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| 14 Mar 2008 06:08:27 pm |
 "Landscapes of Ice Age Ireland" by Prof. Chris D. Clark |
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Above: Slide showing the retreat of the Irish Ice Sheet
Above: Slide showing showing undersea landscape from which extent of glacier ice sheet can be postulated, data collected from fishing trawlers
I had an extraordinarily interesting and pertinent evening yesterday.
I am in talks with the Leitrim Environmental Education Officer, Aine Carr, with regard to developing an outreach education project for young people living in Glenade and Glencar. This would be developed out of my research into the glaciation events which carved out these landscapes. Subsequent to being in touch with Aine, she informed me she had just heard on the Pat Kenny radio show that Professor Chris Clark was giving a talk in Enniskillen that evening with regard to his research into the history of glaciation in Ireland - auspicuous events! This was with particular regard to how this has sculpted the landscape we have inherited today, but also how our reading of this landscape can help us understand contemporary glaciated landscapes and their retreat due to climate change. Facinating stuff.
Professor Clark is a paleoglaciologist with the University of Sheffield who has spent 20 years studying the extent and dynamics of former ice sheets . His primary investigative method is the use of Earth Observation (EO, ie satellite imagery) to gain a larger scale perspective than is permitted by field observations alone. Interestingly I feel the perception of landscape I wish to develop is a corollary but of course very different to Professor Clark's satellite views. As he says about examing satellite imagery: 'I know the landscapes very well, but not the places'. Professor Clark reckons he 'knows every square KM of Glaciated landscape in the world through satellite, but I don't know the places'
I am very of interested at coming at this from the other direction, from the valley floor of Glenade/Glencar...but to go all the way towards making a full linkage with his satellite imagery. To garner specific computer models of glaciation in Glencar and Glenade would be facinating.
An interesting point: He reckons when the Irish ice sheet melted it added 30cm to global sea levels...if Greenland ice cover melts we can expect 7M!
Another interesting point: Ireland was one of the first places to have being recognised and studied as a glaciated formed landscape in the 1860s. We gave the science of glacial morphology the terms DRUMLIN and ESKER (derived from eiscéar, to cover). Abu! To put this within a historical context, during this era Darwin was in the Galapagos Islands formulating his idea of 'evolution'.
I am hoping to contact Professor Clark soon with regard to New Sites, New Fields and our agenda.
http://www.shef.ac.uk/geography/staff/clark_chris/index.html |
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Category : geology
| Posted By : Gareth |  Comments[59] |  Trackbacks [0] |
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| 10 Feb 2008 02:05:38 pm |
| Ice Sculpture - ice as medium, not material... |
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This idea of looking at the valleys' of Glencar and Glenade as the indexical traces of glaciers has really facillitated a shift in my perspective in experiencing these landscapes. I am really interested in how to further articulate, communicate and share this perspective, especially with regard to climate change etc.
I am considering some sort of interstitial intervention which at once would connect with the (pre)history of this site, but also with current and future projections for landscape change both within an Irish bioclime and a macro climatic context. |
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Category : geology
| Posted By : Gareth | Comments[42] | Trackbacks [0] |
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| 05 Dec 2007 02:14:36 pm |
| Landmark events 17,000 years ago... |
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Imagine a mountain of ice, grinding by, dredging thousands of feet of dirt and rock, and dropping house sized boulders in its wake.
- Gretel Ehrlich, From The Future of Ice
This is the view down the Glenade Valley towards the coast (home to the Dobharchu). I am really interested in this U shape as an indexical mark of sorts, that almost represents a vacant cast or something of the glacier which scored and carved its way through the landscape leaving us with the landscape we have today. Similar to the work of Rachel Whiteread, I am interested in how this negative space, (which we now inhabit) might serve as a repository of memory, a territory for interpreting events, or even a backdrop for commemoration, reflection and consideration of current glacial movements, further north or in the Alps perhaps.
In her book 'The Future of Ice' which is a meditation of sorts on our environmental plight with various remote and cold places around the world serving as backdrops, Ehrlich discusses glaciers and ice as markers of time and impermanence. I think the notion of ice as a time based entity contingent on its surrounding climatic and enviromental context is a really interesting idea. Our sense of sustained environmental transition (whether it is geological change over millenia or subtle climatic change over decades) is so myopic, it is really profound. I am interested in mechanisms to note and reflect upon this myopia, and perhaps be humble in acknowledging it.
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Category : geology
| Posted By : Gareth | Comments[42] | Trackbacks [0] |
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| 23 Oct 2007 01:20:24 pm |
| NSNF - The Island of Ireland - Land use |
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NSNF - The Island of Ireland
Irish Landbridge.
Ireland was at various times largely glaciated and completely land-locked as a part of the continent of Europe. Believed to have been 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. 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 radiocarbon 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 into Ireland. 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.
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 severance 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 15000 years ago the landbridge was thought to be in the south, at a time when the glacial ice 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 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: birch, willow, pine, hazel, elm, oak, alder, and lime.
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.
It is possible, even likely, that there was migrant human habitation previous to the Mesolithic era, although no conclusive remains have survived, distinctive of succeeding settlements. It is important to note, that no extensive excavation efforts have been staged as yet (c. 1994) to explore the sites which could possibly date to earlier periods.
Throughout Ireland, the Later Mesolithic appears to consist of short-term encampments associated with aquatic ecosystems. Ireland's oldest known boat, a canoe, is dated to about 5000 BC during the later Mesolithic period.
Human Settlement of Ireland
Mesolithic
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 had little 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. One of the oldest and best documented sites of early human habitation on Ireland is Mount Sandel, County Derry. 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.
Neolithic
The Neolithic, or New Stone Age, period has been cited from about 4000 to 2500 BC. The general pattern of carbon-14 dating determinations suggests that the Neolithic Period in Ireland began about 3000 bc (un-calibrated radiocarbon years). Neolithic migrant men and women were Ireland's first farmers who raised animals and cultivated the soil.
A major production and use of Irish Stone Axes is noted during Neolithic times. Stone axes are however known to have been in use from the earliest known phase of human settlement in the Early Mesolithic Period (c. 7000 BC). Over 20,000 axes have been found. The earliest Neolithic pottery found in Ulster (Lyles Hill pottery) is similar to pottery found in northern Britain, suggesting that some of the earliest Neolithic colonists may have come to Ireland from northern Britain.
Around 3800 BC Neolithic agriculturists began arriving in large numbers. These early farmers were the builders of the famous mounds and passage tombs, which are more densely packed into Ireland than into any other country. Domesticated cattle, sheep and goats were imported to Ireland at the beginning of the Neolithic period, together with cereals.
Neolithic farmers may have lived in larger communities rather than simply in isolated farmsteads. This is illustrated by the Céide Fields site in Co. Mayo, where an extensive Neolithic field system with stone walls has been preserved below a thick layer of peat.
The oldest known Neolithic house in Ireland (or Britain) was a wooden house, 6.5m by 6m, uncovered at an excavation at Ballynagilly, near Cookstown, County Tyrone. It was radio-carbon dated to approximately 3215 bc. This is only slightly later than the first record of (domesticated) cattle, datable to about 3430 bc, in County Down.
Megalithic structures
Court cairns and Passage cairns (passage tombs?) may be found dating from the Neolithic, perhaps beginning as early as 4200 to 3500 BC. The Passage Cairn (grave?) of Carrowmere (near the mouth of the Boyne river) has been dated (by some) from about 4200 BC. The Passage cairn at Newgrange has been dated to about 3200-3100 BC. In all some 300 Passage cairns have been identified, with many found along a line from County Meath to County Sligo. This form of megalithic structure is distinguished as a round mound of earth and stone having, roughly in the center, a burial chamber which is reached by a passage leading in from the edge of the mound. Excavation of Passage cairns have produced cremation (burnt human remains) burials, with inhumation (interment of human bodies) being generally rarer. It is probable the Passage Cairns were Sacred Temples of Religious and Ceremonial importance, much as present day Cathedrals are primarily places of worship where Church and Royal dignitaries may be laid to rest. The astronomical alignment of some of these cairns, notably at Newgrange and Loughcrew, seem to place credence to the view they were used for ceremonial, and possibly astrological, purposes.
Court cairns (like the one at Creevykeel, Co. Sligo) are almost exclusively found in the northern part of Ireland, with large concentrations in northern Connaught and across southern Ulster. Over 350 Court cairns have been recognized as of this writing. They are generally recognizable as a long mound (of stones), with a forecourt at one end leading into a long and often subdivided chamber. Considerable variations on this basic scheme are known. Cremation burials have been associated with Court cairns, but it is not clear whether their primary function was that of a place of burial. It is worth noting that Court cairns are never grouped together as cemeteries, and in their isolation, may have served as the focal cult center for a scattered population.
Portal tombs (or chambers) are claimed to be mainly constructed between 3000 and 2000 BC. The majority of these are found in the north of Ireland, with another concentration of tombs found along a line from Dublin toward Waterford. About 161 Portal tombs, including those more commonly called dolmens, have been found. They are generally classified as above ground burial chambers, consisting of a number of upright stones covered by one of two capstones, and sometimes placed in a long or round mound.
The Copper and Bronze Age
The Bronze Age in Ireland is normally considered to start in a range from 2500 BC to 2000 BC, and to end anywhere from 600 BC or 300 BC. The construction of the Passage tomb at Tara known as Duma na nGiall (the mound of the Hostages) has been carbon dated between 3030 to 2190 (14C) bc. Throughout the early Bronze Age Ireland had a flourishing metal industry, and bronze, copper, and gold objects were exported widely to Britain and the Continent. More Bronze Age gold hoards have been discovered in Ireland than anywhere else in Europe. The earliest metal tools found in Ireland were made of copper and were concentrated in Munster, where early copper mines have been noted. The prehistoric mines on the slopes of Mount Gabriel in Co. Cork consist of some 25 mineshafts. Some of the more prolific copper items that have been found from the early Bronze age include axes, daggers and halberds.
About 2150 bc the "Bell-Beaker" culture, named for the bell-shaped vessels they left behind, began to make an appearance in Ireland. The culture is known as one of more technologically advanced people, who made and used metal and finely polished stone tools. It has been suggested that with this culture may have come the original language which evolved into Irish Gaelic, a very difficut proposition to actually prove.
Wedge tombs (about 400) are considered to be built mainly between 2000 and 1500 BC, and Bell-Beaker pottery are often associated with them. Similar tombs also associated with Beaker finds are common in the French region of Brittany, and the origin of the Irish series seems connected to this region. Wedge tombs are found scattered throughout northern Ireland, with large concentrations in the west, particularly around County Clare, northern Connaught, and County Cork. For the most part Wedge tombs have long, rectangular burial chambers usually roofed with large stones, and placed in a long, wedge-shaped mound.
Other monuments to be mentioned around the Beaker-using period is that of Stone Circles. Of the more than 200 stone circles almost 100 are concentrated in the southwestern counties of Cork and Kerry, many of them consisting of no more than five stones. Somewhat unexpected in the southwest of Ireland are four stone groupings known as "Four Posters", which find their closest counterpart in northern England and Scotland. Another great concentration of stone circles is found in central and southwestern Ulster in the north of Ireland, often consisting of more stones than found in the southwest of Ireland.
The Late Bronze Age begins around 1200 BC, and brings to Ireland "a whole new range of bronze implements and weapons, such as socketed axe-heads and swords." This is an age strongly identified with the appearance of the first "hill forts" and "ring forts", a mark of Hallstatt Celtic culture, which appear only to date back to the seventh century BC in central Europe. A common type of dwelling in use at this time is said to be crannóg, an artificial island, palisaded on all sides, constructed in the middle of a lake.
The Ring Fort at Mooghaun South in County Clare shows evidence for settlement during the Late Bronze Age after its construction around 1260-930 BC (or earlier). Other evidence of ring forts seem to suggest a Late Bronze Age start for construction of this type, although a wide range of later dates have also been suggested.
Celtic Culture
Cultural change in the later prehistoric period in Ireland was traditionally explained in terms of the emigration of Celtic peoples from continental Europe. In contrast, modern archaeological research has produced a growing consensus that the period was marked by general cultural continuity with little evidence of external intrusion. The only historical reference to a Celtic invasion is in Britain, which is that of the Belgae who conquered parts of the south east of England in 75 BC.
By about 700 BC, swords of the Hallstatt type start to appear in Ireland, but these were made of bronze, not of iron, so it seems likely that these were bronze copies made by local smiths. Celtic languages and culture are thought to have their roots in the latter part of the Hallstatt culture (about 800 to 475 BC) during the Iron Age in the upper Rhine and Danube valleys of central Europe.
The arrival of the Iron Age may have begun as early as 500 BC and lasted up to 500 AD, although there have been no clear indications iron was the predominant metal for weapon making in Ireland until around the third century BC. Long earthworks such as the Dorsey in Co. Armagh and the Black Pig's Dyke, which run across much of lower Ulster, were thought to be built during the Iron Age. The earliest waves of Celtic migrants may have reached the country as early as the 6th century BC (or before) with subsequent groups arriving up to the time of Christ. The Celts belonged linguistically to the great Indo-European family. They soon came to dominate Ireland and it's earlier people, as told to us by the great Irish sagas of the pre-Christian period.
The La Tène culture (which may date in Ireland from 300 BC or earlier) is represented in a unique stlye of metalwork and some stone sculpture, mainly found in the northern half of the country. Connections with northern England are apparent. By about 100 BC Irish bogs were being drained for more farmland, and some of the forest had been cleared. This is often associated with the arrival of La Tene Celtic culture into Ireland.
Hill-fort building seems very characteristic of the Iron Age, they are more numerous in the southern half of Ireland which is an area almost entirely lacking in La Tene decorated material, suggesting a dual nature of Irish culture or population during the Iron Age.
Historical Records
The earliest possible written reference to Ireland is in the Peripolous of Himilco, the Carthaginian who wrote in the 6th century BC. In it he references Celtic tribes on the North Sea, as well as in France and Spain. Writing in the late 4th century BC Pytheus refers to the British Isles as the Pretanic islands, from Priteni, terms which allude to a Celtic connection for the islands. A Greek name for the island as Ierne, as mentioned by Strabo in his work Geography. In De Bello Gallico, written about 52 BC, Caesar refers to name Hibernia. Ptolemy produced the first map (of Hibernia) with identifiable features about the middle of the 2nd century AD. In his Ora Maritima (4th century AD), based on a Greek original of the early 6th century BC, Festus Rufus Avienus refers to Ireland as Insula sacra (holy island) and to the inhabitants as gens hiernorum. The modern country's name of Éire (Gaeilge for Ireland) is thought to be derived, among others, from an early tribal group of Ireland referred to as the Érainn (aka Iverni). |
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Category : geology
| Posted By : David | Comments[55] | Trackbacks [0] |
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