Engineers are currently working on the new high-speed rail line that will connect London to Birmingham called HS2. While working on the project, they discovered that the London suburb of Ruislip was once home to an ancient coastline.
The area was being excavated for the new railway.
Paleocene Coastline
An exploratory excavation was being carried for HS2 in Ruislip, West London when samples about 108 feet below the surface unearthed an unknown material that shows the area was swampy during the late Paleocene epoch.
HS2 is calling this layer of black clay, the Ruislip Bed. It was formed from densely wooded marshes at the edge of a sub-tropical area. This discovery was made in an area that is set to become an 8.6-mile tunnel, called the Northolt Tunnel.
Dr. Jacqueline Skipper, a geologist working with HS2, said that the black clay found by the HS2 team differs from the usual sand and gravel found at other sites. This material also had parts of vegetation in it, confirming that it was once part of an ancient coastline in the area.
HS2 has been investigating the ground at 8,000 different locations along the proposed route of the new high-speed railway. This shows that England's geological history differs from what was previously thought.
Ruislip Bed
The Ruislip Bed is roughly between 1.5 to 3 feet thick and is 56 million years old. Skipper adds that this area would have formed during the Paleocene period. This was right at the time when new species were appearing due to the extinction of the dinosaurs. Southern England was covered by the sea.
Skipper believes that the tectonic plates movements were still changing the land around the country. Those movements were responsible for constant changes in the sea levels and the location of England's coastline.
To have such a high amount of preservation is surprising for Skipper, who says that storms can wash away a lot of the previous ground in place, taking information about the area away with it. Even though it was known that at the time the U.K. was a sub-tropical island, this is the first time that a wooded marsh was found.
HS2 has been investigating the ground along the route of the planned railway since 2015. It is the largest ground investigation in U.K. history. Methods used to investigate the ground include drilling into it, gathering samples of soil, and using radar technology.
