Stackpole Quay, Pembrokeshire

As well as being a very picturesque spot, Stackpole Quay is really interesting in terms of structural geology. The rocks are Carboniferous Limestone which have been folded and faulted. Of particular interest is the Stackpole Fault, which is a tear fault or strike-slip fault. This means that rocks on either side of the fault are shifted mainly horizontally relative to each other, rather than vertically. Here, the off-set across the fault is about 100 metres to the right (dextral). In some ways the Stackpole Fault is like a miniature version of California's San Andreas Fault, although the mechanism driving the fracture is different.

In this southwards view, the Stackpole Fault can be seen in the quarry face in the distance. It runs towards the camera, causing the outcrop of rocks in the harbour just to the right of the boat to be truncated suddenly. The camera location (i.e. me) is directly on the fault.

The main Stackpole Quay anticline axis is located in the slipway in the foreground on the RH side of the fault, but is truncated by the fault and off-set 100 m southwards to reappear at the far end of the harbour wall on the LH side of the fault.

Hmm... it takes a lot of words to explain. It's much easier to understand when you go there and see it for yourself :-)