One of the modern engineering wonders of the world, the Channel Tunnel is the longest underwater tunnel in the world and the third-longest train tunnel in the world.
The Channel Tunnel
One of the modern engineering wonders of the world, the Channel Tunnel is the longest underwater tunnel in the world and the third-longest train tunnel in the world.
Tunnelled straight through the geology of the Cross-Channel Geopark, this extraordinary feat has also permanently reconnected France and Britain after over 450,000 years of separation since the Megaflood.
Not content with being an international engineering marvel, the chalk marl that was dug out to form the tunnel was repurposed to create a new piece of land at the foot of the White Cliffs of Dover which has since flourished into a thriving nature reserve, another of our Geosites – Samphire Hoe.
The unique geodiversity of the Cross-Channel Geopark was vital to the success of the Channel Tunnel project, as the layer of ‘chalk marl’ which sits at the bottom of the chalk, just above the older clay, forms an ideal layer for tunnelling through. Whilst chalk has tiny cracks running through it which allow water to flow through, making it permeable, the Marl layer is impermeable due to it being a mixture of clay, chalk and other materials, perfect for keeping the tunnel from filling with water!
About Geosites
Geosites are sites of geological interest across the aspiring UNESCO Cross-Channel Global Geopark, where people can visit and interact with our geological heritage. This wide range of sites will offer varying opportunities and values including cultural, heritage, scientific, educational, and aesthetic.
About the aspiring UNESCO Cross-Channel Global Geopark
Hundreds of thousands of years ago a catastrophic flood swept away the chalk ridge connecting Dover and Calais, carving out the white cliffs of Dover and starting Britain’s history as an island.
Did you know the Kent and French coasts are actually still connected today by the layer of chalk which runs below the Channel?
In celebration of the chalk and the channel, we are working to secure UNESCO Cross-Channel Global Geopark status for the Kent Downs National Landscape together with our neighbouring protected landscape in France; the Parc Naturel Regional des Caps et Marais d’Opale.
The Geopark will include both the protected landscapes and the Channel connecting them, recognising and celebrating the geological connection between us.
