The Arcturus Glacier surge

 

Above we see two photos of Malmbjerget in East Greenland.  The "red mountain" contains the biggest molybdenum resource in Europe, and is currently the scene of a massive open pit mining proposal with a capital investment budget of over a billion US dollars.  The proposers, Greenland Resources Inc, are currently trying to raise an initial USD 820 million, but full consents are in place, and there is a big documentation available re project proposals, environmental assessments etc.  The project is so vast that we are talking in effect of the industrialisation of the Werner Mountains and the Mestersvig area to the north, on the shore of Kong Oskars Fjord.

The reddish coloured outer tip of the mountain, between the two glaciers, will be completely removed by the working of the open pit, and there will be vast infrastructure developments as shown on the map below.

The figures are mind-boggling.  203 million tonnes of waste will be stripped during the working of the open pit, and 115 million tonnes of ore will be taken out, initially stored and then taken out to be milled. Of this, 75 million tonnes of waste and low grade ore will be stored in huge stockpiles on the surfaces of the Schuchert and Arcturius Glaciers.  Surface roadways for heavy plant traffic will be partly on the glaciers themselves and partly on adjacent valley sides.  A 10 km tunnel may or may not be built under the Mellem Pass, to connect the open pit to the valley to the north -- it is planned to have an entrance somewhere near Kolossen.  Also running across the mountain range will be an aerial transporter system about 26 km long, designed to export 35,000 tonnes of ore per day.  No supporting towers can be built on the glaciers, so there will have to be at least two very long spans, one across the Arcturus Glacier and the other across the Mellem Glacier -- and that means at least four massive towers.

A glaciological study of the Arcturus Glacier, designed to understand the likely impacts of this mining / quarrying proposal, wasa published in 2009:

 Glaciological investigations at the Malmbjerg mining prospect, central East Greenland. 

https://www.researchgate.net/publication/242584915_Glaciological_investigations_at_the_Malmbjerg_mining_prospect_central_East_Greenland 

The 2008 measured velocity is 18 m per year. Quote: This can be compared with the present-day average velocity of 22 m per year obtained from feature tracking on two orthophotographs from 2005
and 2007, and using theoretical results relating surface velocity with mean velocity over a cross-section of parabolic shape (Paterson 1994). Considering the uncertainties involved, we conclude that no imbalance has been detected to suggest that a surge of Arcturus Gletscher will occur in the near future.

Clearly that assumption was unwise, because the two photos at the head of this post show that the Arcturus Glacier has recently surged.  I have no dates for the photos,  but the lower one was clearly taken more recently than the upper one.  The surge has carried the snout of the Arcturus Glacier into and onto the surface of the Schuchert Glacier.

Here is a Google Earth 3D representation, dated 17 July 2025:

There are actually two Arcturus Glacier surge loops -- the outer one is not far from the present snout position of the Schuchert Glacier.  This suggests to me that Arcturus Glacier is more active than the Schuchert Glacier, and that it has quite a high surge frequency.

I'm contacting the glaciologists who undertook the Arcturus Glacier study -- but it seems to me that the complexities of the local glaciology have not been adequately taken into account by the proposers of the  open pit project.  The knock-on effects of the major environmental disruptions involved in storing 75 million tonnes of waste and low-grade ore on the surfaces of two glaciers with known surging behaviour are therefore underestimated.

This behaviour will also affect the stability (and hence the cost) of thr transport roadways built on the surfaces of the two glaciers.

I have further concerns about the proposals to build a 1 km airstrip capable of dealing with Hercules transport aircraft on the expansive area of ice-cored moraines beyond and to the west of the Schuchert Glacier snout.  In the published reports there is NOT an adequate assessment of the civil engineering challenges presented.

Watch this space.........

The Long Walk -- East Greenland 1962

This has nothing to do with Stonehenge nor the bluestones, but I have just published it on YouTube, and it's worth sharing............

It's always fun to reminisce about the Good Old Days.  The bonds of friendship that we developed as young men on that expedition came out of shared aspirations and shared hardship.  The walk into our fieldwork area was the toughest thing I had ever done as a tender 21-year-old, and I still recall the misery and the mosquitoes.  But it was all worth it, and our fieldwork area -- Kjove Land -- was a polar paradise.

The work that Dave Sugden and I did on the raised marine features -- published in the Geographical Journal in 1965 -- was our first serious research project with important results, and the paper is still widely cited to this day.

And the expedition triggered my love of glacial geomorphology, which (as readers of this blog will know!) is still a powerful motivation.

https://www.researchgate.net/publication/262414669_The_Raised_Marine_Features_of_Kjove_Land_East_Greenland#fullTextFileContent

Staunings Alps, East Greenland

 

In the Staunings Alps of East Greenland there is true alpine topography.  The landscape of small icefields, short steep glaciers and jagged mountain peaks is very different to the  plateau and trough landscape that dominates most of East Greenland........

These pics are taken from a long video made by one of the passengers on a special low-level (5,000m) charter flight to the North Pole........

The mystery of MIS-3 and MIS-4

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 potential
Robert Dinnis
Jnl of the Royal Anthropological Institute
First published: 20 August 2025, pp 1-17
https://doi.org/10.1111/1467-9655.14313

Abstract
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).

==================

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.

========================

The paper by Rolfe et al 2012:

https://brian-mountainman.blogspot.com/2014/07/lundy-island-and-lgm-dilemma.html

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

http://dx.doi.org/10.1016/j.pgeola.2017.06.005

A B S T R A C T

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.

https://brian-mountainman.blogspot.com/2017/12/more-fun-and-games-on-lundy-island.html

In short, the jury is still out on a range of issues...........

Cosmogenic nuclide dating of rock surfaces in West Wales

BRITICE map showing the suggested exposure time since ice sheet inundation across the UK.  Note that in Pembrokeshire, it is suggested that north Pembrokeshire was glaciated during the LGM, but south Pembrokeshire was not.  That is the hypothesis that needs to be tested.

It's good to be a part of this research group.  This is Alissa's short presentation for a recent geomorphology conference in New Zealand.  Alissa, Prof John Hiemstra, Prof Iain Robertson and I collected numerous rock samples in early June which are currently being processed prior to analysis.

---------------------------

Using multiple cosmogenic nuclides to constrain the British-Irish Ice Sheet in Pembrokeshire (Wales) during the Last Glacial Maximum (LGM) 

Dr Alissa Flatley, Dr John Hiemstra, Dr David Fink, Dr Keith Fifield, Dr Brian John, Dr Reka Hajnalka Fülöp


Dr Alissa Flatley, February 5, 2026


There is considerable debate surrounding the southern limit of the British Irish Ice Sheet (BIIS) particularly in Pembrokeshire, Wales. This is partly due to differing interpretations of the sedimentary and geomorphic record, but a lack of detailed geochronology of regional LGM ice extent is also a major barrier. In Pembrokeshire, proposed LGM ice limits trace the northern flanks of the Preseli Hills suggesting that southern Pembrokeshire may have remained ice-free. However, significant uncertainty remains regarding the interaction between the Irish Sea Ice Stream and the Celtic Sea lobe, and the maximum extent of the Welsh Ice Cap. This project addresses these uncertainties by using multiple in-situ cosmogenic nuclides 10Be, 36Cl and 14C in lithologically varied samples across Pembrokeshire to further our understanding of the region's deglaciation history. 

Cosmogenic nuclides can determine the maximum time a bedrock surface or glacial erratic has been exposed. However, it is possible that exposure may have been intermittent over this time (e.g. complex exposure history) or that the previous exposure signal has been retained (i.e. it has not been removed through erosion under the most recent ice advance), an effect called ‘inheritance’. The issue of nuclide inheritance within samples can yield anomalously ‘old’ exposure ages common in more erosion resistant lithologies prevalent across the Pembrokeshire coastline and therefore it acts as a key scientific constraint surrounding LGM ice sheet reconstruction. Cosmogenic nuclides with a short half-life (e.g. in situ 14C) will be integrated into the project to date short timeframe changes in ice dynamics. For glaciations < ~ 20-30ka, in situ 14C, with a half-life of 5.7 kyr, can be used in conjunction with longer-lived nuclides such as 10Be to identify inherited signatures in samples. This project will provide a much-needed understanding of ice sheet dynamics across the region, advancing understanding of complex landscape processes.

Book of abstracts: 3ce3bf9f40984a6ab3bfc62b2a194cd5.

================================

Iain, John and Alissa sampling bedrock at one of the north Pembrokeshire sites.

Dr Iain Robertson -- about to take a pXRF reading on the Abermawr erratic boulder

The other scenario.  In this BRITICE model (from Clark et al, 2022) LGM ice fills the Bristol Channel and affects the coasts of Cornwall, Devon and Somerset.  Note that this reconstruction applies to the Late Devensian only -- it does not preclude a more extensive ice cover during earlier glacial episodes. 

The proposed ice-free corridor at the time of the LGM -- as featured in numerous publications.  This is what the new project seeks to test through a substantial sampling programme.

The ice-free corridor as proposed in some of the early BRITICE work..........

A more realistic proposal for the extent of LGM glaciation in the South Wales / Bristol Channel arena.  Here the inner reaches of the Bristol Channel are essentially ice-free, with the depression occupied instead by a large pro-glacial lake..........

For a detailed study of the problem, see this paper from 2023:

https://www.qra.org.uk/mp-files/qn158_1_late-devensian-ice-free-corridor-in-pembrokshire.pdf/

John, B.S. 2023. Was there a Late Devensian ice-free corridor in Pembrokeshire? Quaternary Newsletter 158, pp 5-16.

Above pics, thanks to Alissa.  John and Iain at work at Maiden Castle, Trefgarn Gorge, in June 2025.

Me at the Roch Castle rhyolite crag.  Thanks to Alissa for the pic.  Don't worry --we had permission.......!!

The Meaden Cobble -- probably from Somerset?

The Meaden Cobble -- a clast of dark-coloured Carboniferous Limestone, probably from one of the Black Rock Limestone outcrops in Somerset

Further to my earlier post, we now have more information on the "Meaden Cobble" found near the West Kennet long barrow. 

https://brian-mountainman.blogspot.com/2026/01/a-black-limestone-cobble-from-west.html

In the opinion of my colleague John Downes: 

 "I think that it is likely to be a bit of Black Rock Limestone from the Mendip region. It clearly has a substantial proportion of carbonate mud and hand lens examination shows a grain supported structure which suggests a packstone according to the Dunham classification. Possibly fragmented crinoids and shell fragments. The network of calcite micro veining shows the rock has been minutely fractured during orogenesis and subsequently calcite has been precipitated. I scraped a small vein with a penknife which produced a powder. Hence this is not quartz which would have been too hard to scrape. I could not get much reaction with white vinegar but then the specimen is muddy and the vinegar was probably not strong enough to produce effervescence. A thin section examination might be more revealing." 

THE BACKGROUND


• Black Rock Limestone: well-bedded, poorly sorted, dark grey to almost black crinoidal limestone with chert nodules. Clifton Down Group: calcitic and dolomitic, oolitic and bioclastic sediments. Hotwells Group: massive fine-grained, smooth-textured calcitic muddy limestone with corals, ooliths, and brachiopods.

Possible locations: Burrington Coombe, Avon Gorge, Cheddar Gorge

It occurs in Pembs too:

Pembrokeshire, the Black Rock Limestone (technically the Black Rock Limestone Subgroup) occurs primarily in the southernmost part of the county. It is part of the broader Pembroke Limestone Group and is well-exposed along several key coastal areas:
• South Coastal Cliffs: It forms the base of the spectacular cliffs between Tenby and Frainslake Sands. You can see it at major landmarks like St Govan’s Head, Stackpole Head, and Lydstep Point.
• Tenby Area: It is famously associated with the Blackrock Quarries near Tenby(located near what is now Kiln Park), which historically supplied limestone to local lime kilns.
• West Angle Bay: The rocks here include fine-grained grey and dark limestones (~350 million years old) that are part of this succession, containing abundant fossils of crinoids and corals.
• The "North Crop" Outcrop: A narrow, intensely quarried band of this limestone runs inland from Carmarthen Bay through areas like Ludchurch and Templeton, eventually narrowing and dying out south of Haverfordwest.
• Caldey Island: The northern half of Caldey Island is a geological extension of the limestone bands found on the mainland near Tenby and Penally.
Identifying it in the field:
In Pembrokeshire, while the weathered surface of these cliffs often appears light grey, the "fresh" or broken surfaces are typically much darker or black due to their organic content. If you visit the Castlemartin Firing Range (home to the Green Bridge of Wales), you are walking directly on these Carboniferous formations.

Gower too…….

In Gower, the Black Rock Limestone (specifically the Black Rock Limestone Subgroup) is exceptionally well-exposed along the south coast, particularly where the oldest Carboniferous rocks are brought to the surface by geological folds.
It occurs in several prominent locations:
• Rhossili and Worm's Head: The jagged rocks on the beach below the Coastguard Lookout and the causeway leading to Worm's Head are made of this limestone. Here, you can see the strata dipping steeply as they form the "core" of the local anticlines (upward folds).
• Three Cliffs Bay: It forms the striking, sea-dipping slabs on the western side of the bay. This area is a type section for the Penmaen Burrows Limestone Group, which is the local name for the sequence that includes the Black Rock Limestone.
• Mewslade and Fall Bay: While the upper cliffs are often younger formations (like the Gully Oolite), the base of the cliffs and the surrounding foreshore between Mewslade Bay and Fall Bay contain exposures of this subgroup.
• East Gower: It crops out along the limbs of the Cefn Bryn Anticline and forms much of the dramatic coastline from Oxwich Point through to Mumbles Head.
Notable Features in Gower:
• Fossils: These rocks are famously bioclastic, containing abundant remains of crinoids and brachiopods like Chonetes.
• Calcite Veins: At Rhossili, the dark limestone is often cut by bright white calcite veins and red haematite infills, creating a high-contrast "striped" appearance on the rock face.
• Superficial Colouring: Interestingly, while the rock is naturally dark grey/black, researchers note that the intense black appearance on some Gower cliff faces is often enhanced by a bio-film of black lichen or cyanobacteria.

Pembs differences — deeper water and so more detrital material / darker colour?

The fossil assemblages in the Black Rock Limestone of Pembrokeshire and Somerset are remarkably similar because both regions were part of the same shallow, tropical marine shelf during the Lower Carboniferous period.
However, there are subtle differences in preservation and diversity due to the specific local environments (facies) at the time of deposition:

The Core Similarities
In both locations, the limestone is bioclastic, meaning it is primarily composed of the broken remains of marine organisms. You will find:
• Crinoids: These "sea lilies" are the most abundant fossil in both areas, often occurring in such high volumes that they form "crinoidal packstones".
• Brachiopods: Rugose and chonetid brachiopods (like Rugosochonetes vaughani) are standard index fossils for this layer in both regions.
• Zaphrentoid Corals: Small, solitary horn corals (e.g., Zaphrentites delanouei) are characteristic of the lower parts of the succession in both Somerset and Pembrokeshire.

So for the moment we have a pretty robust suggestion from two geologists as to the possible origin of the cobble. The fossils may hold the key. We seem to be looking at impressions rather than actual organic or mineralised remains, but I will see what assistance we can get from experts in the field……….

Could this be a glacially transported clast?  Yes, it is possible.  Long ago Kellaway claimed that he had seen ancient glacial deposits near Bath, and that he had also seen a degraded diamicton on the edge of one of the stone quarries near Nunney and Frome.  If the Meaden Cobble really is an erratic, it could have been transported by ice travelling west - east, or SW to NE.  

The West Kennet granidiorite boulder (or boulders) could have travelled in the same direction -- but this would go against the speculation by Ixer and Bevins that it has travelled southwards from a source in NE England.    They and other colleagues assume that the boulder has come from Cunyan Crags. but that is based on the questionable assumption that erratics always come from upstanding craggy outcrops.  That goes against the current thinking in glacial geomorphology.......

There is certainly a puzzle here, largely because of the difficulty of discerning ancient ice movement directions in the field., where things are dominated by evidence from the LGM.

Watch this space.........

The Kokelaar Guide to erratic pebbles

The info below is extracted from the following excellent resource: 

https://kokelaargower.com/towards-stonehenge-the-anglian-glaciation-of-gower/

The pebbles illustrated below have all come from Gower raised beaches -- derived from many different places.  I'm particularly struck by the Ramsey Island connection -- as flagged up here by somebody who knows the igneous rocks of that island particularly well.  Some of these look very familiar -- I have seen them in abundance on the Pembrokeshire beaches, and also on Flat Holm in the middle of the Severn Estuary.

Silicic volcanic and shallow-intrusive rocks -- probably mostly from Ramsey Island

Mafic intrusive and extrusive rocks -- mostly from NW Pembrokeshire and maybe Skomer island

Diverse igneous erratics -- some from North Pembrokshire coast, Skomer and possibly Scotland

Silicic and intermediate intrusive rocks -- from Ailsa Craig and other distant sources

For further details on the provenances and rock types, please consult Peter's blog -- link as above.

For comparison, here are some of the erratic pebbles collected on Flat Holm in 2014:

The most abundant beach pebbles on the island are made of Carboniferous limestone and ORS, but igneous pebbles are also found on every beach on the island