London was once criss-crossed with rivers and the Crossrail route bisects a number of these ancient waterways.
At Royal Oak, in west London, we have discovered a 68,000 year old channel, close to the route of the historic River Westbourne. Excitingly, the ancient waterway contained a large collection of animal bones from species that are now extinct in the British Isles, including prehistoric reindeer and bison. The bison bones are, Bison priscus; which was one of the most widespread large mammals in the Pleistocene period. The animals lived throughout Europe and Asia from at least 500,000 years ago. As the climate warmed these animals, along with the mammoth, disappeared from Britain and Europe.
The River Westbourne once rose in Hampstead and flowed south to enter Hyde Park, at the Serpentine, before passing through Chelsea to meet the Thames. In the early 1800s the River Westbourne was diverted into an underground brick pipe called the Ranelagh Sewer.
Humans moved into and out of Britain as the ice ages came and went during the Pleistocene era. Ice was so far south it would have been too cold to live in Britain. The age of the ancient channel coincides with a period when people migrated back into northern Europe.
Could the bones we found at Royal Oak portal be the result of hunting? Initial observations suggested that some of the bones had small marks on them. These may have been tool marks. Archaeologists are able to tell the difference between tool marks and other types of wear. When the bones were examined with high power microscopes the marks were found to be made by gnawing carnivores, possibly wolf or bear, and trampling.
It is likely that the animals were washed away in flood waters and then scavenged by carnivores. Collections of animal bones were no doubt a common sight in this turbulent landscape and were moved again in further floods, dispersed around the channel banks and edges, broken by trampling and then buried over with soil sediments until finally re-exposed in our excavations.
We have also investigated the River Tyburn channel at Bond Street, a small tributary of the River Fleet at Farringdon believed to be Faggeswell Brook and the Walbrook River that once divided the city of London.