Ice Ages
Caught in the ebb and flow of the last Ice Ages over the last 2 million years, Ireland was at various times largely glaciated and completely land-locked as a part of the continent of Europe. Ireland was an island about 125,000 years ago when the sea level appears to have been very close to its present position. The sea level dropped 130 m (426 feet) or more during the interval from around 30,000 to 15,000 years ago, when Ireland became part of continental Europe [again], and sea levels have been generally rising ever since, albeit at a much slower rate.
In and around 20,000 years ago the area that would later reform the British Isles was mainly covered by a thick sheet of ice. This was during the last maximum expansion of the polar ice caps when sea levels were about 120 meters lower than today.
Ice Age Europe After a period of about 18000 BC - 16000 BC the thick glacial ice could expand no more and slowly began to melt or evaporate. At the same time the sea levels slowly began to increase. The figure to the left represents Europe in a period just after the ice sheet recedes from southern Ireland. Take special notice of the land mass connecting northern France with Ireland.
By about 12000 BC plant cover began to appear in Ireland. For a thousand years, Ireland was a place of open meadows. Possibly still not an island, Ireland begins to take shape about 12,000 to 11,000 14C years ago (perhaps 11500 to 10000 BC). About 11000 BC junipers began to appear. This, tough, low-statured evergreen survives well on poor soils, and thrived in the warming climate. Other plants and animals, including the Giant Deer and Reindeer, also arrived, crossing land bridges from the English mainland ito Ireland. At 11,000 to 10,000 14C years ago (or perhaps 10500 to 9000 BC) the ice fields are shown to have receded a great deal.
Estimated between 11000 to 9000 BC the earth's temperature fluctuated, dropped overall, and subsequent periods of glaciation again occurred in Ireland. Possibly due to disease and/or a loss of food supply, the Giant Deer (Megaceros) became extinct in Ireland and the Reindeer disappeared from Ireland.
Ireland 13000 BC Dates on the freshwater sediments found on the shelf of the Irish Sea, coupled with the results of geophysical modelling of Earth crustal rebound from ice loading, suggest a severence of any landbridge connection between Britain and Ireland by 10000 BC (again, plus or minus a few thousand years depending on the paleogeographic model). It is interesting to note that some ice formations had receded into Ulster and northern Scotland.
After about 9000 BC, the climate again warmed, the juniper spread, and the birch appeared in large numbers for the first time. Pine, elm and other forest trees also appeared, and Ireland began a long-term process of forestation. Other plants and animals crossed the land bridges as well. Red deer, wild boar, possibly bears, red squirrels, pine-martens, Wolves, foxes, stoats, and eagles and other birds of prey took up residence. Fish and game birds were soon present in abundance.
The first definite evidence of human settlement in Ireland dates from 8000 to 7000 BC. They are known from early archaeological findings to have made an appearance in the far north in the lower Bann valley near present-day Coleraine and in the southwest in the Shannon estuary. Later they are thought to spread northeast along the coast of Antrim and followed the Bann upstream to Lough Neagh. They also settled down to an industrious existence on the shore of Larne Lough just north of present-day Belfast, where they chipped flints for implements. These people, mesolithic hunter-gatherers without domestic animals or farming skills, huddled for the most part along the coasts and waterways. As a consequence, these early arrivals hadlittle impact on the environment.
One of the earliest claimed radiocarbon dates for the human inhabitation of Ireland was about 7490 bc. The sample that documents this date was obtained from a primitive settlement that contained charcoal remains at Woodpark in County Sligo.
The oldest peats within the vast areas of Ireland's peatlands were formed in the midlands about 9000 years ago (c 7000 BC). Over time the following trees make their appearance into the peat deposits archaeological record:
1.birch
2.willow
3.pine
4.hazel
5.elm
6.oak
7.alder
8.lime.
One of the oldest and best documented sites of early human habitation on Ireland is Mount Sandel, County Derry, investigated by Peter Woodman in the 1970s. The excavations uncovered hearths and postholes from early Mesolithic dwellings.
Radiocarbon dates show the site was occupied about 7000 - 6500 bc. Early Mesolithic people mainly used small flint blades called microliths, many of which have been found in the area around the site. In the absence of large animals at this period in Ireland these Mesolithic people appear to have relied upon a diet of wild boar, birds, fish and hazelnuts.
Another documented site of a similar age to Mount Sandel is Lough Boora, near Kilcormac in County Offaly. Although dwellings were not found, an assemblage of flints and polished stone axe-heads were also recorded for this Mesolithic site. Further documenting the more widespread appearance of Mesolithic people in Ireland (than was first thought) include the flintwork found in the valley of the Blackwater in Munster.
A wide range of dates have been offered for Ireland to become a separate island, i.e. for the closure of landbridges between Britain and Ireland. Estimates have generally ranged anytime from about 10000 BC to 5700 BC. Once Ireland became an island the days of easy migration were over, and subsequently, any animals that couldn't fly or swim could only make the journey by means of human intervention. Long after the connection between England and Ireland was severed, England was still a peninsula of Europe, and so the migration of plants and animals moving northward into the lands abandoned by the ice continued to enter England for some time after the flow to Ireland had been cut off. As a result, England developed a much greater variety of plants and animals than Ireland. There are approximately 30% less species in Ireland's natural environmental record (e.g. plants) in comparison to Britain.
