Selwicks Bay

Selwicks Bay

Dipping back in my A-level field notebook and in those pre-digital days, I found that colour prints could be more useful than slides, as I could stick them in my notebook. Here I’ve indicated a fault in the wave-cut platform of Selwicks Bay, Flamborough Head.

Flints in Chalk

flints
Flints in chalk

Flints are exposed in the chalk of the wave-cut platform south of the fault. Flints like these may have formed when the silica-rich skeletons of sponges and other creatures formed a gel on the seafloor which was drawn down into burrows in the chalk ooze – hence the shape of the nodules.

Buttress of Contorted Chalk

RockWATCH group guided around the features of the bay by geologist Richard Myerscough.

We looked at a buttress of contorted chalk south of the fault. The chalk contorted by the fault has been re-cemented by calcite-rich fluids circulating through the rock and depositing veins of calcite.

Strengthened by this cement the chalk is harder than that surrounding it and it has withstood erosion and formed a buttress.

Contorted Chalk with Calcite Veins

calcite vein

This vein is exposed on the wave-cut platform in front of the buttress.

Tilted layers near at the fault plane
Fault breccia: chalk crushed by movement along the fault
Fault and crush zone, Selwicks Bay, Flamborough Head