Mammoths on the festive menu

 

Here we go again!  Another pre-publication TV docudrama, this time on the subject of the mammoths and other remains found in a gravel pit near Swindon. It's on Dec 30th, on BBC1, and it's called "Attenborough and the Mammoth Graveyard".  There is, of course, vast pre-broadcast publicity, including a piece in yesterday's Observer:

https://www.theguardian.com/science/2021/dec/19/five-ice-age-mammoths-unearthed-in-cotswolds-after-220000-years

https://inews.co.uk/culture/television/attenborough-mammoth-graveyard-ice-age-discovery-swindon-archaeologists-1358627

Actually, I rather trust David Attenborough, who has a great knack of communicating scientific discoveries in an accessible and reliable way, without going off into flights of fancy.  So, fingers crossed that the programme will be informative, entertaining and well grounded.

The dig at this gravel quarry site has been coordinated by DigVentures, which is a social enterprise company, rather than by one of the university departments of archaeological trusts.  One of the leaders of the project is Lisa Westcott Wilkins.  The discoveries in the pit were first investigated by two amateur fossil hunters, Sally and Neville Hollingworth.  One of the lead investigators is Prof Ben Garrod from the Univ of East Anglia, who has written extensively on the woolly mammoth.  A number of other university personnel have been brought in to help with specialist analyses. 

https://digventures.com/projects/mammoth-graveyard/

Five mammoths, a steppe bison, a brown bear, and rumours of other animal remains as well -- and in addition flint tools including a Neanderthal hand axe.  Some of the bones appear to have butchery marks on them -- so whether the animals were hunted, or just discovered, butchered and used for food, bones, skins and other body parts will no doubt be revealed. From one of the reports:

On top of the mammoths themselves - two adults, two juveniles and an infant that are thought to be 220,000 years old, they have also found giant elks, tiny creatures like dung beetles and snails and even seeds, pollen and plant fossils, as well as human tools like an axe.

What interests me most of all here is the context. These remains were found in a Hills Group gravel pit to the north of Swindon about four years ago, in an area of mud and other fine-grained sediments apparently beneath one of the Thames terraces.  The precise location has not been revealed.  However, the history of the Thames terraces is pretty well known, and no doubt we will find out eventually where the finds fit into the glacial - interglacial sequence.  However, it has been revealed that these finds are around 225,000 years old. That's surprisingly early, given that most woolly mammoth finds date from the Devensian glaciation, around 20,000 years ago. The press release refers to MIS7 as the age of the finds.  That means they slot into a very mysterious interglacial episode now referred to as the Aveley Interglacial, between the Early Wolstonian glacial phase and the Saalian glaciation of Northern Europe.   But some authorities think that the late Wolstonian is the equivalent of the Saalian, which means that the Aveley Interglacial (between 243,000 and 191,000 years ago) may have been a time of oscillating interstadial climate.  As I have said in many earlier posts, the Wolstonian glacial episode remains very difficult to decipher.

The sequence of climatic changes:

MIS 2 – 29,000 yrs BP  Late Devensian -- peak glaciation.   COLD
MIS 3 – 57,000  mid-Devensian
MIS 4 – 71,000  Onset of Last Glacial Period / Weichselian / Devensian / Wisconsin in North America

MIS 5 – 130,000   Eemian interglacial, or Ipswichian in Britain -- many substages. WARM

MIS 6 – 191,000  Illinoian glacial in North America, Saalian in northern Europe and ?? Late Wolstonian in Britain)

The mammoth and other finds now announced are c 225,000 years old.

MIS 7 – 243,000 (Aveley Interglacial in Britain)  WARM

MIS 8 – 300,000 Early Wolstonian in Britain.    COLD

MIS 9 – 337,000 (Purfleet Interglacial in Britain)  WARM 

MIS 10 – 374,000   COLD

MIS 11 – 424,000  Hoxnian Interglacial in Britain   WARM

MIS 12 – 478,000 Anglian Glacial in Britain, Elster glaciation in northern Europe.  COLD

We still do not know how the location of these finds fits into the pattern of glaciation in this area.  There is a strong possibility that the Anglian ice extended further south than Swindon, but where was the Wolstonian ice edge, and when did it reach its maximum position?  Do these finds relate to a time of deteriorating climate towards the end of the Aveley interglacial or interstadial phase, when tundra was expanding and mammoths and other steppe animals were moving into terrain which had previously been characterised by taiga or cool temperate forest?  Or was it the other way round, with steppe animals moving north as the climate ameliorated?

The steppe mammoth was enormous -- but the individuals examined from this site appear to be somewhat smaller than those which ranged across the steppes hundreds of thousands of years earlier.  They may have  grown smaller over time -- suggesting that they were von the way out, probably down to changing environmental conditions and maybe increased competition for resources.  They are thought to have been the ancestors of the beloved woolly mammoth which thrived during the most recent episodes of the Ice Age.

All will be revealed.  Whatever the climatic interpretations may be, I'm sure there will be relevance for what happened a bit further south, on Salisbury Plain.

 PS.  Thanks to Tony for drawing attention to this interim report:

https://www.winchester.ac.uk/research/our-impactful-research/research-in-humanities-and-social-sciences/research-projects/the-mammoth-graveyard-quarry/?

THE MAMMOTH GRAVEYARD QUARRY

Extract:
The fossils are mostly of steppe mammoth (Mammuthus trogontherii), a species inhabiting open grassland habitats across Eurasia before 200,000 years ago. These remains were mostly uncovered in the base of a former river channel, possibly of what is now the Thames, and usually lying against large boulders. These boulders were mostly of a rounded shape, indicating they had been moved along the bed by very rapidly flowing water. Overlying the mammoth bones were fine gravels and sands. These were also deposited in a channel, but one in which water velocity was much lower, and certainly too slow to move the fossils. Given that the bones are unabraded, they cannot have moved far. It therefore seems likely that the mammoths died close to or within the channel and that subsequent movement was sufficient only to lodge them against the boulders.

Samples taken from the sands and gravels have been analysed to date the site as well as to recover plant and invertebrate bones. Measurements made using the Optically Stimulated Luminescence (OSL) technique by Prof. Phil Toms at the University of Gloucestershire show that the mammoths died around 225,000 years ago. This age is significant as it coincides with a warm episode of the Pleistocene geological epoch (the period from 2.6 million to 11,700 years ago, commonly called the 'Ice Age'). Indeed, the modern range of beetles found in samples from the sands and gravels, and studied by Dr Enid Allison at Canterbury Archaeological Trust, suggests they formed in a climate only slightly cooler than today. Nevertheless, and unlike now, the landscape around the mammoth graveyard would have been open grassland lacking in trees, as evidenced by the ecological preferences of molluscs (snails) studied by Dr Matthew Law of L-P Archaeology. In other words, the landscape would have been perfect grazing for the steppe mammoth.