Rhossili rock strata

The cliffs on the southern boundary of Rhossili Bay rise 60 metres above the sandy beach. They are composed of limestone laid down 290 to about 360 million years ago in the Carboniferous Period. The rocks of this period take various forms depending on the environmental conditions prevailing during their deposition. Carboniferous limestone is the oldest and lowermost type of rock in this geological sequence and is approximately 800 metres thick, with Millstone Grit and Coal Measures above it.

There are many different types of Carboniferous limestone with different textures, layer depth, and fossil groups. They include marine shales, muddy limestones, oolites (with minute rounded grainy texture), breccias (with angular fragments cemented together), and – as in these South Gower cliffs – the main limestone.

Originally the layers or strata of the limestone would have built up in horizontal beds, one on top of the other. However, over time, earth movements have crumpled the strata so that they are now tightly folded and pleated. The photographs of Carboniferous rock strata in this post show ‘pitching’ folds in which the axes of the folds are tilted at an angle. (The pictures have been taken with the camera held in a normal horizontal position).

If these folds could be straightened out, the width of the Gower Peninsula would be almost doubled!

E. M. Bridges in Classic Landforms of the Gower Coast