Why is the cliff eroding?

The archaeological site at East Wear Bay is eroding into the sea. Although this seems to be happening very gradually when you see it day-to-day on the ground, it is in fact occurring at a fairly speedy rate when we analyse it over time.

Take a look at this photo taken in 1924:

You can clearly see the edge of the cliff as it was in 1924. The yellow line indicates the edge of the cliff back in 2010 - and we know it's retreated further since that line was plotted. You can see that the bathhouse and part of the block to the left of the villa, visible in 1924, has already been lost to the sea. That quite a large chunk of land to go in less than a century!

Can you stop the erosion?

No we can't. Measures have been put in place in the nineteenth and twentieth centuries to slow the rate of erosion, but it will never be completely halted.

Why is it eroding so quickly here but not further on up or down the coast?

Imagine the geology as a stripy ribbon. On the top stripe is the chalk (which makes up the famous White Cliffs of Dover), underneath the chalk is a stripe/layer of Gault Clay, then underneath the clay is the Greensandstone layer. At The Warren the layers rise up meaning the Gault Clay is exposed, then further on into Folkestone the Greensand is exposed. There are links below which have some detailed information about this layering.

Anyway, as the clay is exposed to the sea it washes away much quicker than the sandstone or chalk would. The beach that is directly underneath the cliff offers some protection, but during the winter when the sea gets stormy it reaches the cliff and erodes it away from underneath.

http://www.bgs.ac.uk/landslides/folkestoneWarren.html

http://www.discoveringfossils.co.uk/hastings_fossils.htm

Why not go down to the beach and gather up the archaeological finds then?

We do! The archaeology isn't gracefully slipping into the sea though, it goes through a process called a 'rotational slip' first. A rotational slip is where the soil doesn't immediately go from the top of the cliff to the bottom, instead it (slowly) flips over and gets churned up before landing on the beach some years later (here's a handy link which explains the process a bit better). If you walk along the beach you can pick up Iron Age and Roman finds. You can also pick up a lot of material dumped over the cliff after World War 2 (as a measure to stop erosion) so not everything down there is of great antiquity!

So how far out was the cliff during the Iron Age?

Good question. Our best guess is that it was about half a mile further out during the Iron Age/Roman period, but we are unsure. It is possible that the erosion started when the harbour was constructed in 1810, forever changing the sea currents around Copt Point. The consequence of the change was that the beach quickly eroded back and exposed the fragile clay cliff.

When you look down from our site to the beach you will see an exposed area of Greensand stone. This was originally thought to be the source of the querns but in actual fact would have been covered over during the Iron Age. The people back then would have brought it up from further along the cliff in what is now part of modern day Folkestone. Now that's quite a way to be hauling heavy lumps of stone!

If you want to go to the beach yourself here are a couple of websites with more details:

https://www.thebeachguide.co.uk/south-east-england/kent/the-warren-folkestone.htm

http://www.whitecliffscountryside.org.uk/index.php?id_sec=1132

Don't forget to look out for fossils too!

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