Tuesday, July 30, 2013

Glacial erratics and Samson's Toe

click photo to enlarge
One of the pleasures of growing up in the Yorkshire Dales was that school geography lessons sometimes referred to physical features that you already knew or that you could easily visit. The cliffs, gorges, tarn, sink holes, lead mines, clints and grykes etc of the area around Malham were cited as archetypes in the text books we used. So to be able to walk to the area from my home and examine these at first hand was a wonderful thing. The interesting rock strata of the Yoredale Series was clearly visible in the sharp, stepped profiles of Penyghent and Ingleborough, both ever-present on the horizon. The nearby classic fault line marked by the cliff along the edge of Giggleswick Scar was equally famous. And the much photographed Norber boulder field, with its glacial erratics of dark gritstone perched on the light grey native limestone, was but an energetic walk or an easy cycle ride away. It was through my exposure to the latter that I came to recognise other, less prominent, erratics scattered around the limestone hills where I lived.

The examples I was most familiar with were scattered across the area known as Attermire. These dark coloured lumps of rock were like ugly ducklings against the white of the Carboniferous limestone. Moreover, even though I knew that great sheets of ice, tens or hundreds of feet thick had transported them from places where they were the native rock and then, as the ice melted, deposited them on top of the entirely different rock of the Craven area of Yorkshire, it was still difficult to imagine such a process in action.

I recently photographed a glacial erratic that I never saw when I lived in the Dales. That's not because it was too distant from my home: in fact it's quite near. The fact is I'd never before walked the footpath that takes you past it. I learned that it had a name too. It's called "Samson's Toe" for reasons that are, I think, fairly obvious. I'm only aware of one other erratic (at least it's usually described as one) that has a name and that is the Great Stone of Fourstones near High Bentham. This enormous lump of rock with steps cut into it is better known to historians than geographers because it has long served as a boundary marker.

photograph and text © Tony Boughen

Camera: Sony RX100
Mode: Aperture Priority
Focal Length: 21.1mm (57mm - 35mm equiv.)
F No: f5.6
Shutter Speed: 1/320
ISO: 125
Exposure Compensation:  -0.3 EV
Image Stabilisation: On