This description is adapted from a report written by W.J. Barclay in 2009.
This small former quarry is a classic locality, providing one of the few good exposures of basal Cambrian strata in the Malverns and is designated as a Site of Special Scientific Interest (SSSI). It is a site of national importance.
The locality lies in a small triangular, fault-bounded outcrop of the Malvern Quartzite in Gullet Pass. Close below, exposures on the Gullet Pass Path, after a period of heavy rain, used to show the junction between the Cambrian Malvern Quartzite and the Precambrian (Neoproterozoic) Malverns Complex. The exposures in the path, now covered in mud, appeared to show an unconformity in which tough, very jointed, dark grey, pebbly, coarse-grained quartzite with conglomerate lenses overlies an irregular surface of pink felsite of the Malverns Complex. The quartzite crops out for 15m and is much tectonised, with variable dips and some near-vertical minor folding. The basal bed of the Malvern Quartzite appears to drape an irregular surface of Malverns Complex and contains rounded quartz pebbles and angular clasts of pink feldspar and felsite. Immediately to the east, green (pink-mottled) jointed diorite of the Malverns Complex is exposed in the track for 20m. Further research is required at this locality to fully understand the relationship between the two rock units.
The quarry was re-excavated by the Herefordshire and Worcestershire Earth Heritage Trust in 2002 and cleared again in 2015. The rock comprises tough, (because of its silica cement) grey conglomeratic quartzitic sandstone and grey conglomerate. The conglomerates are unsorted and framework-supported and the clasts range from mm-size up to 350mm, with an average size of 2 to 3mm. They range from angular to rounded, with most being angular/subangular/subrounded. Vein quartz pebbles are the largest clasts (one elliptical pebble 350mm long was noted), and the smallest (2-3mm) are angular pinkish/red felsic Malverns Complex clasts. Large, angular clasts of Malverns Complex are present in the lowermost beds.
The dip of the strata ranges between 30o and 40 o to the north-north-west, dipping towards the fault which runs up the Gullet Pass. A bedding plane in the centre of the quarry has trace fossils on its surface. There are sets of joint planes dipping to the east.
The site 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 of 543 to 511 million years ago for the onset of Cambrian sedimentation in the Malverns area. The fossils recorded from the pit belong to a low-diversity, shallow-water suite and include the horny brachiopods Paterina phillipsii, Obelella? Groomi and rare hyolithids (conical shelled, mollusc-type animals) including ‘Hyolithes (sensu lato) primaevus.
The beds are interpreted as the deposits of shallow-water shoreface and beach sands, because of the clean nature of the quartzites, their planar cross-bedding, the pebble lenses and the contained fossils, which were reworked and broken by currents. The beds record an important trangressive event, when the Lower Cambrian sea flooded the landmass of the Precambrian Malverns Complex. Erosion of the landmass produced the sediment which was laid down as the Malvern Quartzite. The area lay on the margin of the Welsh Basin, in which a great thickness of mud was deposited; the area was then part of the Midlands Microcraton. On a larger scale, the area lay on the microcontinent of Eastern Avalonia, and the fossils at Gullet Pass provide, along with other scattered outcrops of Cambrian strata in England, an important correlation with similar rocks in Newfoundland.
BRENCHLEY, P.J., RUSHTON, A.W.A., HOWELLS, M. and CAVE, R. 2006. Cambrian and Ordovician: the early Palaeozoic tectonostratigraphic evolution of the Welsh Basin, Midland and Monian terranes of Eastern Avalonia. Pp. 25-74 in BRENCHLEY, P.J. AND RAWSON, P.F. (editors). The Geology of England and Wales. Geological Society of London.
COWIE, J.W. and SPEEDYMAN, D.L. 1977. The southern Malvern Hills'. pp. 3-15 in SAVAGE, R.J.G. (Editor) Geological excursions in the Bristol district. (Bristol: Univ Bristol).
GROOM, T.T. 1899. The geological structures of the southern Malvern Hills and the adjacent district to the west. Quarterly Journal of the Geological Society of London, Vol. 55, 139-140.
GROOM, T.T. 1902. The sequence of the Cambrian and associated beds of the Malvern Hills. Quarterly Journal of the Geological Society of London, Vol. 58, 89-135.
HORNER, L. 1911. On the mineralogy of the Malvern Hills. Transactions of the Geological Society of London, Vol. 1.
HUMPHREYS, A.P. 1956. The fauna of the Malvern Quartzite. Private publication.
MOORLOCK, B.S.P. 1979. 1:10560 geological sheet SO73NE. British Geological Survey.
SWEETING, G.S. 1927. The petrography of the Malvern Quartzite, Hollybush Sandstone and May Hill sandstone exposed in the Eastnor (Herefordshire) district. Proceedings of the Geologists’ Association, Vol. 38, 548-60.
RUSHTON, A.W.A., OWEN, A.W., OWENS, R.M. and PRIGMORE, J.K. 1999. British Cambrian to Ordovician Stratigraphy. Geological Conservation Review Series No. 18. Joint Nature Conservation Committee. Peterborough.
WORSSAM, B. C., ELLISON, R.A. and MOORLOCK, B.S.P. 1989. Geology of the country around Tewkesbury. Memoir of the British Geological Survey, Sheet 216 (England and Wales).