Knightsford Bridge Quarry

Exposed Units: Aymestry Limestone Formation

At this disused quarry, the Amestry Limestone Formation has been overturned and the beds are highly fractured with some mineralisation in the joints.  The beds exposed in the quarry show a ~15m high section of calcareous siltstones and silty limestones.  The lowest part of the section comprises thinly bedded silty limestone and limey mudstones that contain abundant brachiopod shells. Above these, a ~8m succession of thinly bedded limestones contains increasing amounts of sandy material moving up through the sequence.  This is overlain by ~13m of limey silt that contains abundant examples of several species of brachiopod, as does the topmost layer of silt and fine-grained limestone. Although the sequence is similar in terms of rock type, the layers contain distinct assemblages of certain species of the brachiopod animal, which have been used to date the rock unit here to the mid-Silurian period of geological time.

Photos

Dipping beds of Aymestry Limestone at Knightsford Bridge Quarry.

Small scale faulting displacing calcareous shale beds in the Aymestry Limestone.

Dipping beds of Aymestry Limestone at Knightsford Bridge Quarry.

Brachiopod shell.

References

Barclay, W.J., Ambrose, K., Chadwick, R.A., and Pharaoh, T.C., 1997, ‘Geology of the country around Worcester’, Memoirs of the British Geological Survey, British Geological Survey, London.

March 2011