For today’s post I’ve gone for somewhere a little closer to home, and I reckon this is probably not far off how it looks now -it’s that cold. I’ve got to work up there next week, so here’s hoping for a thaw! The river Caerfanell in the Talybont valley is a real beauty spot, popular with tourists in the summer, and outdoor centres for the rest of the year. What draws the visitors are the waterfalls, which occur throughout the river’s upper course, and are ultimately the result of geology. A real gorgewalking playground, the river’s generally pretty shallow, but with enough water to get you wet! It’s also a great river for fieldwork, being so compact and accessible. I love it in the winter, when few are brave enough to venture out, and the airborne moisture turns into icicles on any available surface.
The bedrock here is part of the Old Red Sandstone, a sedimentary rock formed approximately 391 to 417 million years ago in the Devonian Period. To be specific, the rocks here are called Brownstones, and the reason they help the waterfalls form, as any good geographer knows, is to do with differences in the strength of the layers within this rock. The Brownstones are alternating bands of hard sandstones and softer fine-grained rocks -you can break the softer stuff just by hand- that formed on a floodplain beside an ancient river channel. All of this happened when Britain was part of a larger continent, somewhere around the Tropic of Capricorn: changing water levels and corresponding changes in kinetic energy because of a period of mountain building in the north led to sorting in the alluvial sediments, and the all-important layering. Move forward in time a few million years and the ‘modern’ streams start eroding away the rocks with a strong vertical component that eats straight down into the the soft rock, creating a step, and a waterfall is born. The result is a waterfall for nearly every soft layer/layers, and that means a photographers paradise, extending from the valley floor to near the top of the surrounding bluffs!
If you’re planning to buy a print, try 6″x4″ or scale it up.
All images ©Stephen Tyrrell; Mountains, Wild Places & Water, 2013. All rights reserved.