Wogan Cave, beneath Pembroke Castle. Still being studied -- what will it tell us about the Devensian changes in local climate?
Climatic oscillations over the past 150,000 years. Based on the Sidestone Press diagram.
In Britain it is quite challenging to match up the archaeological / anthropological records with the Marine Isotope Stages given the numbering MIS3- MIS5. There are some mis-matches and some awkward fits. Probably as we should expect. It is widely believed now that during the Ipswichian Interglacial there was virtually no humanoid presence in the British Isles -- maybe because at the beginning of the interglacial sea-level rise was so fast that the North Sea and English Channel were flooded catastrophically before westward migrations could take place.
Fifty years ago it was widely assumed that the Ipswichian Interglacial ended about 70,000 years ago. Nowadays that termination date has been pushed back to 116,000 years ago, and there is an acceptance of a full interglacial (MIS5e) followed by a long "intermediate phase (116,000 - 71,000 yrs BP) of oscillating climate, with several substages including the Chelford Interstadial around 100,000 yrs BP.
In the following paper by Robert Dinnis most of the emphasis is on human occupation of the British Isles in MIS3, with discussion of the importance of 6 Welsh bone caves, 4 in Pembrokeshire and 2 in the Gower. In the fascinating Wogan cave, beneath Pembroke Castle, there is some evidence of Ipswichian bone remains, but the main sedimentary sequence speaks of intermittent, low density occupation by humans in MIS3. There do not appear to be any signs of a full glacial episode in the Early Devensian (MIS4) or mid Devensian (MIS3) which might back up the theory of an ice cover extending as far as Lundy Island at this time (see below).
However, there is still the possibility that the Wogan, like other bone caves in West Wales, was sealed by overriding ice during the LGM. Robert Dinnis and his colleagues have not as yet expressed a view on this.
The Early Upper Palaeolithic in British caves: problems and potentialRobert Dinnis
Jnl of the Royal Anthropological Institute
First published: 20 August 2025, pp 1-17
https://doi.org/10.1111/1467-9655.14313Abstract
Recent years have seen landmark progress in our understanding of early Homo sapienso ccupation of Europe, owing to new excavations and the application of new analytical methods. Research on British sites, however, continues to lag. This is because of limitations inherent in existing cave collections, and limited options for new fieldwork at known sites. Some of these limitations are described here. In the light of this, recent work at the new Early Upper Palaeolithic site of Wogan Cavern (Pembrokeshire) is outlined. Initial observations indicate a significant quantity of intact sediments and high-quality archaeological deposits amenable to modern research methods.
See also:
https://www.wogancavern.org/uploads/1/3/3/0/133004851/dinnis_et_al_2023_cks_wc22.pdf
In Britain, the boundary dates for Marine Isotope Stages (MIS) 3, 4, and 5 align with the standard European Quaternary chronology, though local stages like the Devensian and Ipswichian are used to describe these periods:
MIS 3 (c. 57,000 – 29,000 years ago): A complex, relatively mild (interstadial) period within the Last Glacial. In Britain, this includes the Upton Warren Interstadial (c. 44,000 – 42,000 years ago), a brief warmer phase marked by evidence of Neanderthal reoccupation.
MIS 4 (c. 71,000 – 57,000 years ago): A major cold, glacial and periglacial phase. During this stage, Britain saw significant ice expansion, with evidence suggesting the British and Scandinavian ice sheets may have merged in the North Sea. Further south, permafrost prevailed.
MIS 5 (c. 130,000 – 71,000 years ago): This long stage (almost 60K years) includes the last full interglacial and subsequent cooling phases:
MIS 5e (c. 130,000 – 116,000 years ago): Known as the Ipswichian Interglacial in Britain, the last time the climate was as warm as or warmer than today.
MIS 5d–5a (c. 116,000 – 71,000 years ago): Transitional phases leading into the main glacial. Notable British substages include the Chelford Interstadial (MIS 5c, c. 100,000 years ago) and the Brimpton Interstadial (MIS 5a, c. 80,000 years ago).
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So how do we move forward in our understanding of the various phases of the Devensian? One exciting line of research involves the dating of speleothems (mineral precitates including stalagmites and stalactites, associated with constantly running or dripping water). Most caves linked with running water hold speleothems; over time the process of precipitation and growth can be switched on and switched off as a result of climate change. The assumption is that during episodes of continuous permafrost -- for example at the peaks of a glacial episodes -- all water is frozen and immobilised. Speleothem layers oir periods of rapid accumulation can be dated with considerable accuracy using the Uranium / Thorium (U/Th) method.
The evidence from Welsh caves generally supports ice-free conditions in the early Devensian, though this period was likely a cold, non-glacial tundra environment rather than a warm one. While the Late Devensian glaciation (approx. 26,000–19,000 years ago) is well-documented as having obliterated much surface evidence, speleothem and sediment records within caves provide a more continuous timeline for the preceding stages.
Key Speleothem Evidence for Ice-Free Early Devensian in Wales:
• Continuous but Low Growth: Uranium-series dating of speleothems in the British Isles shows a period of "low but finite" growth between 90 ka and 45 ka (MIS 4 and MIS 3). This suggests that while it was too cold for the lush growth seen in interglacials, liquid water was still moving through the systems, which would be impossible under a permanent ice sheet or continuous permafrost.
• Cave Sequences as Refugia: In South Wales, coastal cave sequences such as Long Hole and Bacon Hole in the Gower contain Early and Middle Devensian deposits that are not found elsewhere because they were protected from later glacial erosion.
• Interstadial Peaks: Specific peaks in growth at approximately 76 ka, 57 ka, and 50 ka have been identified as indicators of Devensian interstadials (brief warmer pulses). These peaks confirm that ice had not yet advanced to cover these cave-bearing regions during the early part of the last cold stage.
• Ice-Free Uplands: While some geologists previously hypothesised an early Devensian ice cap in the Welsh mountains, the presence of speleothems and lack of unequivocal early glacial deposits suggest that these areas remained largely ice-free until the Late Devensian.
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The paper by Rolfe et al 2012:
The cosmogenic dating results presented by Rolfe et al in 2012:
"Paired 26Al and 10Be exposure ages from Lundy: new evidence for the extent and timing of Devensian glaciation in the southern British Isles"
C.J. Rolfe, P.D. Hughes, C.R. Fenton, C. Schnabel, S. Xu, A.G. Brown
Quaternary Science Reviews 43 (2012) 61e73
https://www.researchgate.net/profile/Christopher_Rolfe/publications
This paper has been hotly disputed by John Hiemstra, Simon Carr and others:
Landscape evolution of Lundy Island: challenging the proposed MIS 3 glaciation of SW Britain
Simon J. Carr, John F. Hiemstra, Geraint Owen, Proceedings of the Geologists’ Association 128 (2017) 722–741
Lundy Island, in the Bristol Channel of south-west Britain, holds a pivotal place in understanding theextent and timing of Quaternary glaciations in southern Britain, in particular the timing, extent anddynamics of the Irish Sea Ice Stream during the Devensian glaciation. New geomorphological observations and revised interpretations of geomorphological and cosmogenic exposure data lead to the conclusion that Lundy was not covered by ice in the last (Devensian) glaciation. Geomorphological features are related to surface lowering by means of granite weathering under mainly periglacial and cool-temperate conditions. Previously reported cosmogenic ages are re-interpreted to reflect a dynamic equilibrium of cosmogenic nuclide production and surface lowering during a prolonged period of subaerial granite weathering. This re-evaluation of the geomorphology of Lundy Island challenges recently proposed interpretations of early glacial cover of Lundy (MIS 4-3) and for cold-based ice cover at the Last Glacial Maximum (MIS 2), and instead supports existing regional ice sheet reconstructions. This study demonstrates that a robust, coherent geomorphological framework is fundamentally important to support the validity of detailed geochronological and stratigraphic investigations.
In short, the jury is still out on a range of issues...........
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