Lough Swilly is the county's largest inlet and forms the western boundary of the [[Inishowen Peninsula]]. The thick ice sheet that once covered the region carved out deep basins in the Donegal uplands and many [[Tarn (lake)|tarns]] or corrie lakes developed in these depressions after the ice had melted, including Lough Maam below [[Slieve Snaght]] and Lough Feeane under [[Aghla More]]. Larger glacial lakes formed in the county's distinctive [[U-shaped valley]]s, such as [[Lough Beagh]] and [[Gartan Lough]] in [[Glenveagh]], and [[Dunlewey Lough]] and [[Lough Nacung Upper]] in the [[Poisoned Glen]]. Valleys such as these were the last areas to retain glaciers as temperatures rose.<ref>GSI., pp. 37</ref>

As the ice sheet thinned, topography became the dominant force driving the direction of ice and meltwater flow.<ref>GSI., pp. 38</ref> Erosion by glacial meltwater carved out large channels in southern Donegal which directed water and sediment to [[outwash fan]]s in Donegal Bay. The area south of Donegal town, where the [[River Eske]] flows into the bay, is an example of one of these outwash areas. Sea levels in the area began to stabilise around 5,000 years ago, and the balance of erosion and deposition along Donegal's coastline resulted in the development of many sandy beaches and [[Spit (landform)|spits]] interspersed with jagged sea cliffs.<ref>GSI., pp. 36</ref>