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Geography of Ireland

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   Ireland is sometimes known as the "Emerald Isle" because of its green
   scenery.
   Enlarge
   Ireland is sometimes known as the "Emerald Isle" because of its green
   scenery.

   The geography of Ireland describes an island in northwest Europe in the
   North Atlantic Ocean. The ocean is responsible for the rugged western
   coastline, along which are many islands, peninsulas, and headlands. The
   main geographical features of Ireland are low central plains surrounded
   by a ring of coastal mountains. The highest peak is Carrauntuohill (
   Irish: Corrán Tuathail), which is 1041  m (3414  ft). There are a
   number of sizable lakes along Ireland's rivers, with Lough Neagh the
   largest in either Britain or Ireland. The island is bisected by the
   River Shannon, at 259  km (161  miles) with a 113 km (70 miles) estuary
   the longest river in Ireland which flows south from County Cavan in the
   north to meet the Atlantic just south of Limerick.

   The island of Ireland consists politically of the Republic of Ireland
   and Northern Ireland. Located west of the island of Great Britain, it
   is located at approximately 53° N 8° W. It has a total area of 84,079
   km² (32,477  mile²). Ireland is separated from Britain by the Irish Sea
   and from mainland Europe by the Celtic Sea.

Physical geography

Geological development

   Slieve League in Donegal is a fine example of early Irish rock
   formation.
   Enlarge
   Slieve League in Donegal is a fine example of early Irish rock
   formation.

   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 South Africa currently occupies. 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 plate 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.
   Karstic landscape in the Burren
   Enlarge
   Karstic landscape in the Burren

   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 gas and oil deposits that now play an important role
   in the island's economy. 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 corries, 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.

Rocks and soil types

   Layers of siltstone, shale and sandstone can be seen in the Cliffs of
   Moher, near Doolin in County Clare
   Layers of siltstone, shale and sandstone can be seen in the Cliffs of
   Moher, near Doolin in County Clare

   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
   north-east of the country is a basalt plateau. An area of particular
   note is the Giant's Causeway, in County Antrim, a mainly basalt
   formation.

   The soils of the north and west tend to be poorly drained peats and
   gleys, 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 sink-holes, where surface water disappears through the porous
   rock surface, and extensive cave systems have been formed in some
   areas.
   Mountains, lakes, rivers and other physical features of Ireland are
   shown on this map (large version).
   Mountains, lakes, rivers and other physical features of Ireland are
   shown on this map ( large version).

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, Blackstair 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, Silvermines and Slieve Bloom
   Mountains. The highest peak is Carrauntuohill, which is 1041 m
   (3414 ft) high. It is in the Macgillycuddy's Reeks, a range of
   glacier-carved sandstone mountains in County Kerry, in the south-west
   of the island. The mountains are not high - only three peaks are over
   1000 m (just) and another 455 exceed 500 m.

Rivers and lakes

   The main river in Ireland is the River Shannon, 386 km (240 miles), the
   longest river in either Ireland or 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 biggest. 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, and River Boyne. (See the list of
   rivers in Ireland.)

   Lough Neagh, in Ulster, is the biggest lake in Ireland. 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. (See the list of Irish loughs.)

Inlets

   Topography of Ireland
   Enlarge
   Topography of Ireland

   Beginning with County Donegal, Lough Swilly separates one side of the
   Malin 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, 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, County Donegal is the most northern 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, County Wexford is
   another extreme point of Ireland, being the southeasternmost point of
   Ireland.

   Further along the coast is Hook Head, also in County Wexford, while the
   Old Head of Kinsale in County Cork 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. Hags 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, County Mayo is the northwesternmost point of Connacht.

Islands and peninsulas

   Dingle Peninsula as viewed from Banna Strand
   Enlarge
   Dingle Peninsula as viewed from Banna Strand

   Achill Island, County Mayo in the northwest of Ireland 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 County Galway, host to an Irish-speaking
   community, or Gaeltacht. Valentia Island off the Iveragh peninsula in
   County Kerry is also one of Ireland's larger islands, and is relatively
   settled, as well as being connected by bridge at its southeastern end.
   Omey Island, off the coast of Connemara in County Galway 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 in County Down 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, although 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. Its most southerly 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 south-west to the north-east, 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 for the period 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.
   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 Republic of Ireland. The map shows
   the county boundaries for all 32 counties.

Map of Ireland with numbered counties        Republic of Ireland
                                       1. Dublin
                                       2. Wicklow
                                       3. Wexford
                                       4. Carlow
                                       5. Kildare
                                       6. Meath
                                       7. Louth
                                       8. Monaghan
                                       9. Cavan
                                      10. Longford
                                      11. Westmeath
                                      12. Offaly
                                      13. Laois
                                      14. Kilkenny
                                      15. Waterford
                                      16. Cork

                                                         17. Kerry
                                                         18. Limerick
                                                         19. Tipperary
                                                         20. Clare
                                                         21. Galway
                                                         22. Mayo
                                                         23. Roscommon
                                                         24. Sligo
                                                         25. Leitrim
                                                         26. Donegal

                                                                                    Northern Ireland
                                                          1. Fermanagh
                                                          2. Tyrone
                                                          3. Derry/Londonderry
                                                          4. Antrim
                                                          5. Down
                                                          6. 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 parts, North Tipperary and South Tipperary. 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 the Republic of Ireland, 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.

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