The Last Interglacial Coast Trail

Travels into the Last Interglacial

The Last Interglacial East Yorkshire Coast Trail is a walk in stages that follows the coastline as it was during the last interglacial, about 120,000 years ago, along the eastern rim of the Yorkshire Wolds (approximately like shown in the map above). Holderness is a very young land, geologically speaking. It formed when glaciers retreated after the last glaciation, leaving a layer of boulder clay, sands and gravels on what formerly was a shallow sea cut onto Cretaceous chalk, Holderness Bay. Borehole data has identified a wave-cut platform and chalk cliffs from Hessle, just under the Humber Bridge, via Driffield to Sewerby near Bridlington. 

Approximate location of the buried Ipswichian cliff. From ‘A 3D geological model of the superficial deposits of the Holderness area’.

Another way to see the position of the Ipswichian cliff is to zoom out on a LIDAR map. Beverley is the red dot. Click on the image to enlarge. This image is taken from the ARCHIE website

The walk

I will use public right of way as close as possible to the interglacial coastline in eight 10-12 km stages. As in previous walks, I will write reporting blog posts after each stage, illustrating the fauna and flora I encounter, and include a section on a habitat or lost species characteristic of the last interglacial. I will also be reflecting on changes that are now happening to our climate and environment. An informed, fictional sketch per post aims to recreate the environment of the time.

Stages

1. Hessle to Cottingham. 12.5 km. Hippo.
2. Cottingham to Beverley. 8.3 km. Cave Hyena
3. Beverley to Scorborough. 15 km. Beaver.
4. Scorborough to Hutton Cranswick. 12 km. Brown Bear
5. Hutton Cranswick to Driffield. 7.5 km. Cave Lion
6. Driffield to Burton Agnes.
7. Burton Agnes to Bridlington.
8. Bridlington to Sewerby.

If you want to follow the trail or any of the stages you can use this map:

When, what and where?

The Ipswichian (equivalent to the European Eemian and also known as MIS5e) was a short interglacial, the previous one to that we are living in today, the Holocene. It arrived after one of the hardest glaciations, where ice cover reached the southern half of Britain down to North Norfolk. The transition from glacial to interglacial happened quickly, in a period as short as 3000 years. The period has been dated to between 116,000–129,000 years ago, and its name stems from Bobbit's Hole, a site just outside Ipswich in Suffolk, where the characteristic interglacial flora was described. You might have heard that there was a period of time where hippos, elephants and lions thrived on the old banks of the Thames under what is now Trafalgar Square in London: that was the Ipswichian. The Ipswichian had a warm climate, likely 2-3 degrees warmer than today, but with more seasonality, warmer summers and cooler winters, but lacking extreme cold, so the climate has been compared to the Mediterranean today.

At the time, Britain was an island, likely separated from the continent by a deep canyon, where a huge river collected the waters of the Thames, Rhine and Seine. Some megafauna appeared to have no trouble crossing this formidable barrier, perhaps from further north, but humans, Neandertals in particular, who were living in mainland Europe at the time, didn’t appear to do the crossing, as documented by the lack of evidence in a number of well known sites of the period.

The lost megafauna

‘We live in a zoologically impoverished world, from which all the hugest, and fiercest, and strangest forms have recently disappeared ‘ 

Alfred Russel Wallace

The animals we share this land with are an impoverished assortment of species that somehow has managed to survive the megafaunal mass extinction that took place when modern humans colonised Europe ca. 40,000 years ago. The bigger the animal, the higher the chances it became extinct. Even the surviving species suffered strong declines in numbers. The last interglacial is a glimpse of the last time Britain had thriving ecosystems without humans, during a period with a similar climate than today. Examining this period in time is a way ‘to rage against the shifting baseline’, in Ross Barnett’s words.

The fauna of the period has been reconstructed from fossils found in cave deposits and river terraces. Most large megafauna made the crossing after the previous interglacial, but Neanderthals, then present in mainland Europe, didn’t make it. Britain became an island, packed full or large mammals, but no humans. Schools of Hippos roamed in all the large rivers south of Scotland, and elephants and rhinos browsed in mixed woodland. The combination of Hippo and Straight-tusked Elephant, is a trademark of this period in time. Herds of herbivores browsed or grazed including various species of deer, Fallow Deer Dama dama, Giant Deer, Megaloceros giganteus, and Red deer Cervus elaphus, Aurochs Bos primigenius and Bison, Bison priscus. Wild boar, Sus scrofa would have rooted in woodland glades. These herbivores would have kept grassy areas open along river floodplains, helping maintain a mixed habitat including grassland and woodland. The wider rivers and marshes would have held Hippos, whilst the quieter and narrower streams upstream would have been occupied by Beavers, Castor fiber, contributing to maintaining clearings in the woodland. European Pond tortoises, Emys orbicularis, now ranging to southern France, were present in England, much more northern than their current distribution. Large predators included Cave Lion, Cave Hyena, Wolves and Brown Bear. The Fox, Vulpes vulpes, and the Badger, Meles meles, are the only survivors of this carnivore assemblage in the modern day.

I will be paying attention to the mammals I see along the way.

Why?

If I could time travel, even for a single day, I'd like to visit the British Ipswichian. Time travel is unlikely to happen, but researching that period of time, and using our imagination to try and visualise in an informed way how the environment would have looked then is something we can do, and enjoy. This thought gave me the idea for this walk. The cold stages of the ice age and the megafauna that inhabited them (think Woolly Mammoth) are well known, but other animals that lived when the climate was similar to today's are not so well known (Straight-tusked Elephant, anyone?). In a similar note, the Yorkshire Wolds Way is well known and trodden, but the area covered by this walk, following the East flank of the Wolds is less visited. I hope this trail gives you an excuse to come along and travel to the last interglacial in East Yorkshire!

The map at the top, only a coarse approximation to the position of the East Yorkshire coast, was generated with the website https://flood.firetree.net/.

References

Barnett, R. The Missing Lynx: The Past and Future of Britain’s Lost Mammals. Bloomsbury Publishing, 2019.

Boylan, P. J. The Pleistocene Mammalia of the Sewerby-Hessle buried cliff, East Yorkshire. Proc. Yorks. Geol. Soc. 36, 115–125 (1967).

Candy, I., White, T. S. & Elias, S. How warm was Britain during the Last Interglacial? A critical review of Ipswichian (MIS 5e) palaeotemperature reconstructions. J. Quat. Sci. 31, e2910 (2016).

Currant, A. & Jacobi, R. A formal mammalian biostratigraphy for the Late Pleistocene of Britain. Quat. Sci. Rev. 20, 1707–1716 (2001).

Stuart, A. J. The history of the mammal fauna during the Ipswichian/last interglacial in England. Philos. Trans. R. Soc. Lond. 276, 221–250 (1976)

Stuart, A. J. Mammalian extinctions in the late Pleistocene of northern Eurasia and North America. Biol. Rev. Camb. Philos. Soc. 66, 453–562 (1991)