• Local GAPs

Slide Show

Gullet Pass Pit

Exposed units: Malverns Quartzite

Conservation Status: Local Geological Site; SSSI

This site is a classic locality, of national and international importance, providing one of the few good accessible exposures of basal Cambrian strata in the Malverns.  It is one of only a handful in England that provides an insight into early Cambrian sedimentary environments and global palaeogeography 540 million years ago.

This small old quarry is about 15m long, 3m wide and up to 4m high and contains a good exposure of the Malvern Quartzite.  At this locality the unit is a tough, grey quartz-rich sandstone and conglomerate. The toughness of the rock is due to its silica cement.  Vein quartz pebbles are the largest clasts (one elliptical pebble 350mm long was noted), and the smallest (2-3mm) are angular pinkish/red felsic clasts derived from the Malverns Complex.

The site also has palaeontological importance, having yielded five species of inarticulate, horny brachiopod and one hyolithid species. This fauna is comparable to that of the Comley Sandstone of Shropshire and provides a date for the onset of Cambrian sedimentation in the Malverns area. The beds are interpreted as the deposits of shallow-water shoreface and beach sands.  They record an important trangressive event, when the Lower Cambrian sea flooded the landmass of the Precambrian Malverns Complex, eroding it and producing the sediment which was laid down as the Malvern Quartzite.

A small north-south trending fault is present in the centre of the pit with the north-south face probably lying in its hanging wall.  The locality lies in a small triangular, fault-bounded outcrop of the Malvern Quartzite in Gullet Pass.

Terminology

Hyolithid – An extinct species of invertebrate from the Cambrian Period.

Hanging wall – The block of crust that lies above a fault (opp. foot wall).

Felsic – Containing the mineral feldspar.

Photos

Exposure of Malvern Quartzite at Gullet Pass Pit.

References

Groom, T.T., 1899, The Geological structures of the southern Malvern Hills and the adjacent district to the west, Journal of the Geological Society, vol. 55, pp. 139-140.

Groom, T.T. 1902, The sequence of the Cambrian and associated beds of the Malvern Hills, Journal of the Geological Society, vol. 58, pp. 89-135.

Horner, L., 1811, On the mineralogy of the Malvern Hills, Transactions of the Geological Society of London, vol. 1, pp. 302.

Rushton, A.W.A., Owen, A.W., Owens, R.M. & Prigmore, J.K., 2000, British Cambrian to Ordovician Stratigraphy, Geological Conservation Review Series, vol. 18, pp. 436.

Click here to request data