Maguirebridge’s Buried Wetland

Dateline

31,799 BCE is a modern chronological label, not a year that anybody in prehistoric Ireland could have named, recorded or commemorated. It falls roughly 33,750 calendar years before AD 1950, the conventional reference point for “before present” dating. No Irish archaeological layer can be assigned securely to that single year. Radiocarbon determinations measure residual carbon rather than a calendar date, and calibration at this depth of time produces ranges that may extend across centuries or millennia. The responsible subject, therefore, is Ireland during the broad interval around this nominal date: later Marine Isotope Stage 3, within the last Ice Age.

This was not yet the Last Glacial Maximum, when the British–Irish Ice Sheet would expand dramatically across Ireland and its surrounding shelf. Nor was it a familiar island of green fields, forests and settled communities. The evidence instead reveals a shifting, cold landscape in which areas of open ground, wetlands and perhaps local ice existed within a climate capable of changing sharply over long human lifetimes. Much has been erased or disturbed by later ice, rising seas and millennia of erosion. What survives is fragmentary: buried silts, pollen, plant remains, cave bones, landforms and laboratory dates.

Dating an Ice-Age Landscape

The date convention itself needs care. “31,799 BCE” is calculated backwards from the modern calendar and gives an appearance of precision that the evidence cannot match. Archaeologists and Quaternary scientists normally use radiocarbon years BP and calibrated calendar years BP. The internationally used IntCal20 calibration curve reaches back to 55,000 calendar years BP, but it does not turn a sample into a record of a particular season or year. A radiocarbon measurement dates the death of an organism, while the deposition, disturbance and excavation of its remains may all be later.

For this horizon, the most useful Irish chronological evidence comes from sequences that bracket environmental intervals rather than from a dated settlement. The key conclusion is secure in broad outline: parts of Ireland were ice-free during later MIS 3, before the main advance of the last ice sheet. The exact limits of ice, water and habitable ground changed over time and varied from region to region. It would be misleading to picture all Ireland as either an unbroken glacier or a wholly open plain.

Silts Beneath the Drumlin

The clearest local window lies at Derryvree, near Maguiresbridge in County Fermanagh. Roadworks in 1969 cut through a drumlin and exposed freshwater silts and fine sands sealed between two layers of glacial till. The sequence matters greatly. An earlier ice advance had deposited the lower till; a non-glacial freshwater environment then developed; later ice overrode and buried that archive beneath fresh till. The deposits are evidence for a major environmental reversal, not a chronicle of continuous annual accumulation.

Organic material from the Derryvree sediments produced a radiocarbon determination of 30,500 years BP, with a substantial uncertainty. Later calibration places the relevant range broadly at c. 36,900–31,700 calibrated years BP. The nominal date of 31,799 BCE falls within that range, but cannot be located at a precise point in it. Derryvree nevertheless demonstrates that north-central Ireland could support freshwater conditions during this part of the Late Pleistocene, before a later glacial expansion remodelled the ground.

The plant and animal traces from the buried sediments indicate open tundra and periglacial conditions. Grasses, sedges, herbs, mosses and low shrubs were better suited to the landscape than dense woodland. Wet ground lay beside shallow freshwater, while seasonally frozen soil and severe winters shaped drainage and vegetation. Occasional tree pollen should not automatically be read as evidence of local forest: pollen can travel far, and sparse woodland was not the defining character of this environment. This was a biologically active but exposed country, not an empty white wilderness.

Animals in Open Country

Cave assemblages from southern Ireland complement the Fermanagh environmental record. Castlepook Cave, also called Mammoth Cave, near Doneraile in north County Cork, has yielded remains attributed to woolly mammoth, reindeer, giant deer, brown bear, wolf, Arctic fox, mountain hare, lemmings and spotted hyaena. Shandon Cave near Dungarvan in County Waterford has also produced mammoth, reindeer, horse, bear, wolf and hare. Together, such remains show that Ireland intermittently supported a varied cold-stage fauna between at least about 45,000 and 20,000 years ago.

These lists must not be treated as a census of animals alive together in 31,799 BCE. Cave deposits can form over very long periods. Carnivores may carry bones into dens; animals can die in crevices; roof falls, water, sediment movement and early excavations can mix material from different episodes. Some of Castlepook’s oldest collections were recovered in the early twentieth century, before modern methods of fine-grained stratigraphic recording. Recent redating has shown that several earlier radiocarbon results underestimated the antiquity of southern Irish cave fauna, but it has also reinforced the need for caution when reconstructing individual events.

Even so, the fauna gives a credible impression of the food webs available in an open, cold landscape. Reindeer and giant deer browsed or grazed; mammoths required extensive forage; hares and lemmings occupied smaller ecological niches; wolves and hyaenas were predators and scavengers. Their presence suggests seasonal productivity in grassland, herb-rich tundra and wetland margins. It does not establish that every species shared one place at one time, nor that animal abundance made the country easy or safe for people.

The Castlepook Question

A reindeer femur from Castlepook has made this period especially important in Irish archaeology. Re-examination identified a deep linear mark interpreted as consistent with cutting or chopping by a sharp stone tool, perhaps during carcass processing. The bone has been reported as dating to about 33,000 years ago. If the modification was indeed made by people close to the animal’s death, it would indicate a human visit to Ireland far earlier than the long-recognised terminal-Pleistocene evidence from County Clare.

That is an important possibility, not a licence to invent an established Ice-Age population. The specimen came from an old cave collection rather than a modern excavation of an intact camp surface. No securely associated hearth, stone-tool assemblage, shelter floor, burial or repeated occupation horizon of comparable age has yet been recovered at Castlepook. The radiocarbon date dates the animal, not necessarily the making of the mark, its place of killing or the length of any human presence. Ongoing investigation at the cave has located undisturbed fossil-bearing deposits, which may eventually clarify the wider context.

The most defensible interpretation around this date is therefore modest. Small Upper Palaeolithic hunting parties may have reached parts of Ireland during a favourable interval of MIS 3 and may have exploited animal carcasses. They might have arrived across a changing north-west European landscape in which lower sea levels altered coastlines and routes. But there is no direct evidence for a permanent Irish population, a village, a named group or continuous occupation. Whether access was by exposed land, ice, short sea crossings or a combination of routes remains unresolved for this specific phase.

No Kingdoms, No Recorded Wars

Political affairs, diplomacy and formal institutions cannot responsibly be reconstructed for Ireland at this time. There were no written records, no known monuments, no proven settlements and no evidence for territorial states. Nor can conflict be inferred from the mere presence of predators or from damaged bone: gnawing, breakage and carcass scavenging belong first to natural and animal processes. If people were present, their social organisation would have been on the scale of highly mobile hunter-gatherer groups, but that is an inference drawn from wider Upper Palaeolithic contexts, not something demonstrated by an Irish camp.

The same restraint applies to religion, culture, learning, trade and everyday life. There is no Irish evidence from this horizon for ritual structures, art, burial practice, exchange networks, farming, pottery, metalworking or long-term houses. A possible butchered reindeer bone speaks most directly to practical knowledge: the use of a sharp implement on animal tissue and bone. It does not reveal a language, belief system or political identity. The absence of such evidence is not proof that people had no culture; it is a limit on what the Irish record can presently show.

Before the Major Advance

The greatest development relevant to this nominal year was environmental rather than political. Ireland stood within an unstable prelude to the most extensive phase of the last glaciation. During the following millennia, the British–Irish Ice Sheet grew and eventually covered Ireland and much of the continental shelf, reaching maximum extent broadly around 27,000–23,000 calibrated years BP. That later expansion would scour, bury and transform many older landscapes, leaving rare protected pockets such as Derryvree and cave deposits as vital witnesses.

Thus Ireland around 31,799 BCE is best understood through its buried wetland and cave-bone archives: a cold, open, changing land with freshwater refuges and substantial mammals, before the full glacial maximum. The possible Castlepook human trace makes the period unusually significant, but its ambiguity is part of the history. It reminds us that the earliest Irish past is not a sequence of confidently dated events, but a careful reconstruction from evidence that is precious precisely because so little of it survives.

Primary Sources

Tags: British-Irish Ice Sheet, Castlepook Cave, County Cork, Ireland Year by Year, Late Pleistocene, Marine Isotope Stage 3