Under the Railways

By Amy Walsh

One giant trench through the countryside. What could we discover?

Eurostar service on the High Speed Rail 1 line
Image copyright UNKIEPAUL / Paul Johnston used under a CC BY-SA 2.0 Licence from Wikimedia.

The announcement of Phase One of the High Speed 2 (HS2) railway in the UK in 2010 sparked much apprehension, controversy and debate amongst members of public and the scientific community alike. The carving of this 140-mile railway line through the British landscape from London to Birmingham poses many threats and challenges to the environment. But the project also provides a platform for scientists to investigate our buried past and in turn, mitigate the risks of construction, ensuring we record whatever is destroyed in its path.

In this blog, we will take a journey through the opportunities provided by HS2 that lie within the fields of geology, palaeontology and archaeology – all of which fall under the multi-disciplinary study of Quaternary Science1.

Stop 1- Setting off on a journey deep into Britain’s past:

The Quaternary is the most recent geological time period, encompassing the past 2.58 million years. It is comprised of two geological epochs – the Pleistocene (2.58 million- 12,000 years ago) and the Holocene (12,000 years ago to present day)2. Unfortunately, the patchy nature of fossilised deposits from this epoch means many are still buried deep below the surface of our landscape.

Sediments from former rivers and lakes were laid down across the landscape as the Quaternary climate shifted between alternate warm and cold conditions, but once deposited they were extremely vulnerable to erosion or destruction, meaning very few remain intact today.

The excavations for HS2 will involve digging deeper into British sediments than your typical house-build or road construction works, presenting us with an opportunity to investigate significantly older periods of time than have previously been studied.

Stop 2- What might we find? Highlights along the route:

Past discoveries made by Victorian excavators, quarry workers, and more recently by large-scale construction projects, have yielded some exciting finds and helped to further our knowledge of the Pleistocene.

Fossilised creatures known from the Pleistocene so far include extinct species such as the Woolly Mammoth (Mammuthus primigenius) and the Woolly Rhinoceros (Coelodonta antiquitatis). There is also evidence that the distribution of extant (living) species differed to their modern ranges as the climate oscillated between hot and cold spells. Species such as Lion (Panthera leo), Hippo (Hippopotamus amphibius) and Spotted Hyena (Crocuta crocuta) were once found roaming the landscapes of Britain3.

Ice Age fauna of Europe by Mauricio Antón
Image copyright Mauricio Antón from Caitlin Sedwick “What Killed the Woolly Mammoth?”. PLoS Biology 6 (4): e99. DOI:10.1371/journal.pbio.0060099 used under a Creative Commons Licence from Wikimedia.

Alongside potential discoveries of fossilised plants and animals, we may even find archaeological artefacts such as stone tools from Britain’s earliest human inhabitants.

Stop 3- Making sure no one has to pull the emergency lever:

There is no simple tool to enable the identification of significant Pleistocene age fossils along the line – the term ‘needle in a haystack’ comes to mind. Nevertheless, as scientists, it is important to draw upon several lines of existing knowledge to help predict areas of potential interest and prevent their destruction.

Firstly, river and lake deposits are often a rich source of fossils and artefacts. This is because water is a vital resource and animals and humans typically lived (and died) close to water bodies. Moreover, lakes and rivers often have physical and chemical conditions at the time of deposition that enhance the likelihood of fossil preservation.

Secondly, local records from collections held in museums and Historical Environment Records (HER) for the counties through which the route passes have allowed HS2 to compile extensive lists of important finds. More often than not, finds of Pleistocene age in the vicinity of the route were stumbled upon by chance, meaning that information surrounding the circumstances of their discovery is often not well documented.

Mammoth molar held in Bucks County Museum Resource Centre
Image copyright Amy Walshe

Recognition of the importance of these rare yet valuable sites within HS2 frameworks is further complicated by the lack of existing designated protected status, thereby limiting the potential for investigations to be conducted in advance of construction. Unlike other parts of Britain where deposits of Quaternary age are well known and have legal protection, what lies under the path of HS2 is largely a mystery. What this means is that it is important for HS2 contractors to work closely with specialist bodies to ensure that appropriate measures are taken if a discovery is made to either preserve the site, or record and remove the finds.

Stop 4- All change here:

Recent construction projects in Britain such as the Channel Tunnel, High Speed Rail One (HS1) and Crossrail have all played an important role in furthering our knowledge of the Pleistocene and informing HS2 mitigation frameworks. They have also borne some exciting Pleistocene-age finds.

A significant discovery dating back to approximately 400,000 years ago was unexpectedly made at Ebbsfleet in Kent during the construction of the High Speed 1 rail link from the Channel Tunnel to London in 20034. Construction works were halted to begin a controlled excavation at the site over 8 months in 2004.

Here, a unique find was made of an extinct straight-tusked elephant (Palaeoloxodon antiquus) surrounded by flint tools suggestive of butchery, and received widespread media attention.

Similarly, the discovery of an ancient 68,000-year-old river channel at Royal Oak in West London, during the construction of Crossrail, attracted public interest. This ancient waterway contained a large collection of animal bones including Pleistocene reindeer (Rangifer tarandus), and bison (Bison priscus) – one of the most widespread large mammals in the Pleistocene period.

In 2012, Crossrail ran an educational outreach programme and exhibition called ‘Bison to Bedlam: Crossrail’s Archaeology so far’ which provided opportunities for local communities, students and non-professionals to engage in the research generated by the construction works.

Final destination?

For now, we must sit tight and wait for updates from the construction works of HS2 but in the meantime, a growing body of publications provide detailed conservation frameworks to ensure these sites are protected and the profile of the Pleistocene continues to be raised by remarkable science. Let’s hope that’s enough to protect the remains of Britain’s Pleistocene past.


  1. Buteux, S., Chambers, J. and Silva, B. (2009) Digging up the Ice Age: Recognising, recording and understanding fossil and archaeological remains found in British quarries. Oxford: Archaeopress.
  2. Gibbard, P., Head, M., Walker, M. and The Subcommission on Quaternary Stratigraphy (2010) ‘Formal ratification of the Quaternary System/Period and the Pleistocene Series/Epoch with a base at 2.58 Ma’, Journal of Quaternary Science, 25 (2), pp. 96-102.
  3. Currant, A. and Jacobi, R. (2011) ‘The Mammal Faunas of the British Late Pleistocene’, Developments in Quaternary Science, 14, pp. 165- 180
  4. Wenban-Smith, F. F., Allen, P., Bates, M. R., Parfitt, S. A., Preece, R. C., Stewart, J. R., Turner, C. and Whittaker, J. E. (2006) ‘The Clactonian elephant butchery site at Southfleet Road, Ebbsfleet, UK’, Journal of Quaternary Science, 21, pp. 471–483.
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