Scarborough Strata #4

Recently I was reflecting on the trips we ran, and in particular a fossil hunt to Cayton Bay. The trip was a great success, even the weather was good and lots of people found lots of interesting rocks and fossils. But perhaps the most striking thing about the items they found was how many were not originally from the Yorkshire Coast at all. These glacial erratics are part of the evidence left behind by the ice sheets that once covered great swathes of our landscape, and only retreated about 10,000 years ago.

These ice sheets had their origins in Scotland, Scandinavia and many parts of Northern England, and they carried with them rocks from those parts of the world. Then, when the ice melted not only did it leave behind the soft boulder clay that covers much of our coastline, but also rocks and fossils from these far away regions. This means that at places like Cayton Bay where the boulder clay (or glacial till) is exposed to erosion you can find lumps of Shap Granite from Cumbria, bits of Carboniferous limestone from the Yorkshire Dales, quartz from northern Scotland and pieces of rock formed millions of years ago in Norwegian volcanoes.

The glacial erratics are found along all of our coastline, alongside rocks and fossils from the local cliffs, leading to a huge range of material that can be found. This is further added to by other manmade objects, including bricks, water worn glass and concrete. All this variety adds to the sense of excitement when geologising on the coastline, although I have been known to start sounding like a stuck record, repeating the phrases ‘Norwegian volcanic’ or ‘Scottish quartz’ to many excited children hoping they have found a rare gemstone (or more likely something from Minecraft)!

If you are out and about on the coast then why not have a look at our top-ten fossil hunting tips or join one of our walks to find not just fossils but rocks as old as 2 billion years, that are certainly not local.

First produced in Issue 21 of The Scarborough Review

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