In 2010 (I believe) we did a short trip to Cornwall. We visited Tintagel Castle, which I loved, and on the way back to the carpark, I noticed the presence of a remarkable rock within the drywall that runs parallel to the footpath communicating with the castle. There it was this fantastic example of buckle folding that deforms a nicely layered schist.
Simply put, buckling occurs when a rock folds by the effect of a compressional forces acting parallel to its layers, and typically in layered rocks where there is some contrast of competency amongst the beds. The other major folding mechanism is bending, which occurs by other causes, like oblique forces to bedding.
The rock shows a great cross-section of the buckles. You can also see reverse faulting, detachments and disharmornic folding… I like to show this photo as an example of fold-related folds, in opposition to fault-related folding: the reverse faults develop when the buckle has locked and cannot fold more, causing the brittle structure do form.
We were in Tintagel last October, and even though I looked carefully for the rock, I couldn’t find it.
Until next #FridayFold!