The geography of Ireland describes an island in northwest Europe in the north Atlantic Ocean. The main geographical features of Ireland include low central plains surrounded by a ring of coastal mountains. The highest peak is Carrauntoohil ( ), which is above sea level. The western coastline is rugged, with many islands, peninsulas, headlands and bays. The island is bisected by the River Shannon, which at with a estuary is the longest river in Ireland and flows south from County Cavan in Ulster to meet the Atlantic just south of Limerick. There are a number of sizeable lakes along Ireland's rivers, of which Lough Neagh is the largest.

Politically, the island consists of the state, Ireland, with jurisdiction over about five sixths of the island; and Northern Ireland, a constituent country of the United Kingdom, with jurisdiction over the remaining sixth. Located west of the island of Great Britain, it is located at approximately . It has a total area of . It is separated from Great Britain by the Irish Sea and from mainland Europe by the Celtic Sea.

Geological development

The oldest known Irish rock is about 1.7 billion years old and is found on Inishtrahull Island off the coast of County Donegal. In other parts of Donegal, scientists have discovered rocks that began life as glacial deposits, demonstrating that at this early period, part of what was to become Ireland was in the grip of an ice age. However, because of the effects of later upheavals, it is almost impossible to sequence these early rock layers correctly.

About 600 million years ago, at the end of the Precambrian era, the Irish landmass was divided in two, with one half on the western side of the Iapetus Ocean and the other at the eastern side, both at about the latitude that of around 80° South, close to what is now northwest Africa. From the evidence of fossils found at Bray Head in County Wicklow, Ireland was below sea level at this time.

Over the next 50 million years, these two parts drifted towards each other, eventually uniting about 440 million years ago. Fossils discovered near Clogher Head, County Louth, show the coming together of shoreline fauna from both sides of the original dividing ocean. The mountains of northwest Ireland were formed during the collision, as was the granite that is found in locations in Donegal and Wicklow. The Irish landmass was now above sea level and lying near the equator, and fossil traces of land-based life forms survive from this period. These include fossilised trees from Kiltorcan, County Kilkenny, widespread bony fish and freshwater mussel fossils and the footprints of a four-footed amphibian preserved in slate on Valentia Island, County Kerry. Old Red Sandstone also formed at this time.

Between 400 million and 300 million years ago, northwest Europe – including Ireland – sank beneath a warm, calcium-rich sea. Great coral reefs formed in these waters, eventually creating the limestone that still makes up about 65 per cent of the rock mantle of the island. As the waters receded, tropical forests and swamps flourished. The resulting vegetable debris eventually formed coal, most of which was later eroded. This period, known as the Carboniferous era, ended with further tectonic movement which saw Ireland drift further northward. The resulting pressure created those Irish mountain and hill ranges that run in a northeast to southwest direction.

By 250 million years ago, Ireland was at the latitude of present-day Egypt and had a desert climate. It was at this time that most of the coal and sandstone were eroded. The thinner layers of limestone in the south of the country were also partially affected by this erosion. The limestone that was exposed by the disappearance of its sandstone mantle was affected by carbon dioxide and other factors resulting in a karstic landscape that can still be seen in the Burren in County Clare. Shortly after this period, organic debris in the seas around Ireland began to form the natural gas and petroleum deposits that now play an important role in the economy of Ireland. Then, about 150 million years ago, Ireland was again submerged, this time in a chalky sea that resulted in the formation of chalk over large parts of the surface. Traces of this survive under the basalt lava that is found in parts of the north.

About 65 million years ago, the volcanic activity that formed this lava began. The Mourne Mountains and other mountains in the northern part of the island formed as a result of this activity. Climatic conditions at this time were warm and vegetation thrived. Vegetable debris in the Antrim depression formed deposits of brown coal or lignite which remain untouched down to the present time. The warm conditions produced high rainfall that accelerated processes of erosion and the formation of karstic landscape forms.

By 25 million years ago, Ireland was close to assuming its present position. The long period of erosion had resulted in considerable soil formation and most of the rock mantle was covered. In areas with good drainage, the covering consisted of brown or grey soil, while in poorly drained areas the black clay tended to dominate. As the climate cooled, soil formation slowed down, and a flora and fauna that would, millions of years later, be familiar to the first human inhabitants began to emerge. By about three million years ago, the present landscape of Ireland had more or less formed.

Since about 1.7 million years ago, the earth has been in the grip of a cycle of warm and cold stages and these have, inevitably, affected Ireland. The earliest evidence we have for this effect comes from the period known as the Ballylinian Warm Stage, some half a million years ago. At this time, most of what are now considered to be native Irish trees were already established on the island. The action of the ice during the cold stages was the major factor in bringing the Irish landscape to its current form.

Obvious impacts of the ice on the landscape include the formation of glacial valleys such as Glendalough in Wicklow and of corrie, or glacial lakes. The depositing of mounds of debris under the melting ice created drumlins, a common feature of the landscape across the north midlands. Streams also formed under the ice and the material deposited by these formed eskers (Irish eiscir). The greatest of these, the Esker Riada, divides the northern and southern halves of the island and its ridge once served as the main highway connecting the east and west coasts. About one half of the coastline consists of a low lying dune pasture land known as Machair.

Rocks and soil types

The large central lowland is of limestone covered with glacial deposits of clay and sand, with widespread bogs and lakes. The Bog of Allen is one of the largest bogs. The coastal mountains vary greatly in geological structure. In the south, the mountains are composed of old red sandstone with limestone river valleys. In Galway, Mayo, Donegal, Down and Wicklow, the mountains are mainly granite, while much of the northeast of the country is a basalt plateau. An area of particular note is the Giant's Causeway, in Antrim, a mainly basalt formation caused by volcanic activity between 50–60 million years ago. The basalts were originally part of the great Thulean Plateau formed during the Paleogene period.

The soils of the north and west tend to be poorly drained peats and gley, including peaty podzols. In contrast, in the south and east the soils are free-draining brown earths and brown and grey-brown podzols. This is reflected in the rainfall distribution on the island, with the poorly drained regions being those with the highest rainfalls.

An unusual environment is present in north County Clare, in an area known as the Burren. This karst-like landscape consists of limestone bedrock, with little or no soil in the inner-most areas. There are numerous sinkholes, where surface water disappears through the porous rock surface, and extensive cave systems have been formed in some areas. The Pol an Ionain cave, near Doolin, is the site of one of the world's longest known free-hanging stalactites.

Mountain ranges

Ireland consists of a mostly flat low-lying area in the midlands, ringed by mountain ranges such as (beginning in County Kerry and working counter-clockwise) the Macgillycuddy's Reeks, Comeragh Mountains, Blackstairs Mountains, Wicklow Mountains, the Mournes, Glens of Antrim, Sperrin Mountains, Bluestack Mountains, Derryveagh Mountains, Ox Mountains, Nephinbeg Mountains and the Twelve Bens/Maumturks group. Some mountain ranges are further inland in the south of Ireland, such as the Galtee Mountains, the highest inland range, Silvermines and Slieve Bloom Mountains. The highest peak is Carrauntoohil, 1,038 m (3,405 ft) high, is in the Macgillycuddy's Reeks, a range of glacier-carved sandstone mountains in County Kerry, in the southwest of the island. The mountains are not high – only three peaks are over 1,000 m (3,281 ft) and another 457 exceed 500 m (1,640 ft).

Rivers and lakes

The main river in Ireland is the River Shannon, 386 km (240 miles), the longest river in either Ireland or Great Britain, which separates the boggy midlands of Ireland from the West of Ireland. The river develops into three lakes along its course, Lough Allen, Lough Ree, and Lough Derg. Of these, Lough Derg is the largest. The River Shannon enters the Atlantic Ocean after Limerick city at the Shannon Estuary. Other major rivers include the River Liffey, River Lee, River Blackwater, River Nore, River Suir, River Barrow, River Erne, and River Boyne. (See the list of rivers in Ireland.)

Lough Neagh, in Ulster, is the largest lake in Ireland and the UK. Legend has it that a giant, Fionn mac Cumhail, was fighting with another in Scotland, and enraged, scooped out a lump of earth, which he threw. It fell into the Irish Sea, creating the Isle of Man, while the hole filled up with water to become Lough Neagh. Other large lakes include Lough Erne and Lough Corrib.

Inlets

Beginning with County Donegal, Lough Swilly separates one side of the Inishowen peninsula. Lough Foyle on the other side, is one of Ireland's larger inlets, situated between County Donegal and County Londonderry. Further round the coast is Belfast Lough, between County Antrim and County Down. Also in County Down is Strangford Lough, actually an inlet partially separating the Ards peninsula from the mainland. Further down the coast, Carlingford Lough is situated between Down and County Louth.

Dublin Bay is the next sizable inlet, while the eastern coast of Ireland is mostly uniform until Wexford Harbour at the mouth of the River Slaney. On the southern coast, Waterford Harbour is situated at the mouth of the River Suir (into which the other two of the Three Sisters (River Nore and River Barrow) flow). The next major inlet is Cork Harbour, at the mouth of the River Lee, in which Great Island is situated.

Dunmanus Bay, Bantry Bay, Kenmare estuary and Dingle Bay are all inlets between the peninsulas of County Kerry. North of these is the Shannon estuary. Between north County Clare and County Galway is Galway Bay. Clew Bay is located on the coast of County Mayo, south of Achill Island, while Blacksod Bay is north of the island. Killala Bay is on the north coast of Mayo. Donegal Bay is a major inlet between County Donegal and County Sligo.

Headlands

Malin Head is the most northerly point in Ireland, while Mizen Head is one of the most southern points, hence the term "Malin head to Mizen head" (or the reverse) is used for anything applying to the island of Ireland as a whole. Carnsore Point is another extreme point of Ireland, being the southeasternmost point of Ireland. Further along the coast is Hook Head while the Old Head of Kinsale in is one of many headlands along the south coast of Ireland.

Loop Head is the headland at which County Clare comes to a point on the west coast of Ireland, with the Atlantic on the north, and further inland on the south, the Shannon estuary. Hag's Head is another headland further up Clare's north/western coastline, with the Cliffs of Moher along the coastline north of the point.

Erris Head is the northwesternmost point of Connacht.

Islands and peninsulas

Achill Island, in the northwest, is the largest island off Ireland's coast. The island is inhabited, and is connected to the mainland by a bridge. Some of the next largest islands are the Aran Islands, off the coast of southern Connacht, host to an Irish-speaking community, or Gaeltacht. Valentia Island off the Iveragh peninsula is also one of Ireland's larger islands, and is relatively settled, as well as being connected by a bridge at its southeastern end. Omey Island, off the coast of Connemara is a tidal island.

Some of the best-known peninsulas in Ireland are in County Kerry; the Dingle peninsula, the aforementioned Iveragh peninsula and the Beara peninsula. The Ards peninsula is one of the larger peninsulas outside Kerry. The Inishowen peninsula in County Donegal includes Ireland's most northerly point, Malin Head and several important towns including Buncrana on Lough Swilly, Carndonagh and Moville on Lough Foyle. Ireland's most northerly land feature is Inishtrahull island, off Malin Head. Rockall Island may deserve this honour but its status is disputed, being claimed by the United Kingdom, Republic of Ireland, Denmark (for the Faroe Islands) and Iceland. The most southerly point is the Fastnet Rock.

Climate

Ireland's climate is temperate, though significantly warmer than almost all other locations at similar latitude, such as Poland (on the continent) or Newfoundland (on the opposite edge of the Atlantic), due to the warming influence of the North Atlantic drift. The prevailing wind blows from the southwest, breaking on the high mountains of the west coast. Rainfall is therefore a particularly prominent part of western Irish life, with Valentia Island, off the west coast of County Kerry, getting almost twice as much annual rainfall as Dublin on the east (1400 mm vs. 762 mm). Across the country, about 60% of the annual rainfall occurs between August and January.

January and February are the coldest months of the year, and mean daily air temperatures fall between 4 and 7 °C during these months. July and August are the warmest, with a range of 14 to 16 °C. The sunniest months are May and June, with an average of five to seven hours sunshine per day. Though extreme weather events in Ireland are comparatively rare when compared with other countries in the European Continent, they do occur. Explosive Atlantic depressions, occurring mainly in the months of December, January and February, can occasionally bring winds of up to 160 km/ph (100 mph) to Western coastal counties; while the summer months, and particularly around late July/early August, sudden and violent thunderstorms can develop, more especially, but not exclusively, across midland and western areas of the country.

The table shows mean climate figures for the Dublin Airport weather station over a thirty-year period. Climate statistics based on the counties of Northern Ireland vary slightly but are not significantly different.

Dublin Airport weather station statistics from 1961 to 1990
Factor	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Year
Mean daily max temp (°C)	7.6	7.5	9.5	11.4	14.2	17.2	18.9	18.6	16.6	13.7	9.8	8.4	12.8
Mean daily min temp (°C)	2.5	2.5	3.1	4.4	6.8	9.6	11.4	11.1	9.6	7.6	4.2	3.4	6.0
Mean daily sunshine (h)	1.8	2.5	3.6	5.2	6.1	6.0	5.4	5.1	4.3	3.1	2.4	1.7	3.9
Mean monthly rain (mm)	69.4	50.4	53.8	50.7	55.1	56.0	49.9	70.5	66.7	69.7	64.7	75.6	732.7

Political and human geography

Ireland is divided into four provinces, Connacht, Leinster, Munster and Ulster, and 32 counties. Six of the nine Ulster counties form Northern Ireland and the other 26 form the state, Ireland. The map shows the county boundaries for all 32 counties.

(republic of) Ireland Dublin Wicklow Wexford Carlow Kildare Meath Louth Monaghan Cavan Longford Westmeath Offaly Laois Kilkenny Waterford Cork

Kerry Limerick Tipperary Clare Galway Mayo Roscommon Sligo Leitrim Donegal Northern Ireland Fermanagh Tyrone Londonderry Antrim Down Armagh

From an administrative viewpoint, 20 of the counties in the republic are units of local government. The other six have more than one local authority area, producing a total of 34 county-level authorities. Tipperary has two ridings, North Tipperary and South Tipperary, originally established in 1838 and renamed in 2001. The cities of Dublin, Cork, Limerick, Galway and Waterford have city councils and are administered separately from the counties bearing those names. The remaining part of County Dublin is split into Dun Laoghaire-Rathdown, Fingal, and South Dublin.

Electoral areas in Ireland (the state), called constituencies in accordance with Irish law, mostly follow county boundaries. Maintaining links to the county system is a mandatory consideration in the re-organisation of constituency boundaries..

In Northern Ireland, a major re-organisation of local government in 1973 replaced the six traditional counties and two county boroughs (Belfast and Derry) by 26 single-tier districts, which, apart from Fermanagh cross the traditional county boundaries. The six counties and two county-boroughs remain in use for purposes such as Lieutenancy. In November 2005, proposals were announced which would see the number of local authorities reduced to seven.The island's total population of approximately 6 million people is concentrated on the east coast, particularly in Dublin and Belfast and their surrounding areas.

Natural resources

Bogs

Ireland has 12,000 km² (4,633 miles²) of bogland, consisting of two distinct types, blanket bogs and raised bogs. Blanket bogs are the more widespread of the two types. They are essentially a product of human activity aided by the moist Irish climate. Blanket bogs formed on sites where Neolithic farmers cleared trees for farming. As the land so cleared fell into disuse, the soil began to leach and become more acidic, producing a suitable environment for the growth of heather and rushes. The debris from these plants accumulated and a layer of peat formed.

Raised bogs are most common in the Shannon basin. They formed when depressions left behind after the ice age filled with water to form lakes. Debris from reeds in these lakes formed a layer at the bottom of the water. This eventually choked the lakes and raised above the surface, forming raised bogs.

Since the 17th century, peat has been cut for fuel for domestic heating and cooking and it is called turf when so used. The process accelerated as commercial exploitation of bogs grew. In the 1940s, machines for cutting turf were introduced and larger-scale exploitation became possible. In the Republic, this became the responsibility of a semi-state company called Bord na Móna. In addition to domestic uses, commercially extracted turf is used in a number of industries, especially electricity generation.

In recent years, the high level of bog being destroyed by cutting has raised environmental concerns. The problem is particularly acute for raised bogs as they yield a higher-grade fuel than blanket bogs. Plans are now in place in both the Republic and Northern Ireland to conserve most of the remaining raised bogs on the island.

Oil, natural gas and minerals

Offshore exploration for natural gas began in 1970. The first major discovery was the Kinsale Head gas field in 1971. Next was the smaller Ballycotton gas field in 1989, and the Corrib gas field in 1996. Exploitation of the Corrib project has yet to get off the ground because the controversial proposal to refine the gas onshore, rather than at sea has been met with widespread opposition. Gas from these fields is pumped ashore and used for both domestic and industrial purposes. The Helvick oil field, estimated to contain over of oil, is another recent discovery. Ireland is the largest European producer of zinc with three operating zinc-lead mine at Navan, Galmoy and Lisheen. Other mineral deposits with actual or potential commercial value include gold, silver, gypsum, talc, calcite, dolomite, roofing slate, limestone aggregate, building stone, sand and gravel.

In May 2007 the Department of Communications, Marine and Natural Resources (now replaced by the Department of Communications, Energy and Natural Resources) reported that there may be volumes over of petroleum and of natural gas in Irish waters - worth trillions of Euro, if true. The minimum 'guaranteed' amount of oil in the Irish Atlantic waters is , worth over €450 billion. There are also areas of petroleum and natural gas on shore, for example the Lough Allen basin, with of gas and of oil, valued at €74.4 billion. Already some fields are being exploited, such as the Spanish Point field, with of gas and of oil, valued at €19.6 billion. The Corrib Basin is also quite large, worth anything up to €87 billion, while the Dunquin gas field contains of natural gas and of petroleum.

See also

• Geography of the Republic of Ireland
• Geography of the United Kingdom

References

1. Hill, Jon & Davis, Katie. " Precambrian History of England and Wales". GeologyRocks.com, November, 2007. Retrieved on 23 January 2008.
2. " Northern Ireland - Living World". bbc.co.uk. Retrieved on 23 January 2008.
3. Brittle tectonism in relation to the Palaeogene evolution of the Thulean/NE Atlantic domain: a study in Ulster Retrieved on 10 November 2007
4. " Major reform of local government". bbc.co.ik, 22 November 2005. Retrieved on 23 January 2007.
5. Shannon, Corcoran & Haughton (2001), The petroleum exploration of Ireland's offshore basins: introduction (Geological Society, London Lyell Collection—Special Publications, p 2

Bibliography

Print

• Mitchell, Frank and Ryan, Michael. Reading the Irish landscape (1998). ISBN 1-86059-055-1
• Whittow, J. B. Geography and Scenery in Ireland (Penguin Books 1974)

Online

• Abbot, Patrick. Ireland's Peat Bogs. Retrieved on 23 January 2008.
• Irish Department of Foreign Affairs: Facts about Ireland.
• Ireland – The World Factbook. Central Intelligence Agency. Retrieved on 23 January 2008.
• OnlineWeather.com – climate details for Ireland. Retrieved on 23 January 2008.

External links

• Ireland Geography Guide
• OSI FAQ – Lists of the longest, highest and other statistics
• A discussion on RTÉ Radio One's science show Quantum Leap about the quality of GPS mapping in Ireland is available here. The discussion starts 8mins 17sec into the show. It was aired on 18 Jan 2007 Requires Real player.

Maps from

• irelandstory.com
• Geography Ireland