Broadway Quarry

Exposed Units: Salperton Limestone, Aston Limestone, Birdlip Limestone

Conservation Status: Local Geological Site

Broadway Quarry is located within the Cotswolds Area of Outstanding Natural Beauty and lies adjacent to the Cotswold Way, one of the National Trail walking routes. The Quarry has been in operation for some 120 years and has extracted limestone for both aggregate and building stone. It provides an excellent natural environment resource and for these reasons the site is designated as both a Local Geological Site (LGS) and Special Wildlife Site (SWS).

Broadway Quarry has exploited Jurassic limestones from the Birdlip, Aston and Salperton Limestone Formations of the Inferior Oolite Group. The existing quarry can be divided roughly in half by a fault that runs WNW-ESE across the site. Rocks on the south side of the fault are displaced downwards by 22m to 25m and the Aston Limestone is folded into a small syncline in the east face of the Quarry. The fold and fault run parallel to each other, leading to the suggestion that the fold formed as a result of flexure in the crust at the time of fault movement.

The lower part of the Notgrove Member (of the Aston Limestone Formation) is seen at the top of the face at the back of the quarry, and overlies the full thicknesses of the Gryphite Grit Member. The Aston Limestone Formation and the Harford, Scottsquar and Cleeve Cloud Members of the Birdlip Limestone Formation are also exposed south of the fault that bisects the quarry. On the north side of the fault, only the Cleeve Cloud Member is seen, the Clypeus Grit Member of the Salperton Limestone Formation and the Notgrove and Gryphite Grit Members are exposed in a wedge of land where the fault splits into two arms.

The units in the quarry are present as a series of fossiliferous ooidal limestone with occasional interbeds of sandstone and shale. Of notable mention is the Harford Member, as Broadway Quarry exposes one of the beset sections of the unit. Here, the Harford Member comprises a ~8m section of sandstones and limestones, topped by a series of mudstones. The top unit is some 3.3m thick and contains large black masses of lignite, giving it a distinctive dark grey colour. As a consequence it stands out visually from the light coloured limestones and sandstones around it. The nature of the Harford Member indicates a change in environment at the time of deposition. In contrast to the shallow marine limestone of the other units, the presence of lignite indicates more terrestrial conditions and an environment restricted in oxygen – possibly a freshwater lagoon. The sands lying directly below the mudstone are unconsolidated, suggesting a deposition on a beach or nearshore environment.

Terminology

Fossiliferous – fossil-bearing

Ooidal limestone – a limestone that is made up of small, pellets of limestone called ooids. Ooids are formed in clear, shallow marine shoals when a small nucleus is rolled around by waves and currents in carbonate-rich sea water. They increase in size by ‘snowballing’ and are not formed by biological activity.

Lignite – also known as ‘brown coal’. This is a type of immature coal formed from the remains of plant matter deposited in a coastal/deltaic/swampy environment.

Photos

General view of Boradway Quarry, showing cream-coloured Jurassic oolitic limestone and the dark-grey Harford Member.

Folded structures in limestone beds have been exposed by quarrying.

General view of the quarry floor with piles of aggregate in the fore- and mid-ground.

Exposed face showing well-bedded limestone and shales. The Harford member is particularly well-defined.

Rock being crushed for aggregate.

References

Understanding the Historic Environment of Aggregate Landscapes, 2007, Extract from ALSF Annual Report, pp.3.

Barron, A.J.M., 1999, Report on Broadway Quarry, Worcestershire, British Geological Survey, Keyworth.

Barron, A.J.M., 2000, ‘Broadway Quarry, Worcestershire: An enlarged section in the Inferior Oolite Group’, Proceedings of the Cotteswold Naturalists Field Club, pp.309-321.

Broadway Quarry Wooded Spur application, 1996, D.K. Symes Associates, Technical report.

Jones, V.E., 1991, The County of Hereford and Worcester draft minerals local plan, Herefordshire & Worcestershire County Council, Worcestershire, pp. 59.

March 2011