HS2 investigators have discovered a sub-tropical coastline which dates back around 56 million years.
The discovery of the previously unknown material was made 33m below the surface following ground investigations from geotechnical firm Fugro, one of nine companies which have a framework contract on HS2’s Phase One ground investigations programme, at a site in Ruislip, west London.
The layer of black clay, which HS2 has named the ‘Ruislip Bed,’ is thought to have been formed from densely wooded marshes on the edge of a sub-tropical sea.
HS2 is investigating ground conditions in the area in advance of the construction of the Northolt Tunnel – a 14km tunnel which will run from West Ruislip to Old Oak Common.
In total, it is investigating the ground at around 8,000 locations along the first phase of HS2, from London to the West Midlands.
Dr Jacqueline Skipper, a geological expert from Geotechnical Consulting Group said: “Although ground investigations regularly take place across the country, it’s really exciting and very unusual to come across a material that no-one has ever seen before. The ‘Ruislip Bed’ discovery is particularly fascinating, as it is a window into our geological history.
“It would have been formed during the Paleocene period, which was a time of intense change, with new animals evolving following the extinction of the dinosaurs. Most of Southern England was covered by a warm sea and this clay helps us to pinpoint where the coastline was.”
After more than one million laboratory tests, the initial ground investigation programme on Phase One will be largely complete by the end of March, 2018. This will be followed by targeted investigations led by HS2’s main works contractors.
HS2 has released a handy video explaining the find:
— RailStaff (@Rail_Staff) March 16, 2018