Engineers Discover West London Was Once Home To A Verdant, Subtropical Coastline 56 Million Years Ago

The discovery occurred during initial investigatory work for the future Northolt Tunnel.

A 56-million-year-old subtropical coastline has been discovered in West London.
Jack Taylor / Getty Images

The discovery occurred during initial investigatory work for the future Northolt Tunnel.

In Ruislip, West London, engineers at HS2 Ltd who have been busy building the new high-speed railway have stumbled across the remarkable discovery that this region was once a lush, subtropical prehistoric coastline 56 million years ago. During recent excavations, a strange type of material was found 33 meters beneath Ruislip which would indicate that the area known as the Ruislip Bed once contained wooded marshes at the time of the late Paleocene epoch.

According to The Guardian, geologist Dr. Jacqueline Skipper explained that black clay was found during construction rather than the normal gravel and sand which they had expected to find.

“When we looked at it in detail, instead of the usual sand and gravel we had a black clay, which not only had bits of vegetation in it but also showed evidence of extreme weathering of what would have been sand and gravel there before. Suddenly you have got evidence that this is actually the coastline.”

Describing what this region of West London would have looked like 56 million years ago, Dr. Skipper described what would have been a paradisiacal coastline filled with beaches, swamps, and marshes.

“You have got a three-dimensional vision of what was going on. We’ve got trees, we’ve got animals living in the trees, we’ve got marshes, we’ve got swamps and we’ve got very nearby beaches.”

Engineers working with HS2 have been investigating the different ground locations at 8,000 sites that are scattered between London and the West Midlands, and the area in which the black clay was found was initially discovered while workers were trying to ascertain what the ground conditions were like at the future location of the Northolt Tunnel, as Heritage Daily report.

The black clay was found in several different locations around Ruislip, West London, although in other areas close to where the clay was found, sand and gravel were also spotted at roughly the same depth, which would show that these areas of marshland were once part of an ancient subtropical coastline.

There would have been no polar icecaps 56 million years ago, and back then the coastline would have shifted simply due to slippage of tectonic plates. India would have been moving much closer to Eurasia at this time while the Atlantic Ocean slowly began to grow into a much more open expanse, and this would have accounted for the different fluctuations in the levels of the sea as well as the shifting position of the coastline of Britain itself.

However, the discovery of the Ruislip Bed was quite a surprise, according to Dr. Jacqueline Skipper, because in locations where you find the sea level has risen you don’t normally find sediments that are as well-preserved as they have been at this site.

“If you have sea level rise you also have a lot of storms and reworking of the previous sediments, so you don’t always get that much information.”

As geologist David Entwistle attests, discovering the black clay in West London was an extremely rare find, and one which nobody would have ever expected.

“About 56 million years ago the UK was a subtropical island and the southeast of England lay on the western edge of a sea that extended eastwards at least as far as Poland. This area was a low-lying area, meaning that small changes in sea level resulted in large changes in the land covered by the sea, which, at its maximum extent, covered much of southern England.”

Entwistle also noted that considering the marsh in this area would only have been around for a brief period of time, it is nothing short of miraculous that it was even found.

“This is the first time that a deposit formed by a local densely wooded marsh of this time has been recognized in England. The woodland marsh may have only existed for a relatively short time before river deposits covered it.”

Further investigation at this site continues so that scientists can learn more about this area of Ruislip, West London, which was once the home to a 56-million-year-old subtropical coastline and marshes.