North And West By The Caledonian Mountains example essay topic

Geo essayIrelandIreland is an island on the western fringe of Europe between latitude 51 1/2 and 55 1/2 degrees north, and longitude 5 1/2 to 10 1/2 degrees west. Its greatest length, from Malin Head in the north to Mize n Head in the south, is 486 km and its greatest width from east to west is approximately 275 km. Since 1921 the island has been divided politically into two parts. The independent twenty-six county area, comprising 70,282 sq. km, has a population of 3,523,401 (1991). Northern Ireland, which is part of the United Kingdom and contains six of the nine counties of the ancient province of Ulster, has a population of 1,569,971 (1991). In 1973 Ireland became a member of the European Union (EU).

The two great mountain systems of Europe, north of the Alps, converge westwards to meet and mingle in Ireland. The older (Caledonian) extends from Scandinavia through Scotland to the north and west of Ireland, where it gives rise to the rugged and mountainous landscapes of Counties Donegal, Mayo and Galway. The higher mountains are of quartzite that weathers into bare, cone-shaped peaks such as Errigal (752 m) in Donegal, Cro agh Patrick (765 m) in Mayo and the Twelve Bens in Galway. Structures of similar age are responsible for the Wicklow and Black stairs Mountains that extend southwestwards from Dublin Bay for a distance of more than 100 km.

In these, long-continued denudation of a great anticlinal structure has exposed a granite core that now forms rounded peat-covered uplands, the crests being notched in places by glacial cirques. Deep glacially modified valleys of which the best known is Glenda lough in County Wicklow penetrate the mountains. The younger structures (Armorican) extend from central Europe through Brittany to southern Ireland, where they reappear as a series of east-west anticlinal sandstone ridges separated by limestone or shale-floored valleys. The hills rise in height westwards culminating in Carrantouhill (1041 m) in the Magillycuddy Reeks, the highest mountain in the country.

The famous Upper Lake of Killarney nestles in the eastern slopes of this range. The sea, giving rise to a number of long deep inlets has flooded the valleys separating the western extension of these mountains. In northeastern Ireland basaltic lavas spread widely over the existing rocks in Eocene times and now form the bleak plateau of east Antrim. Westwards the basalt is down warped and the resultant drift-covered lowland is occupied in part by Lough Neigh, the largest lake in Ireland. The heart of the country is limestone- floored lowland bounded on the south by the Armorican ridges and on the north and west by the Caledonian Mountains. This lowland is open to the Irish Sea for a distance of 90 km between the Wicklow Mountains and the Carling ford peninsula, giving easy access to the country from the east.

It also extends westwards to reach the Atlantic Ocean along the Shannon Estuary, in Galway Bay, in Clew Bay and again in Donegal Bay. Numerous hills break the monotony of the lowland that rises westward towards the coast in County Clare where it terminates in the cliffs of Mother, one of the finest lines of cliff scenery in Western Europe. Much of Ireland was covered by ice during the Pleistocene period. This ice finally melted away about twelve thousand years ago, leaving behind evidence of its former presence in most of the minor physical features of the landscape. Throughout the greater part of the lowland the bedrock is hidden by glacial deposits, which, in the north central part of the country, form a broad belt of small hills (drumlins). The glacial cover also modified the early drainage pattern and in places created groundwater conditions which facilitated the growth of peat bogs.

Numerous slow- flowing streams, the largest of which is the River Shannon, 340 km in length, drain the lowland. In its middle course this river broadens into a number of attractive lakes but as it approaches the sea its gradient steepens. This is the location of Ireland's earliest hydro-electric power scheme. The main rivers draining eastwards are the Lagan, which flows into Belfast Lough, the Liffey, with Dublin at its mouth, and the S laney, which enters the sea at Wexford. In the south of Ireland the long east-west synclinal valleys are occupied by such rivers as the Sir, the Lee and the Blackwater which reach the coast by making right-angled turns to pass southwards through the sandstone ridges in narrow gorge-like valleys. Ireland's mild and equable climate is a reflection of the fact that the relatively warm ocean waters of the North Atlantic Drift bath its shores.

Valencia, in the extreme southwest, has an average January temperature of 7! C and a July temperature of 1 5! C, a range of only eight degrees. The figures for Dublin are 4.5! C in January and 1 5.5! C in July, a range of eleven degrees.

Extremely high or low temperatures are virtually unknown. Rainfall is heaviest on the westward facing slopes of the hills where it may exceed 3,000 mm in Kerry, Mayo and Donegal. The east is much drier and Dublin records on average only 785 mm annually. The outstanding feature of the Irish weather is its ability to change, a characteristic, which it shares with all the countries that lie in the path of the temperate depressions.

However more stable atmospheric conditions may arise in winter with the extension of the continental high-pressure system bringing clear skies and cool conditions, especially to the eastern part of the country. In summer an extension of the Azores high-pressure system may bring periods of light easterly winds and bright sunny weather. Most of the soils of Ireland are derived from glacial drift and reflect its varied composition and texture. There are large areas of fertile gray-brown podzolic soils on the better-drained parts of the lowland.

These give way to less fertile acid brown earth where the parent material is low in lime or to gelled soils where the drainage is poor. Thin acid peat soils are widespread on the hills. (1,007 words Mr. G. ).