Swallowtree Bay anticline-syncline couplet

Saundersfoot to Swallowtree Bay geological structures

Just south of Swallowtree Bay near Saundersfoot, Lower Coal Measures sandstones and siltstones have been folded into an asymmetric anticline-syncline couplet. The folds display a variety of accommodation structures: minor thrusts disrupting the fold axes (particularly the antincline axis); minor thrusts causing crumpling and repetition of some bedding in the fold limbs; thinning of the fold limbs and thickenning in the fold axis. The sandstones display cross-bedding and erosive channel bases.

Scale: the height of the exposed rock section is about 6 metres in the vertically bedded zone.

Details of the fold couplet are shown in the photos which follow, indicted by the notes.