Hyenahall’s Cold Fauna – Emerald Archives

Dateline

“31,450 BCE” is a modern chronological label, not a date at which archaeology can identify a particular Irish event. At this depth of time, calendar-year precision is unavailable. Converted approximately into the archaeological convention of calibrated years before present (where “present” is 1950), it falls around 33,400 cal BP, within the Late Pleistocene and Marine Isotope Stage 3 (MIS 3). The most responsible account is therefore regional and range-based: it concerns the changing conditions of Ireland during an Ice Age interval, not a named community’s actions in one year.

Evidence closest to this notional horizon comes chiefly from two very different archives. At Derryvree, near Maguiresbridge in County Fermanagh, organic freshwater sediments lie between two layers of glacial till. Their position demonstrates a sequence: ice deposited the lower till; a period without overriding local ice allowed wetland sediments, plants and insects to accumulate; later ice covered the deposit with a second till. A radiocarbon determination from the organic series, BIRM-166, has been calibrated broadly to about 36,900–31,700 cal BP. That range includes the approximate date represented by 31,450 BCE, but it cannot make Derryvree a snapshot of that individual year.

An Ireland Between Advances

Derryvree is important because it contradicts any simple image of an Ireland permanently entombed beneath ice throughout the last glacial period. Its freshwater mosses, sedges and other plant remains, together with a cold-climate insect fauna, record a treeless periglacial wetland. The landscape was severe, but it supported standing or slow-moving freshwater, vegetation and invertebrate life. It was neither modern bog nor a leafy woodland: the evidence is for open country shaped by cold, short growing seasons, frost action and sparse cover. Similar sub-till deposits at Greenagho and Hollymount in Fermanagh show that the region preserves several fragments of non-glacial or interstadial environmental history, rather than a single unchanging ice regime.

There are necessary limits to the inference. Derryvree proves conditions in one part of Fermanagh during a dated interval, not that every part of Ireland was simultaneously free of ice, nor that the exact plants and insects survived continuously through its whole calibrated range. Sediments can also be reworked, and conventional radiocarbon results carry substantial uncertainty so far back in time. Nevertheless, the buried wetland establishes an essential point: before the fullest expansion of the last Irish Ice Sheet, parts of the island could contain ice-free or lightly glaciated habitats.

The wider trajectory was towards greater glaciation. Reconstructions of the British–Irish Ice Sheet place its major Last Glacial Maximum phase later, broadly around 26.5–19 thousand years ago, with extensive ice covering all or almost all Irish low ground. Research on southern Ireland indicates that the main build-up of the last Irish Ice Sheet followed earlier ice-free conditions around 34 ka and did not reach the south coast until after about 24 ka. Thus 31,450 BCE belongs not to the height of the last glaciation, but to a long, unstable approach to it: a time when local environments and routes across the landscape could alter profoundly over millennia.

Castlepook’s Animal Archive

The most vivid Irish evidence for this broad period lies far to the south, at Castlepook Cave near Doneraile in north County Cork. Also called Mammoth Cave, it is a limestone cave system whose galleries acquired evocative names during early excavations, including Hyenahall and Elephant Hall. More than 2,000 bones have been recovered, and direct dates on individual specimens span a very long interval, from roughly 45,700 to 19,950 years BP. Castlepook is therefore not a sealed occupation floor and should not be treated as one moment in time. It is a repository assembled through animal activity, deaths, scavenging, water movement and disturbance, then partly excavated by antiquarians long before modern recording standards.

Even so, its fauna gives Ireland around this era a remarkable ecological depth. The cave has produced remains of woolly mammoth, giant deer, reindeer, brown bear and spotted hyaena, alongside later Ice Age records of Arctic fox, wolf, Norwegian lemming and collared lemming. Not every species need have lived together, and not every dated bone belongs close to 31,450 BCE. Yet the assemblage securely establishes that southern Ireland was connected to the wider north-west European world of large grazers, browsers, predators and scavengers during MIS 3. It was an open, cold landscape in which herds and carnivores mattered far more than forests, fields or permanent villages.

Hyenahall’s name is more than picturesque. Spotted hyaena is known in Ireland from Castlepook, and a resident carnivore population helps to explain why bones accumulated in caves. Hyaenas could carry carcass parts underground, gnaw and break them, and leave remains that later water or excavation moved again. That taphonomic history matters when interpreting every apparent trace of people. A bone within a cave is not automatically the refuse of a human meal; it may be evidence of predation, scavenging, transport or natural death. The central archaeological task is to separate those processes rather than choose the most dramatic story.

The Reindeer Femur Question

One Castlepook object nevertheless makes this period unusually significant. A reindeer femur has been reported as approximately 33,000 years old and bears a deep linear mark which zooarchaeologist Ruth Carden has interpreted as damage made by a sharp stone implement while the bone was fresh: potentially a butchery mark. If that diagnosis and its chronological association are sustained, it would be evidence that a person processed a reindeer in Ireland during the Upper Palaeolithic, vastly earlier than the long-established post-glacial record of human activity. It is a serious and potentially transformative claim, not a licence to invent an Ice Age Irish population.

The distinction between the secure and the suggestive is crucial. Direct radiocarbon dating can date the animal bone, within an error range; microscopy and taphonomic analysis must determine whether an incision is humanly made rather than carnivore, sedimentary or excavation damage. A genuine cut mark would demonstrate an encounter with, and processing of, an animal. It would not establish a camp, a house, a hearth, a hunting territory, a burial ground, a population size or uninterrupted occupation. No securely associated stone-tool assemblage, dwelling surface or human remains of this age has been published from Castlepook. A 2022 research excavation, supported by the Royal Irish Academy, illustrates both the cave’s promise and the need for carefully controlled new evidence.

People Beyond the Irish Record

Across Europe, Homo sapiens groups of the Upper Palaeolithic had sophisticated ways of making stone, bone and antler equipment; they hunted and scavenged animals, made clothing and shelters, and maintained social links across large territories. Such comparisons show that a short human visit to Ice Age Ireland is plausible. They do not prove that a particular technology, language, ritual, artistic practice or kinship system existed here at this time. Ireland has no securely demonstrated art, ornament, grave, house or tool tradition dating to around 33,400 cal BP. A responsible history must preserve that silence.

Accordingly, political affairs, diplomacy and organised conflict cannot be recovered for Ireland in this period. There were no states, kingdoms, written treaties or named leaders, and there is no archaeological basis for projecting later Irish institutions backwards into the Pleistocene. Nor is there direct evidence for trade in the usual archaeological sense of exchanged objects or materials. If people reached the island, their movement would have depended on environmental knowledge and social connections extending beyond a single locality; that is a cautious inference from hunter-gatherer survival elsewhere, not an Irish fact demonstrated by Castlepook.

Geography remains an important uncertainty. Global sea levels were lower during glacial times, exposing areas of the present seabed, but the exact character, duration and passability of connections between Ireland and Britain changed with sea level, ice loading and local topography. Modelling indicates that Ireland was separated from Britain by about 16,000 cal BP, long after the period considered here; it does not permit a simple assertion that visitors at 31,450 BCE merely walked across a stable land bridge. Any route, whether over exposed ground, ice or water, must remain undetermined without more direct evidence.

A Landscape, Not a Nation

Everyday life is therefore best described first through ecology rather than imagined domestic scenes. Reindeer and mammoth needed extensive food landscapes; hyaenas, wolves and bears occupied different predatory or omnivorous niches; lemmings and Arctic fox point to cold-adapted conditions. Wetlands such as Derryvree offered fresh water and summer plant growth, while limestone caves such as Castlepook became traps, dens and archives. Seasonal animal movement may have linked such places, although Ireland’s fossil evidence is too sparse to reconstruct a precise migration calendar.

For this date, the principal development in Irish history was environmental. Ice, cold, vegetation and animal movement governed what could live on the island and whether people could enter it. The Derryvree beds show an ice-free freshwater world within a glacial sequence; Castlepook’s bones show a rich cold-stage fauna; the marked reindeer femur offers a possible, still incomplete, glimpse of human action. Later expansion of the Irish Ice Sheet would erase, bury or disturb much of the earlier surface record. What survives is fragmentary, but it is enough to replace an empty white map with a dynamic Pleistocene Ireland—wet in places, open, dangerous, inhabited by large animals, and poised before a deeper freeze.

Primary Sources

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