The Whin Sill

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While I have been 'curating' - she says grandly - photos to put on this blog, I've been reminiscing about when I took some of them.  Take this one, for example:  I was on an Open University geology summer school (SXR260, anyone?), and it was the first time I had been to Teesdale (County Durham, in northern England).

One of our field trips was to see the Whin Sill (a lens-shaped igneous rock intrusion that took place in the late Carboniferous). There's an amazing exposure of the sill here at High Force Waterfall!  I can just imagine the heat of the magma as it forced its way through the country rock, and the cracking, creaking and groaning as it happened.  The basalt columns, by the way, are the same structures formed by the dolerite cooling that you see at Fingal's Cave and the Giants' Causeway.  Further along the Tees, at Low Force, you can walk across the exposed tops of such columns to see the hexagonal shape of the columns from above.

I was using my dirt-cheap APS camera here; it did me proud.  The only time I've been back since then, I forgot to pack my (now-digital) camera!  This was in the years BS (Before Smartphones) so I sadly have no photos from that second trip.  Maybe there will be a lucky third time?

The term 'Force' in the waterfall's name, by the way, comes from the Viking word for a waterfall. I was suitably impressed by it – this was the first decent-sized waterfall I had seen. It's no Angel Falls or Niagara but with its 20m drop it is spectacular by British standards and the geology, geomorphology and resulting landscape are quite something. 

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