• Local GAPs

Slide Show

Bartestree Quarry

Exposed units: Bartestree Dolerite, Raglan Mudstone

The Bartestree Dolerite is an intrusion of dolerite into the Silurian Raglan Mudstone Formation along the line of the Neath Disturbance, measuring 13.5m wide where it crops out at the WSW end of the quarry. It is a composite intrusion, having been formed by the sequential injection of three phases of basic material:

First phase

Green dolerite without olivine is seen on the southern extent of the outcrop.

Second Phase

Composed of teschenite, a type of dolerite characterised by the mineral assemblage olivine-analcime (zeolite).  This solidified before the intrusion of phase three.

Third phase

Basalt forms the central and major part of the dyke.

The dyke intrudes into the silty mudstones of the Raglan Mudstone Formation, which have undergone contact metamorphism close to the dyke margins, suggesting that the dolerite was intruded into cold country rocks.

Early workers suggested that the dyke may have been related to the latest stages of the Variscan Orogeny and suggested an age of ca. 295 million years as the age of emplacement and consolidation. The dyke has since been dated to between 260+/-20 million years and 186+/-18 million years and has been correlated with other Carboniferous-age dolerite in the Midlands.

There are no images available for this site.

Terminology

Teschenite – A mafic (iron-magnesium rich) igneous rock that cooled underground.

Dyke – A body of igneous rock that has been intruded into the surrounding rocks and has a ‘sheeted’ geometry. This ‘sheet’, cuts across the sedimentary layering in the surrounding rocks.

Variscan Orogeny – A period of mountain building in central Europe, North America and southern England that took place between 380 and 280 million years ago.

References

Fitch, F.J. and Miller, J.A., 1964, ‘The age of the paroxysmal Variscan Orogeny in England’, in W.B. Harland, A. Gilbert Smith, B. Wilcock (eds.) The Phanerozoic Time-Scale: A Symposium, Geological Society Special Publications, London, pp. 159-175.

Fitch, F.J. and Williams, S.C., 1970, ‘Isotopic ages of Carboniferous rocks’, Conference Report of the 6th Congress on International Stratigraphic Geology, pp. 771-789.

Reynolds, S.H. 1908, ‘The basic intrusion of Bartestree, near Hereford’, Quarterly Journal of the Geological Society, vol. 64, 4, pp. 501-511.

Click here to request data

Beech Cottage Quarry

Exposed Units: Avon Group

This disused quarry is a private site, part of the owner’s garden.

The quarry exposes thinly bedded sandstones, and shales overlain by more massive limestones.  Some beds show ripple marks, current-bedding and desiccation cracks showing that the sediment was laid down where the water was shallow or dried out completely.  Fossils of brachiopods and crinoids have been found.

No references are available for this site.

Photos

General view of the exposure at Beech Cottage Quarry.

Current bedding in sandstones at Beech Cottage Quarry.

 

 

 

 

 

 

 

 

Click here to request data

Bircher Common – Welshman’s Lane

Exposed Units: Upper Ludlow Shales Group

The majority of this circular-shaped quarry is overgrown by trees and scrub leaving only one face exposed. The quarry exposes the Whitcliffe Beds, which form the upper part of the Upper Ludlow Shales Group.

The outcrop is heavily jointed and has a sandy brown weathered surface.  In fresh section, the rock is a laminated micaceous (mica-bearing) siltstone with shaley intervals (approximately 2-3 centimetres in thickness).  There is variation in hardness and colour (light buff to light brown) throughout the outcrop.  The unit contains abundant brachiopod fossils up to 8mm in length, which are seen cross-cutting laminations and weathering out along jointing planes.

Weathered out casts are common features along the jointed quarry face and appear to be weathered out nodules of up to 30 centimetres in diameter.  As seen at the Leinthall Earls Road site, the casts appear associated with certain horizons.  Similar features were found elsewhere in the quarry in filled with muds.  Convolute bedding and cross bedding are common.

There are no key references for this site.

Photos

General view of quarry showing the faces largely overgrown by gorse.

Nodules in the Whitcliffe Member that have preferentially weathered out, leaving hollows up to 30cm in diameter.

Convoluted bedding in the Whticliffe Member formed during sedimentation, when wet sediment slumped down the slope on which it was deposited.

Cross bedding in the Whitcliffe Member, indicating sediment deposition in flowing water.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Click here to request data

Blackbush Farm

Exposed units: Bishop’s Frome Limestone, Raglan Mudstone

This L-shaped quarry gives the best exposures of the Bishop’s Frome Limestone in the area. The quarry exposes a good section of the mature calcrete that characterises the unit.

The Bishop’s Frome Limestone here comprises blue-red nodular limestones with pale red and cream-coloured solution channels. The unit has ahigh clay content in the bottom 2.5m of the unit but grades into a more pure limestone towards the top.   The silage clamp on the west side of the quarry contains a fault plane with well-developed slickensides, suggestive of fault activity with downwards movement to east, although the extent of displacement is unknown. One part of the quarry exposes a small Quaternary U-shaped drainage channel that is seen to cut down into the Bishop’s Frome Limestone.

There are no key references for this site.

Terminology

Slickensides – A smoothly polished surface caused by frictional movement between rocks along a fault plane.

Photos

Red-coloured, blocky calcrete of the Bishop’s From Limestone. The red staining is due to the presence of oxidised iron in the rock, indicating the unit’s formation in an arid, well-oxygenated environment.

Click here to request data

Brockhill Farm Quarry

Exposed units: Upper Ludlow Shales

The quarry faces extend over 60m from east to west and expose an almost continuous section across the Silurian Ludlow – Pridoli boundary.  In the eastern part of the quarry, the uppermost beds of the Upper Ludlow Shales are exposed.  These beds, also known as the Whitcliffe Beds, are predominantly calcareous siltstones with occasional limestone horizons.  They are fossiliferous.  At the very top, the siltstones give way to 6m of thinly bedded, micaceous, current rippled sandstones with shale partings.  About three quarters of the way along the face, the transition from marine to non-marine sedimentation is shown by a change from the siltstone with marine fossils to the river sediments of the Downton Castle Formation.

In the western part of the quarry, a small section through the Downton Castle Sandstone is exposed, overlying the weathered surface of the Upper Ludlow Shales.  The rocks are fine-grained, buff coloured and comprise quartz, muscovite and limonite.  They are thought to have been deposited in a fluviatile environment.

The Whitcliffe Beds here contain an abundant fauna including brachiopods Protochonetes and Camarotoechia as well as mollusca.  The Downtonian contains only the brachiopod Lingula which may occur in the sandstone bands and occasional plant material.

 

Photos

Dr Paul Olver, a geologist on the Trust’s Executive Committee explains the geology on a field trip to Brockhill Farm Quarry.

 

References

Barclay, W.J., Ambrose, K., Chadwick, R.A. and Pharaoh, T.C., (1997), Geology of the country around Worcester, Memoir of the British Geological Survey Sheet 199, 156pps.

Penn, J.S.W. and French, J., (1971), The Malvern Hills, Geologists’ Association Guides; Geologists’ Association.

Click here to request data

Coneygree Wood Quarry

Exposed Units: Much Wenlock Limestone, Elton Formation (Lower Ludlow Shales)

Conservation Status: Local Geological Site

The right hand side of the quarry exposes rock dipping at an angle of about 45°. The rock units at this locality are grey-green limestones that are slightly nodular at the base of the outcrop. Above this zone of nodular limestone, the beds are thinly layered (20cm width) and are made of a fine grained material which is possibly bentonitic in origin. This small face contains beds with abundant brachiopod fossils, a species of bivalve that may be related to the pectinoid family.

Structural geology is more important than lithology at this site; a well-defined fold hinge and limb are apparent across ~20m of exposure. The core of the fold could lie at the base of the exposure. There is also a regular series of radiating fractures related to the fold axis (that would correspond to coeval cleavage plane development). The structures preserved at this locality are important in understanding the 3D geometry of rocks in the surrounding area, as the site forms part of a larger fold structure called the Ledbury Anticlinorium.

Terminology

Slickenside - a smoothly polished surface caused by frictional movement between rocks along the two sides of a fault, which is normally striated in the direction of movement.

 

Photos

References

Wilson, J., 1990, The limestone quarries and kilns of Ledbury, pp.7pp

Basset, M.G., 1970, ‘The articulate brachiopods from the Wenlock series of the Welsh borderland and south Wales, Part 1’, Monograph of the Palaeontological Society, vol. 123, no. 525, pp.26.

Click here to request data

Croft Castle Quarries

Exposed Units: Aymestry Limestone

Conservation Status: Site of Special Scientific Interest (and others)

The quarries found on the Croft Castle Estate sit within Fishpool Valley. Both of the quarries display fine examples of the Aymestry Limestone Formation. The quarries are large, with the northern quarry being long and narrow at 40m long and 8m deep, with 3-4m high rock faces. The southern quarry is 30m wide, 40m deep and has rock face that reaches 5-6m.

Both quarries display bedded nodular clay-rich limestones and calcareous (calcium carbonate rich) siltstones that are typical of Aymestry Limestone Formation exposures. The nodules are more pronounced in the northern quarry, where weathering has eroded away much of the lime cement, which allows for the shapes of the nodules to be seen more clearly. Both quarries also contain thin layers (4-6cm thick) of calcareous siltstones. These thin siltstones are separated by approximately 2m of the nodular limestones. Due to their soft compositions they have weathered preferentially in comparison to the harder limestones and therefore can be easily identified.

The beds in the northern quarry are dipping (tilting) approximately 6˚ to the south-east. This dip is attributed to the fact that the rocks in this area are sitting on the southern limb of large anticlinal fold. This structure is known as the Ludlow Anticline, formed during a period of mountain building in the mid-Devonian Period (391Ma).

This site is part of the Community Earth Heritage Champions Project.

Terminology

Fold – A curved or angular shape of an originally planer geological structure.

Anticlinal fold – A fold closing in any direction in which the older rocks occupy the core.

Photos

Nodular limestone beds in the Aymestry Limestone at Croft Castle Quarry 1.

Back wall of Aymestry Limestone at Croft Castle Quarry 2.

Nodular limestone beds in the Aymestry Limestone at Croft Castle Quarry 2.

Community coral fossils at Croft Castle Quarry 1.

Solitary coral fossils as Croft Castle Quarry 1.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

References

Aldridge, R et al. 2000. British Silurian Stratigraphy. Geological Conservation Review Series Volume 19. Joint Nature Conservation Committee.

Brenchley, P.J. and Rawson, P.F. 2006. The Geology of England and Wales. The Geological Society. The Geological Society Publishing House, Bath.

British Geological Society. 2000. Ludlow, England and Wales Series Sheet 181 (Provisional Series). Solid and Drift.

Cross, P. 1966. The Glacial Geomorphology of the Wigmore and Presteigne basins and some adjacent areas. Thesis, MSc, Univ London. 89pp.

Holland, C.H. & Lawson, J.D. 1963. Facies patterns in the Ludlovian of Wales and the Welsh Borderland. Liverpool Manchester Geological Journal, 3 (2), pp269-288.

Lawson, J.D. & Straw, S.H. 1956. The Ludlovian rocks of the Welsh Borderland. Advanced Science. 12 pp563-570.

Lawson, J.D. 1960. The succession of shelly faunas in the British Ludlovian. Report on the International Geological Congress, Norden (XXI session), (7), pp114-125.

Lawson, J.D. 1973. Facies and faunal changes in the Ludlovian rocks of Aymestrey, Herefordshire. Geology Journal. 8 (2), pp247-278.

Lawson, J.D. 1999. Watkins’ benthic associations in the Ludlow series of the Welsh Borderland. in BOUCOT, AI and LAWSON, JD (EDS), Palaeocommunities: a case study from the Silurian and lower Devonian. Cambridge: Cambridge Univ Press; World and regional geology series. 11 (29), pp388-394.

Newell, G. 1966. A faunal and sedimentary study of the Aymestry Limestone and adjacent beds in parts of Herefordshire and Shropshire. Ph.D thesis, Univ. Manchester.

Siveter, D.J. et al. 1989. The Ludlow anticline and contiguous areas: a shelf marine to non-marine transition. in Siveter, D.J, Owens, R.M. and Thomas, A.T., Silurian field excursions: a geotraverse across Wales and the Welsh Borderland. National Museum of Wales, Geological Ser. 10, pp37-70.

Watkins, R. 1979. Benthic community organization in the Ludlow Series of the Welsh Borderland. Bulletin British Museum Natural History (Geology). 31, pp175–280.

Woodcock, N. and Strachan, R. 2000. Geological History of Britain and Ireland. Blackwell Scientific Publications.

Click here to request data

Fowlet Farm Quarry

Exposed units: Ordovician Intrusive suite

The site is a disused quarry in a volcanic boss on the top of a promontory of high ground.  The quarry is about 24 x 15m in size and 2.5m deep.  It offers one of the best and most extensive exposures of the Ordovician igneous intrusions into the local silver-grey shales of the early Ordovician Bronsil Shale Formation.

About half of the circumference of the quarry shows an exposure of the intrusive rock, which is red coloured on the weathered faces.  The rock appears fairly uniform in nature but the three samples taken show a large variation.  There is a great deal of rubble remaining from which good samples can be obtained of strong but weathered rock. No contact with the surrounding shales is exposed.

At Fowlet Farm Quarry, the intrusion is described by geologists as a spilitic andesite with a porphyritic texture. It is set in a microcrystalline groundmass of zoned oligoclase or albite, together with minor amounts of the minerals chlorite, apatite, magnetite, ilmenite and pyrite. Andesite is a rock consisting of the mineral oligoclase (a sodium-bearing plagioclase feldspar) with one or more mafic (iron-magnesium rich) minerals.  The presence of ‘spilite’ suggests the andesite has been chemically altered by a reaction with sea water or hot fluids. The term ‘porphyritic’ refers to the presence of crystals that are visible to the naked eye and these are set in a background (or groundmass) of microscopic crystals of plagioclase feldspar, chlorite and other minerals present in trace amounts.

Photos

General view of Fowlet Farm Quarry.

View of main quarry face with scree slope.

View of partly overgrown quarry face.

 

 

 

 

 

 

 

References

Blyth, F.G.H., 1935, ‘The basic igneous intrusions of the Cambrian Inlier near Malvern’, Quarterly Journal of the Geological Society, vol. 91, pp. 463-478.

Groom, T.T., 1901, ‘On the igneous rocks associated with the Cambrian bed of the Malvern Hills’, Quarterly Journal of the Geological Society, vol. 55, pp. 139-140.

Hardie, W.G., 1969, ‘A Guide to the Geology of the Malvern Hills and Adjacent areas’, Worcetershire Education Committee, pp. 54.

Click here to request data

Frith Barn Quarry

Exposed units: Upper Ludlow Shales

This disused quarry exposes about 3m of khaki-coloured, quite thickly bedded siltstones with abundant brachiopod and bivalve fossils towards the top of the Upper Ludlow Shale Formation. On average the beds dip 30 – 45o down towards the northwest but are overturned in the south-west corner of the quarry. This overturning is most likely due to folding associated with faulting; however previous work attributed the overturning to soil creep. Bedding in the middle of the quarry is also disturbed and variable, and the strata broken and cambered.

Access to the higher exposures is generally quite difficult, due to vegetation-covered scree slopes. However, easily accessible exposures are present in the northern corner of the quarry. The beds are extremely fossiliferous, and also contain a range of brachiopod and bivalve species.

Terminology

Overturned – upside-down

Soil creep – gradual movement of soil down a slope due to gravity.

Photos

Well defined, tilted bedding in the Upper Ludlow Shales at Frith Barn Quarry.

Tilted bedding in the Upper Ludlow Shales at Frith Barn Quarry.

Fold hinge in the upper Ludlow Shales at Frith Barn Quarry. The rocks are folded so that beds on one side of the fold hinge are overturned.

Detail of bedding at Firth Barn Quarry, showing well-defined siltstone beds dipping down towards the left of the image.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

References

Moorlock, B.S.P., 1986, Geological notes and local details for 1:10,000 sheets SO73NW (Ledbury), Report of the British Geological Survey, London.

Click here to request data

Gardiners Quarry

Exposed Units: Malverns Complex

Conservation Status: Local Geological Site; SSSI; Within an AONB

Gardiners Quarry is one of many aggregates quarries that can be found across the Malvern Hills. Found on the western side of the hills, it is a small quarry; 30m across and 15m high. Currently the quarry is used as a Malvern Hills Conservators car park, as it one of the main points of access to the hills above.

The dominant rock type in Gardiners Quarry is diorite belonging to the Malverns Complex. A metadolerite dyke is located in the centre of the quarry.

Throughout the quarry there is also a series of pegmatite dykes. Made of a coarse granitic material, these pegmatites cut through the diorites that compose the majority of the exposure within the quarry. Muscovite, together with minor amounts of biotite, chlorite and epidote can be found as accessory minerals

In the south eastern part of the quarry there is a large granitic intrusion which has been sheared intensely. This zone of shearing is thought to be the continuation of the NW-SE trending Colwall Fault; a normal fault that runs through the village of Colwall, north-west of Gardiners Quarry.

Both the diorite and granite within the quarry have a sheared fabric. This shearing occurred during the first phase of metamorphism experienced by the rocks of the Malvern Hills. The intensity of shearing varies throughout the exposure. The shearing has also made rock boundaries and the relationships between rock units hard to determine.

From the quarry, the landscape of Herefordshire can be viewed, with the prominent ridges made of Silurian limestone running parallel to the Malvern Hills. Beyond these ridges the Woolhope Dome and Shucknall Inlier can be identified, with the flat Herefordshire plain in the distance. On days where the visibility is high, the Black Mountains of the Welsh Borderlands can be seen.

This site is part of the Community Earth Heritage Champions Project.

Terminology

Sheared – Where a rock is subject to directional stress (i.e. pressure with a directional element), minerals in the rock to realign according to the direction in which the pressure is directed.

Normal Fault – Movement along a line of weakness in the Earth’s crust where the hanging wall (land on top of the fault) is displaced downwards relative to the footwall (land underneath the fault).

Inlier – An area of older rocks surrounded by younger rocks

Photos

General view of Gardiners Quarry.

Granitic intrusion in zone of intense shearing (facing East).

 

 

 

 

 

 

 

 

References

Barclay W.J. et al. (1997) Geology of the county around Worcester. British Geological Society Memoir. London.

British Geological Survey (1993) Geology of the country around Worcester. Sheet 199: 1:50,000

Bullard D.W. (1989) Malvern Hills; A student’s guide to the geology of the Malverns. Nature Conservancy Council. Peterborough.

Butcher N.E. (1962) The Tectonic Structure of the Malvern Hills. Proc. Geol. Soc. 73 pp.103-123.

Falcon N.L (1947) Major Clues in the Tectonic History of the Malverns.

Fitch F.J. (1966) Isotopic age determinations on rocks from Wales and the Welsh Borderland. pp. 22-45 in Pre-Cambrian and Lower Palaeozoic rocks of Wales. Wood, A (Editor). University of Wales Press.

Kellaway G.A. and Hancock P.L. (1983) Structure of the Bristol District, Forest of Dean and the Malvern Fault Zone. in The Variscan Fold Belt in the British Isles. Hancock P.L. (Editor). Adam Hilger LTD. Bristol.

Lambert R. St J. and Holland J.G. (1971) The Petrography and Chemistry of the Igneous Complex of the Malvern Hills, England. Proc. Geol. Ass. 82. pp. 323-352.

Penn J.S.W. and French J. (1971) No 4: The Malvern Hills. Geologists Association Guides.

Pharoah T.C. et al. (1987) Geochemical Evidence of the Tectonic Setting of Late Proterozoic Volcanic Suites in central England. Geol. Soc. Special Publication No. 33. pp. 541-552.

Pharoah T.C and Gibbons W. (1994) Chapter 10: Precambrian rocks in England and Wales south of the Menai Strait Fault System. from Gibbons W. and Harris A.L: A revised correlation of Precambrian rocks in the British Isles. Geol. Soc. Special Report No. 22.

Phipps C.B. and Reeve F.A.E. (1967) Stratigraphy and Geological History of Malvern, Abberley and Ledbury. Geological Journal. 5 (2).

Timins Rev J.H. (1867). On the Chemical Geology of the Malvern Hills. Proc. Geol. Soc.

Thorpe R.S. (1972) Possible subduction zone origin for two calc-alkaline plutonic complexes from Southern Britain. Bulletin of the Geological Society of America. 83 pp. 115-120.

Thorpe R.S. (1987) Psuedotachylite from a Precambrian shear zone in the Malvern Hills. Proc. Geol. Ass. 98 (3) pp. 205-210.

Tucker R.D. and Pharoah T.C. (1991) U-Pb zircon ages for Late Precambrian igneous rocks in Southern Britain. Journal of the Geological Society. 148 pp. 435-443.

Woodcock, N and Strachan, R. 2000.Geological History of Britain and Ireland. Blackwell Publishing.

Click here to request data

Great Corras Quarry

Exposed Units: St Maughans Formation

This small quarry exposes a thick intraformational conglomerate that is overlain by sandstones. The conglomerate layers contain quartz pebbles and rip-up clasts of mud and calcrete. There is planar cross bedding in both sandstones and conglomerate. The sandstone is mainly parallel laminated.  These have been interpreted as river channel deposits, which were thought to have been laid down rapidly, for example, during a flash flooding event.

There are no images available for this site.

Terminology

Conglomerate – A rock made up of coarse, rounded material, such as pebbles that is surrounded by a fin grained matrix, such as sand or mud.

Intraformational conglomerate – A conglomerate that contains material derived from the same rocks that make up the sedimentary basin that the conglomerate is deposited in.

Rip-up clasts – Pieces of theground surface or river bed that is ripped up and incorporated into a deposit during a period of rapid erosion, such as a flash flood event.

References

Anon, 1954, ‘Directory of British fossiliferous localities’ Palaeontological Society, pp. 268.

Click here to request data

Gullet Main Quarry

Exposed Units: Malverns Complex

Conservation Status: Local Geological Site

Much of the Precambrian sequence is exposed in the high vertical faces of the north side of Gullet Quarry. The Malverns complex is very varied at this locality with a variety of rock types exposed. The Malverns Complex country rock is dominated by highly deformed diorite. The diorite itself has been intruded by several generations of intrusive igneous rocks, including microdiorite dykes, quartz-feldspar pegmatite and pink granite veins.  Gneissic textures are particularly well developed at the western end of the site, where small scale folding of the foliation is visible. Mica schists are also present and have an inferred metasedimentary origin. The Malvernian rocks are also intruded by mineralised veins containing the minerals calcite, epidote and haematite, which occurs on most joint and fracture surfaces throughout the quarry.

The Malverns Complex at Gullet Main Quarry is intensely deformed. Almost every boundary between different rock types has been sheared. A prominent NE-trending foliation dips steeply to the south-east, and is gneissose in places. This gneissose fabric is accentuated by intrusions of thin pink granite veins parallel to the fabric. These have been broken up in places, forming boudinage structures. The intense shearing affects all lithologies in the Malverns Complex, including the late microdiorite dykes and so occurred after the Precambrian. It is likely that some deformation is related to the Variscan orogeny; however it is also possible that the area has been affected by even younger deformation associated with the East Malvern Fault.

The contact between the Malverns Complex and the Wyche Formation is seen in the upper part of Gullet Quarry and this is described in more detail in the entry for Gullet Top Quarry.

Terminology

Gneissic fabric – A deformation fabric seen in metamorphic rocks that is characterised by prominent mineral banding

Schist – A deformation fabric in metamorphic rocks characterised by alignment of platy minerals, such as micas.

Metasedimentary – Term used to describe a sedimentary rock that has undergone metamorphism

Mylonite – An extremely fine-grained rock that has undergone intense deformation. These usually occur within fault zones where the deformation is most intense.

Boudinage – A structure that is formed when a rock is sheared so intensely that it is pulled apart. The resulting pieces resemble a string of sausages.

Photos

View of the main face at Gullet Main Quarry.

Near vertical, pale granitic pegmatites in the Malverns Complex.

Malverns complex diorite showing a steeply-dipping gneissic fabric defined by thin, white bands of the minerals quartz and feldspar and pink veins of granite pegmatite.

 

 

 

 

 

 

 

 

 

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, London.

Bullard, D.W., (1989) Malvern Hills – ‘A student’s guide to the geology of the Malverns’ Nature Conservancy Council.

Carney, J.N., Horak, J.M., Pharaoh, T.C., Gibbons, W., Wilson, D., Barclay,W.J., Bevins, R.E., Cope, J.C.W. & Ford, T.D. (2000), ‘Precambrian Rocks of England and Wales’, Joint Nature Conservation Committee, Peterborough.

Click here to request data

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

Gullet Top Quarry

Exposed Units: Malverns Complex, Wyche Formation

Conservation Status: Local Geological Site; AONB

The nature of the contact between the Malverns Complex and the overlying Silurian rocks has been a matter of debate for many years, although the balance of opinion now favours an unconformable relationship. A fault which cuts the Silurian sequence and extends into the Malvernian below is probably of Upper Carboniferous age, associated with the uplift of the hills.

Gullet Quarry shows a section through the Wyche Formation of the early Silurian, directly overlying Precambrian Malverns Complex. A conglomerate at the base of the Silurian, resting on an undulating surface of Malverns Complex, contains a layer of shelly limestone embedded in which are pebbles and boulders of Malverns Complex granite, with coral and brachiopods in the position of growth.  A retreating cliff-line with seashore stacks is visualised as the environment at this time.

Above the conglomerate a series of sandstones, limestones and shales of the Wyche Formation yield abundant fossils at some levels, especially in the decalcified limestones, and include several species of brachiopod, corals and nautiloids (cephalopods). Two marine fossil communities have been described at this locality, which represent a gradual change in the marine environment from shallower to deeper water.  The unit also preserves good examples of Silurian microflora (acritarchs) and conodonts have also been recorded in the limestones. The rocks display good sedimentary structures, such as scours, groove casts and impact marks. Occasional layers of ripple drift bedding may also be found, indicating deposition in moving water.

The Malverns Complex at this site is a grey cataclasite. The rock is schistose and contains bands of the minerals quartz and feldspar, which are separated by thin laminae of the minerals muscovite and chlorite. It is these two minerals that give the rock a schistose texture.

Terminology

Cataclasite – A type of rock formed by fracturing during faulting. It is characterised by large, angular pieces of rock surrounded by finer-grained material.

Unconformity – A surface between two rock units that represents missing time. An unconformable surface, which is typically an erosive surface, indicates that the deposition of rock units on either side was not continuous.

Schist – A rock fabric formed by deformation that is planar in geometry and defined by platy (sheet-like) minerals, such as biotite, muscovite and chlorite.

Conodonts – Extinct groups of vertebrate animals.

 

Photos

Steeply dipping beds of the Wyche Formation at Gullet Top Quarry.

Generaly view of the boundary between well-bedded Wyche Formation (left) and grey Malverns Complex (right).

Detail of grey Malverns Complex cataclasite.

 

 

 

 

 

 

 

 

References

Bullard, D.W., 1989, Malvern Hills – A student’s guide to the geology of the Malverns, Nature Conservancy Council, Peterborough, pp.

Phipps, C.B., Reeve, F.A.E., 1964, ‘The Pre-Cambrian – Palaeozoic boundary of the Malverns’, Geological Magazine, vol. 101, pp. 397-408.

Ziegler, A.E., Cocks, L.R.M. & McKerrow, S., 1968, ‘The Llandovery transgression of the Welsh Borderland’, Palaeontology, vol. 11, pp. 736-782.

Click here to request data

Hackley Farm 1

Exposed Units: Hackley Limestone

Limestone was formerly quarried in three small pits and 4m of exposure was recorded by the British Geological Survey; however the sites are now marked by small depressions and no exposures. At the southernmost site badgers have excavated plenty of samples of the limestone. This chemical limestone (calcrete) is found within the Devonian St Maughans Formation.  The samples indicate a pedogenic limestone, which is green/blue in colour and mottled red.  Several processes are recorded within this fossil soil, including the development of fluid channels followed by evaporation.

There are no photographs available for this site.

Terminology

Pedogenic (sic pedogenesis) – The process by which a soil develops. In this context, the Hackley Limestone formed part of the soil.

References

Brandon, A., 1989, ‘Geology of the country between Hereford and Leominster’, Memoir of the Geological Survey of Great Britain, Sheet 198, pp. 62.

Click here to request data

Haffield House Quarry

Exposed Units: Clent Formation (Haffield Breccia)

This is the type section for the Clent Formation, known locally as the Haffield Breccia Formation, at the base of the Permo-Triassic succession. The breccia forms a marked unconformity on Silurian and Malvern Complex rocks and forms a pronounced ridge between The Vineyard and the Glynch Brook Valley.

At this site, the Formation comprises poorly sorted, hematite-coated, subangular clasts of Malverns Complex rocks (mainly sheared, pinkish brown granite and dark green diorite) and greenish grey and purple-brown May Hill Sandstone and siltstone set in a matrix of purple to dark red brown, sandy siltstone and mudstone.  The clasts are mostly less than 10cm across, but blocks up to 1m in diameter have been recorded.  The sediments are generally well bedded, some beds having erosive bases scouring down as much as 30cm into the underlying sediments.  In some of the southernmost exposures, the beds are less than 8 cm thick, many consisting of a thin basal breccia fining upwards into coarse-grained sandstone with only a few small clasts.

No flora or fauna has been recorded from the Haffield Breccia, but by comparison with the Clent Formation elsewhere in the West Midlands, a tentative age of Lower Permian is suggested.

Photos

Rock face at the Haffield House Quarry showing well beddd, pink-coloured sedimentary units of the Clent Formation (Haffield Breccia).

The breccias at Haffield House Quarry, showing angular blocks set in a pink matrix of finer-grained material.

A close-up of the breccia at Haffield House Quarry, showing a large range in clast size.

 

 

 

 

 

 

 

 

 

References

WORSSAM, BC, ELLISON, RA and MOORLOCK, BSP. 1989. ‘Geology of the country around Tewkesbury’. Memoir of the British Geological Survey GB, Sheet 216, 57pp.

Click here to request data

Leinthall Earls Quarry

Exposed Units: Aymestry Limestone, Upper Ludlow Shales

Access: None – working quarry

This working quarry in the Aymestry Limestone and overlying Upper Ludlow Shales extracts up to 2000 tonnes of aggregate material per day, and is expected to continue producing for another 22-25 more years. The Leinthall Earls fault runs roughly SW to NE just south of the quarry and is downthrown to the south, which has resulted in a repeat of the Aymestry outcrop on the other side of the fault. There is also a smaller fault zone running through the middle of the quarry, which is oriented roughly perpendicular to the Leinthall Earls Fault.

The Aymestry Limestone at this site is massive, nodular and fossiliferous, with varying amounts of silty and muddy material.  The fossils generally occur in bands and are dominated by brachiopods, such as Kirkidium knighti, corals and crinoid ossicles. The Upper Bringewood Beds (Aymestry Limestone) are well developed at Leinthall Earls Quarry where there is a shallow anticline exposing a thickness of 40m.   The overlying Upper Ludlow Shales are more thinly bedded and gently dip down the slope, towards the east.  There are layers enriched in iron with examples of Liesegang bands and polygonal cracking on one bedding surface has been recorded.

Terminology

Downthrown – The side of a fault that has moved down relative to the other side of the fault.

Liesegang bands – Chemical bands in rocks (usually precipitations of iron), that developed after the formation of the rock and so are not dictated by sedimentary features, such as bedding.

Photos

View of quarry workings at Leinthall Earls Quarry.

General view of a worked face at Leinthall Earls Quarry, showing thickly-bedded, pale Aymestry Limestone overlain by finer-bedded, grey Upper Ludlow Shales.

 

 

 

 

 

 

 

 

 

References

Boynton, H.E. and Holland, C.H., 1997, ‘Geology of the Pedwardine District. Herefordshire and Powys’, Geological Journal, vol. 33 pp. 279-292

Boynton, H.E., 1979, ‘Studies of Kirkidium knighti (J Sowerby) from the beds near Ludlow, Shropshire’, Mercian Geology, vol. 7, pp. 181-190.

Click here to request data

Linton Quarry

Exposed Units: Much Wenlock Limestone, Upper Ludlow Shales, Downton Castle Sandstone

Conservation Status: Local Geological Site, SSSI

Access: Private Land

An interesting site that shows the relationship between the Wenlock, Ludlow and Pridoli units.

Starting at the bottom of the quarry and working upwards:

The Much Wenlock Limestone Formation (known locally as the Gorsely Limestone) is approximately 6m thick throughout the quarry. It is a thickly bedded limestone with a nodular appearance containing some irregular bands of silty material. Many fossils can be seen; brachiopods, corals and crinoid ossicles. At the top of this bed there is an unconformity represented by an irregular eroded surface. The unconformity represents a period of approximately 2 million years of missing rock units, in this case the Lower Ludlow Shales Group and Aymestry Limestone Formation.

The Upper Ludlow Shales is a much finer grained, bluish-grey limestone unit and is approximately 3.5m thick. The unit at this site is subdivided into the Lower and Upper Siltstones, which are separated from each other by the Lower and Upper Phosphatised Pebble Beds. The Lower Siltstones (approximately 1.4m thick) contain mainly shelly fauna in which brachiopods can be found.  Graptolite fossils have also been recorded at the site.  The Lower Phosphatised Pebble Bed is very thin (approximately 2-13mm thick) and consists of small brownish pebbles of siltstone and mudstone. The Upper Siltstones (approximately 2.1m thick) shows cross lamination and there are many fossiliferous layers which have weathered to a yellow-brown decalcified ‘rottenstone’. Fossils include brachiopods as well as acritarchs. The Upper Phosphatised Pebble Bed (approximately 2-7mm thick) contains rounded phosphatised siltstone and mudstone pebbles. This phosphatised bed is the equivalent of the Ludlow Bone Bed, found elsewhere on the Midland Platform.

The Downton Castle Sandstone Formation can be best seen on the western terrace. It is approximately 8m in thickness and consists of a lower shaley siltstone (approximately 1.4m thick) which shows fine laminations and cross bedding. Fossils found in the bed include brachiopods and plant remains. The Upper Sandstone (approximately 4.6m thick) is pale orange with darker spots and cross beds (ripples). The lower beds are thought to be marine, transgressing into the terrestrial sandstone.

This site is part of the Community Earth Heritage Champions Project.

Terminology

Unconformity – A boundary separating two or more rocks of markedly different ages, indicating a gap in geological time.

Acritarchs – Fossils of micro-organisms that are similar to phytoplankton and zooplankton.

Photo

General view of the quarry, facing East.

Unconformity between the Gorsley Limestone and Upper Ludlow Shales (facing SE) shown by the dashed yellow line.

Bedding and fine laminations in the Upper Ludlow Shales at Linton Quarry.

 

 

 

 

 

 

 

 

 

Cross-bedding in the Downton Castle Sandstone.

 

 

 

 

 

 

 

 

References

Aldridge, R et al. 2000, British Silurian Stratigraphy. Geological Conservation Review Series Volume 19. Joint Nature Conservation Committee.

Brenchley, P.J. and Rawson, P.F. 2006, The Geology of England and Wales. The Geological Society. The Geological Society Publishing House, Bath.

Cherns, L. 1980, Hardgrounds in the Lower Leintwardine Beds (Silurian) of the Welsh Borderland. Geological Magazine, Vol.117, no.4, pp. 311-408.

Lawson, J.D. 1954. The Silurian Succession at Gorsley (Herefordshire), Geology, Vol. 91, pp. 227-237.

Lawson, J.D., Curtis, M.L.K., Squirrell, H.C., Tucker. E.V. and Walmsley, V.G., 1982, The Silurian Inliers of the South-Eastern Welsh Borderland. Geologists’ Associations Guide No.5. The Geologists’ Association, London.

Squirrell, H.C. and Tucker, E.V., 1982, ‘Woolhope and Gorsley’, in Lawson, J.D., Curtis, M.L.K., Squirrel, H.C., Tucker. E.V. and Walmsley, V.G. (eds.), The Silurian Inliers of the south-eastern Welsh Borderland’, Geologists’ Association Guide No. 5, The Geoogists’ Association, London.

Woodcock, N. and Strachan, R. 2000, Geological History of Britain and Ireland. Blackwell Scientific Publications.

Worrsam, B.C. et al. 1989, Geology of the country around Tewkesbury. British Geological Survey Memoir.

Click here to request data

Lord’s Wood Quarry

Exposed Units: Llanelly Formation

Conservation Status: Local Geological Site

The Llanelly Formation at this site dips at about 16° south east and displays differing colours and textures of sandstones, nodular limestones and clay bands.  The units here are variably massive or thinly bedded, with a tendency for thinner beds to be sandy and yellow in colour.   A layer in the middle part of the sequence is very finely crystalline and contains voids in places where material has weathered out. These textures are markedly different from the surrounding rock layers and it is likely that this layer represents the remains of algal mats that developed in a shallow marine setting.

At the top of the exposed sequence, the limestones are nodular and are set within a blue/green clay matrix of striking colours. The formation of these nodular beds may be due to dewatering, soft sediment deformity, or a diagenetic effect.  Above the nodular bed, the beds become laminated, and have pronounced current ripple marks in profile, and obviously represent a change in conditions.

Terminology

Diagenesis (sic diagenetic) – A sequence of chemical reactions and processes that occur during the transition from sediment to sedimentary rock.

 

Photos

General view of the quarry face at Lord’s Wood Quarry.

 

 

References

Welch, F.B.A. and Trotter, F.M., 1961, Geology of the country around Monmouth and Chepstow, Memoir of the British Geological Survey, HMSO London

Coones, P., 1991, ‘A review of the stratigraphy and structure of the Lower Palaeozoic rocks in the Forest of Dean’, Proceedings of the Geologists’ Association, vol. 102, 1, pp. 1-24.

Click here to request data

May Hill Common Quarry

Exposed Units: Huntley Hill Formation

This quarry and the small adjacent pit are now very overgrown and the exposure limited.  The rock here is the Silurian Huntley Hill Formation, which consists of very coarse-grained sandstone containing pebbles of quartzite, pink feldspar and rare brachiopod fossils. The unit is thought to have been deposited in shallow marine conditions near to a shoreline.

The quarry itself is situated on the north east side of the May Hill Dome structure, a regional fold of Ordovician and Silurian sediments bound by the Blaisdon fault to the east and Glasshouse Fault to the north.

Photos

View of the small quarry working on May Hill Common showing a very overgrown site with little remaining exposure.

References

Aldridge, R.J., 1975, ‘The stratigraphical distribution of conodonts in the British Silurian’, Journal of the Geological Society of London, vol. 131, 6, pp. 607-618.

Click here to request data

Nash Quarry

Exposed Units: Folly Sandstone, Nash Scar Limestone, Coalbrookdale Formation

This is a large quarry in Nash Scar Limestone and Folly Sandstone with faulting associated with the Church Stretton Fault System.  Huge cliffs of crystalline limestone show corals, bryozoans and brachiopod fossils.  The older Folly Sandstone is seen in the core of an anticline.  Both rocks are affected by a variety of minor faults.  At this site the Folly Sandstone contains thick-bedded pebbly sandstones which have yielded some brachiopod fossils.

Nash Scar Limestone contains calcareous algae and bryozoan fossils within a coarse, calcite-bearing groundmass.  These algal limestones accumulated in an area of shallow sea, resulting from uplift along the line of the Church Stretton Fault.  The limestones are equivalent to the Woolhope Limestone.

The overlying Coalbrookdale Formation mudstones were formerly exposed to southeast of the site.

Photos

General view of the exposure at Nash Quarry.

The boundary between the interbedded sandstones and shales of the Folly Sandstone (bottom) and the overlying Nash Scar Limestone (top).

 

 

 

 

 

 

 

 

 

References

Hurst, J.M., Hancock, N.J. and McKerrow, WS. 1978. ‘Wenlock stratigraphy and palaeogeography of Wales and the Welsh Borderland’, Proceedings of Geologist’s Association, vol. 89, 3, pp. 197-226.

Pocock, R.W., Brammall, A. and Croft, W.N., 1940, ‘Easter field meeting, Hereford, 6 to 12 April 1939’,  Proceedings of Geologist’s Association, vol. 51, 1, pp. 52-62.

Woodcock, N.H. and Bassett, M.G. (eds)., 1993, Geological excursions in Powys, Central Wales, University of Wales Press, Cardiff, pp. 366.

Ziegler, A.M., Cocks, L.R.M. and McKerrow, W.S., 1968, ‘The Llandovery transgression of the Welsh Borderland’, Palaeontology, vol. 11, pp. 736-782.

Click here to request data

New House Farm Quarry

Exposed Units:  Yartleton Formation, Woolhope Limestone Formation

This is a quarry site, part of which is still active.  The main part of quarry, which predominantly extracted Woolhope Limestone, is long disused; virtually all of the Woolhope Limestone at this location has been quarried away, leaving the final excavation face near the junction of the Woolhope Limestone and Yartleton Formation.

A recent excavation has been made to produce stone by a farmer in the southernmost part of the quarry, providing an excellent new exposure in the top part of the Yartleton Formation. The uppermost 4m of the Yartleton Formation are currently exposed, with the very basal beds (only a few cms) of the Woolhope Limestone now visible.

The Yartleton Formation consists of fine-grained micaceous (mica-bearing) sandstone at the bottom of the exposure. This grades upwards into shelly, pebbly, fine-grained micaceous sandstones with lime cement and pebbles of micaceous siltstone.  The shelly sandstones contain moulds of abundant brachiopods and abundant burrow traces, which often lie parallel to the bedding.  The sandstones also contain abundant thin flat laminations and some cross laminations.

The small outcrop of Woolhope Limestone is composed of bioclastic limestones containing much crinoidal debris.

There are no key references for this site.

Terminology

Bioclastic limestone – A type of limestone characterised by very high fossil content.

Photos

General view of the exposure at New House Farm Quarry, showing flaggy sandstone beds that dip down towards the left (west) of the image.

Detail of flaggy bedding in the Yartleton Formation sandstones at New House Farm Quarry.

Close-up of a broken slab of Yartleton Formation sandstone.

 

 

 

 

 

 

 

 

 

Click here to request data

Quarry north of King Arthur’s Cave

Exposed Units: Gully Oolite Formation/Llanelly Formation

Conservation Status: Local Geological Site

This is a quarry in Gully Oolite Formation, a grey-white oolitic limestone containing occasional brachiopod and crinoid fossils.  In the middle section of the quarry, current bedding can be seen showing that these beds were formed in very shallow water.  At the southwestern end of the site, there are lenses of yellow sandstone.  The Llanelly Formation, seen at the very top of the quarry face, unconformably overlies the Gully Oolite Formation.  Between the Gully Oolite Formation and the Llanelly Formation there is a striking change in sedimentation which has been referred to as the ‘mid-Avonian break’.  The Llanelly Formation is a pale grey, thinly bedded, calcareous mudstone.

This site is part of the Community Earth Heritage Champions Project.

Terminology

Oolite – rock made up of ooliths, small spheres made up of successive concentric layers of calcium carbonate which accumulated as the ooliths rolled on the sea bed.

Photos

Sandstone lenses seen at the south east end of the quarry north of King Arthur’s cave.

East face of quarry showing Gully Oolite Formation. There are faint traces of current-bedding. Gully Oolite is overlain by thinly bedded Llanelly Formation at the very top of cliff.

General view of north face.

 

 

 

 

 

 

 

 

 

References

Dreghorn, W., 1968, Geology explained in the Forest of Dean and Wye Valley, David and Charles, Newton Abbot, pp. 196.

Howard, M.A., 1994, A landscape history of Ganarew, Herefordshire, Ross-on-Wye & District Civic Society, Ross-on-Wye, pp. 25.

Symonds, P.B., 1924, ‘King Arthur’s cave and the Great Doward’, Transactions of the  Woolhope Naturalists’ Field Club, vol. 25, 1, pp. 28-29.

Barton, R.N.E., 1995, ‘An interim report on the survey and excavations in the Wye valley, 1995′, Proceedings of the University of Bristol Spelaeological Society, vol. 20, 2, pp. 153-159.

Click here to request data

Rudge End Quarry

Exposed Units: Woolhope Limestone Formation

Conservation Status: Site of Special Scientific Interest

Rudge End Quarry is one of many small quarries situated on the Woolhope Dome inlier, an area of distinct hills to the south east of Hereford. Rudge End Quarry is on the southern side of the dome and rocks belonging to the Woolhope Limestone Formation outcrop within the site.

The rock face is approximately 110m in length and extends along the eastern edge of the site. The site is divided in two by a 2m drop in the middle section and this separates the northern rock face from the southern. Both rock faces are approximately 3m in height, apart from at the very bottom of the site where more of the quarry floor has been excavated, increasing the quarry face exposure to 6m.

The limestones found within the quarry are characterised by being nodular in appearance and are clay rich. Beds of limestones are interbedded with fine grained, rubbly siltstones. The northern rock face contains large beds of limestone with very thin rubbly siltstones at the base. The southern rock face also contains these large limestone beds, but there are less rubbly siltstones present.

Within the scree slopes found at the base of the northern rock face and on the slope opposite the rock face, marine fossils can be found. These include brachiopods and trilobites, as well as solitary and colonial corals.

In the northern rock face there is a small strike-slip fault, with slickensides present on the fault plane. These are present upon the fault plane indicating that there was a slight vertical movement, as well as horizontal movement. This is one of many faults in the area and is consistent with others that are nearby in the respect that it has a NE-SW orientation. This fault is parallel to the Rudge End Fault which is a complex fracture that separates the hills of Haugh Wood and Broadmoor Common.

This site is part of the Community Earth Heritage Champions Project.

Terminology

Inlier – An area of older rocks surrounded by younger rocks.

Fault – A line of weakness within the Earth’s crust along which movement and displacement occurs.

Strike-slip fault – A fault with the dominant component of displacement being lateral rather vertical.

Slickensides – Groves on a fault plane caused by frictional movement between rocks along the two sides of a fault. The direction of the grooves indicate the direction of the fault movement.

 

Photos

General View of exposure.

Well-bedded, nodular limestones of the Woolhope Limestone Formation.

Beds of the Woolhope Limestone Formation (looking East).

 

 

 

 

 

 

 

 

Solitary coral fossil found in the scree at Rudge End Quarry.

 

 

 

 

 

 

 

 

References

Aldridge, R. et al. 2000, British Silurian Stratigraphy, Geological Conservation Review Series Volume 19. Joint Nature Conservation Committee.

British Geological Society. 2001, Ross-on-Wye, England and Wales Series Sheet 215. Solid and Drift.

Herefordshire Nature Trust, 2003, Herefordshire Nature Trust Reserves Guide, Fifth Edition.  Herefordshire Nature Trust, Lower House Farm, Hereford.

Squirrell, H.C. and Tucker, E.V. 1960, The geology of the Woolhope inlier (Herefordshire), Quarterly Journal of the Geological Society, vol.116, 2, pp.139-185.

Woodcock, N. and Strachan, R. 2000, Geological History of Britain and Ireland, Blackwell Scientific Publications.

Click here to request data

Seven Sisters Cliff Quarries

Exposed Units: Avon Group, Black Rock Limestone, Gully Oolite

These are a substantial series of cliffs which have been quarried extensively in the past for aggregate, which is thought to have been transported over the River Wye to Hadnock. The cliffs expose about 12 m of Avon Group with 15m of the Black Rock Limestone above. A higher benched level may be formed of Gully Oolite. The Lower Limestone Shale consists of pale grey laminated shales with a silty horizon topped by massive grey dolomitised limestone with voids. Wavy bedding is apparent in places and stylolites have formed at the junction between dolomite beds.

Terminology

Dolomite – Carbonate mineral containing calcium and magnesium. Also used to define a rock type that is dominantly composed of this mineral.

Stylolites – Serrated surfaces that develop in sedimentary rocks which form when increased pressure causes part of the rock to dissolve (a process known as pressure solution).

Photos

The boundary between the Avon group (below, pale grey) and the Black Rock Limestone (above, darker grey).

General view of the exposure at Severn Sisters Cliff quarries.

 

 

 

 

 

 

 

 

 

References

Anon, 1970, ‘Geology of Symonds Yat and the Wye Gorge’, Forestry Commission, Coleford, pp. 8.

Dreghorn, W., 1968, ‘Geology explained in the Forest of Dean and Wye Valley’, David and Charles, Newton Abbot, pp. 196.

Millward, R. and Robinson, A., 1971, ‘The Wye Valley’, Macmillan, pp. 161-192.

Click here to request data

Shobdon Quarry

Exposed Units: Post-Anglian Deposits

Shobdon Quarry was formerly used for the extraction of gravels from the kettle moraine deposited on the withdrawal of the Late Devensian ice-sheet.  These gravels contain locally derived Lower Old Red Sandstone pebbles with smaller proportions of Silurian siltstones, sandstones, shales and greywackes from Central Wales, in addition to vein quartz and possibly dolerite and gabbro.

Originally, the exposures were up to 5.2m, consisting of undeformed sand and gravel – representing proglacial outwash deposits – overlying 3.5m of kettle moraine with interbedded sand and silt.  Small sections in the undeformed gravel still remain at the margins of the former workings.

As a tongue of the Wye glacier melted, it deposited blocks of ice against the line of hills stretching from Kington, past Shobdon to Orleton. These were then buried under the debris that was washed out of (and off of) the glacier. When the ice blocks melted, the overlying sediment collapsed and the resulting hollow is known as a kettle hole. Kettle moraine is the term given to a glacial landform that has been created through the development of multiple kettle holes. Many of these kettle holes contain ponds, as the underlying clay-rich glacial deposits prevent water from draining effectively.

Terminology

Greywacke – A type of sedimentary rock characterised by sand and gravel particles contained within a clay matrix and its formation is commonly associated with gravity flows, such as turbidity currents. Note: Greywackes are not equivalent to conglomerates or breccias as the processes of formation are different.

 

Photos

Pebbles and cobbles contained within the kettle moraine at Shobdon Quarry.

 

 

References

Dwerryhouse, A.R. and Miller, A.A., 1930, ‘The glaciation of Clun Forest, Radnor Forest and some adjoining districts’, Quarterly Journal of the Geological Society, vol. 86, 1, pp. 96-129.

Luckman, B.H., 1970, ‘The Hereford Basin’. in Lewis, C.A. (ed.), ‘The glaciations of Wales and adjoining regions‘, Longman Press, London, pp. 175-196.

Click here to request data

Slasher’s Quarry

Exposed Units: Malverns Complex, Hollybush Sandstone, Wyche Formation, Post-Anglian Deposits.

Conservation Status: Local Geological Site, SSSI, AONB

In Slasher’s Quarry, Precambrian Malverns Complex rocks were quarried for road stone.  The general view today is of green/grey-weathering, massive, jointed and sheared dioritic rocks with pink granitic (felsite) veins visible locally.  In the south-west corner, there are extensive outcrops of an ultrabasic rock, which consists almost entirely of the dark green mineral hornblende (the rock is known as a ‘hornblendite’), with small amounts white mica and even smaller amounts of pyrite and chalcopyrite.  The hornblendite is cut by later granite and quartz pegmatite veins and contacts with the other rocks are mainly faulted. At the northern end of the section, there is an example of one of the few well developed mineral veins intruded into the Malverns Complex, which consists mainly of pyrite and is in direct contact with quartzite.  In the north-east corner of the quarry, diorites are intruded by pink granite and later basalt/dolerite. A late fault striking north-south and dipping 45o to the west displaces these intrusions and shows evidence of some of the complex history of earth movements which have affected the rocks.

A fault line runs along the east side of the quarry separating the Malverns Complex from Cambrian Hollybush Sandstone in its east face.  These outcrops of dark green coloured sandstone are now rather overgrown.  There are also small outcrops of Silurian fossiliferous limestone in the north east face of the quarry. This unit has a basal limestone conglomerate containing pebbles of the underlying Hollybush Sandstone, on which it rests unconformably.  A rich fauna of brachiopods and conodonts, together with some graptolites found in the limestone, allow correlation of these beds with the Wyche Formation of Late Llandovery Series (Early Silurian) age.

About 4m of Head, formed by frost shattering and downslope movement of debris during recent ice-ages, are seen at the gate, and consist of red-brown silt with clasts of Malverns Complex.

Terminology

Ultrabasic – An igneous rock that is dominantly composed of iron and magnesium-rich minerals and contains only minor amounts of SiO­2-rich minerals, such as feldspar (they will never contain the mineral quartz).

Pyrite and chalcopyrite – Sulphide minerals of iron (or fool’s gold) and iron-copper respectively.

Conodonts – Teeth sets belonging to an extinct group of early vertebrates similar to the modern-day hagfish.

 

Photos

A view into Slasher’s Quarry from above the north face.

An outcrop of Cambrian Hollybush Sandstone on the east side of Slasher’s Quarry.

A view of the north face of Slasher’s Quarry.

 

 

 

 

 

 

 

 

References

Brooks, M. and Bassett, M.G., 1969, ‘New exposures of Cambrian and Llandoverian rocks in the southern Malvern Hills’, Proceedings of the Geological Society of London, no. 1660, pp. 361-362.

Bullard, D.W. 1989. Malvern Hills. A student’s guide to the geology of the Malverns. Nature Conservancy Council, Peterborough, pp.73.

Cowie, J.W. and Speedyman, D.L. 1977. The southern Malvern Hills, in Savage, R.J.G. (ed) Geological excursions in the Bristol district, University of Bristol, Bristol, pp. 3-15.

Jones, R.K., Brooks, M., Bassett, M.G., Austin, R.L. and Aldridge, R.J., 1969, ‘An Upper Llandovery limestone overlying Hollybush Sandstone (Cambrian) in Hollybush Quarry, Malvern Hills’, Geological Magazine, vol. 5, pp. 457-469.

Moorlock, B.S.P., 1986, British Geological Survey 1:10 000 geological sheet SO73 NE.

Worrsam, 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), British Geological Survey Press, London.

Click here to request data

Sutton Walls Hill Fort

Exposed Units: Post-Anglian Deposits

Conservation Status: Local Geological Site

The Post-Anglian Deposits exposed here have been classified as the Sutton Walls Member (which corresponds to the 4th terrace of the Lugg Valley Formation).  This is the oldest and highest of the river terraces in the Lugg Valley. Most of the gravels have been removed by quarrying but some can still be seen on either side of the trackway into the hill fort and under the ancient earthworks.

The unit comprises fine, well-bedded gravels and sands, with the coarser material typified by well-rounded to sub-rounded gravels (fragments less than 5cm diameter). The gravels are interbedded with sands that exhibit common permanganate staining and calcite precipitation.  Cross bedding is evident within the unit and indicates deposition by water current flowing SE and SW.  The lithologies are dominantly derived from north of the site and include Silurian sandstones and siltstones, Old Red Sandstone limestones  and sandstones, Lower Palaeozoic greywackes, rare coal clasts and Longmyndian (late Precambrian) igneous pebbles.

Terminology

Greywacke A type of sedimentary rock characterised by sand and gravel particles contained within a clay matrix and its formation is commonly associated with gravity flows, such as turbidity currents. Note: Greywackes are not equivalent to conglomerates or breccias as the processes of formation are different.

 

Photos

General view of overgrown outcrop of Post Anglian sand and gravel at Sutton Walls Hill Fort.

Detail of the exposure at Sutton Walls.

 

 

 

 

 

 

 

 

References

Brandon, A., 1989, ‘Geology of the country between Hereford and Leominster’. Memoir Geological Survey Great Britain, Sheet 198, 62pp.

Brandon, A., 1982, Quaternary deposits of sheet SO 54 (Hereford NE); explanation of 1:10000 sheets SO 54 NW, NE, SW and SE with special emphasis on potential resources of sand and gravel, British Geological Survey, (WA/VG/82/4), 40pp.

Luckman, B.H., 1970, ‘The Hereford Basin’, in Lewis, C.A. (ed), The glaciations of Wales and adjoining regions, Longman Press, London, pp. 175-196.

Richards, A.E., 1998, ‘Re-evaluation of the middle Pleistocene stratigraphy of Herefordshire, UK’, Journal of Quaternary Science, vol. 13, 2, pp. 115-136.

Click here to request data

Trippleton Lane

Exposed Units: Elton Formation (Lower Ludlow Shales), Upper Ludlow Shales

Conservation Status: Local Geological Site

A notable feature of this quarry is the absence of the Bringewood Formation and Aymestry Limestone that would normally lie in between the Lower and Upper Ludlow Shales. Instead, the Lower Leintwardine Formation of the Upper Ludlow Shales rests directly against the Elton Formation of the Lower Ludlow Shales. The contact between the two units is unfaulted and so represents an unconformity, or a time gap in the geological record.

All units here are dominated by grey or olive siltstone that is thinly bedded and often laminated. Thicker beds, up to 10cm, are in evidence and there are numerous examples of low angle current bedding. Harder grey nodules occur in places and there is one occurrence of a boulder with a siltstone drape. Some bedding planes contain abundant fauna, mainly small brachiopods and sparse graptolites, which correspond to the Lower Leintwardine Formation. This fossil assemblage continues along the outcrop for ~60 m where, on the right hand side, there is an abrupt lateral change to a soft khaki blocky mudstone with a prolific graptolite fauna. This lithology corresponds to the older Elton Formation. The sudden lateral change in lithology has been interpreted as a submarine channel, which was carved into the Elton Formation. This channel was then subsequently infilled by material from the younger Upper Ludlow Shales Group.

Photos

View along the land towards the quarry on Trippleton Lane.

Well-defined bedding in the Elton Formation.

A boulder lying in the bottom of the submarine channel, that has been buried by the Upper Ludlow Shales.

 

 

 

 

 

 

 

 

 

Current bedding in the Upper Ludlow Shales (in the thick bed to the right of the hammer shaft).

 

 

 

 

 

 

 

 

References

Allender, R., Holland, C.H., Lawson, J.D., Walmsley, V.G. & Whitaker, J.H.McD, 1960, ‘Summer Field Meeting at Ludlow’, Proceedings of the Geologists’ Association, vol.71, 2, pp.209-232.

Whitaker, J.H.McD., 1962, ‘The geology of the area around Leintwardine, Hertfordshire’, Journal of the Geological Society, vol. 118, 3, pp.319-351.

Click here to request data

Upper Hall Farm Quarry and Grasslands

Exposed Units: Much Wenlock Limestone, Elton Formation (Lower Ludlow Shales)

Conservation status: Site of Special Scientific Interest

Upper Hall Farm Quarry and Grasslands is a complex of quarries, woodland scrub and grassland on the slopes of the Silurian Limestone Hill to the west of the Malvern Hills. The locality shows the best exposure of the junction of the Wenlock and Ludlow series outside the Ludlow area. At this locality, the calcareous siltstones of the Lower Elton Formation rest conformably on the Much Wenlock Limestone Formation. This is the only locality in the Malvern Hills where the relationship between the representatives of two major divisions of the Silurian system can be studied and is thus significant in understanding the stratigraphy, structure and geological history of the area.

This quarry was opened in the upper part of the Much Wenlock Limestone Formation and the lower part of the Lower Elton Beds. The Much Wenlock Limestone consists of a 65-150m sequence of interbedded calcareous mudstones and nodular limestones. The latter form the bulk of the unit and vary from thinly bedded, argillacous limestones to massive limestones. Shale interbeds are common, where they generally appear somewhat squeezed and are frequently seen wrapping around lenses of limestone. An extensive fossil assemblage is present in the Much Wenlock Limestone at this locality and includes brachiopods, bryozoans (moss animals), stromatoporids (reef-forming organisms), corals, algae, trilobites and crinoids.

The Elton Formation is a medium grey, calcareous shaley mudstone with bands of nodular limestone common towards the base of the unit. Fossil assemblages in the unit are exceptionally preserved, but are not as diverse as the assemblages in the underlying Much Wenlock Limestone. The fossil assemblage is dominated by brachiopods but small solitary corals are also important, as are several species of ostracod, which are a type of microfauna belonging to the crustacean family.

Terminology

Argillacous – Containing clay minerals

 

Photos

General view of horizontally bedded Much Wenlock Limestone at Upper Halll Farm Quarry.

General view of nodular limestones of the Much Wenlock Limestone Formation.

View of the quarry face exposing the Much Wenlock Limestone and overlying Lower Ludlow Shales.

 

 

 

 

 

 

 

 

References

Anon, 1991, ‘SSSI notifications [OS 1:50000 sheet 149]‘, In Anon (eds), Statutory sites under the National Parks and Access to the Countryside Act 1949 and the Wildlife and Countryside Act 1981, English Nature, Peterborough.

Penn, J.S.W., and French, J., (1971), The Malvern Hills, Geologists’ Association Guides; Geologists’ Association.

Click here to request data

Upper Lyde Quarry

Exposed Units: Anglian Deposits (Risbury Formation, Portway Member), Post Anglian deposits

Conservation Status: Local Geological Site

In Upper Lyde Quarry there are well stratified gravels of variable coarseness and sorting, consist mainly of Old Red Sandstone clasts with Lower Palaeozoic and igneous lithologies comprising less than 5% of the small pebble fraction.  The large pebbles and cobbles are of sandstone and the smaller pebbles are of calcrete nodules.  Imbrication in the coarser beds indicates a current direction from south west to the north east

There are two units of gravels in the Portway to Burghill area, representing the final phase of wavering during the retreat of the Middle Pleistocene ice-sheet across Herefordshire.  The lower of two sequences of deposits is found on either side of a bedrock ridge at Upper Lyde and shows the development of an outwash plain.

The 8m section represents a cycle from finer layered gravels, through to coarser material including some boulders, and then a return to finer gravels and sandstones.  The change in grain size reflects changes in the carrying capacity of the meltwater that deposited the material. This sequence represents the change in the distance to the meltwater source at the ice-front, or perhaps, seasonal variations in meltwater production.  These gravels have been enclosed and subsequently deformed during a minor readvance of the Middle Pleistocene ice-sheet.

Terminology

Imbrication – The pebbles have been tilted in the direction of flow of the current.

Carrying capacity – A stronger flow of water is able to carry coarser sediment and vice versa.

Photos

General view of middle of pit at Upper Lyde Quarry.

 

References

Brandon, A., 1989, ‘Geology of the country between Hereford and Leominster’. Memoir of the Geological Survey of Great Britain, Sheet 198, British Geology Survey. London, pp. 62.

Richards, A.E., 1999, ‘Middle Pleistocene glaciation in Herefordshire: sedimentological and structural evidence from the Risbury Formation, Proceedings of the Geologists Association, vol. 110, pp. 173-192.

Richards, A.E., 1994, ‘The Pleistocene stratigraphy of Herefordshire’, Thesis, PhD, University of Cambridge.

Click here to request data

Whitman’s Hill Quarry

Exposed Units: Much Wenlock Limestone Formation, Coalbrookdale Formation

Conservation Status: Local Geological Site

Whitman’s Hill Quarry is located within a complex of faulted Silurian rocks just north of the Malvern Hills.

There are two rock formations present in the quarry: 12m of the Coalbrookdale Formation which forms the basal units, and 25m of the Much Wenlock Limestone Formation which sits above. The boundary between the two units represents a rapid decrease in sea levels in the area

The Coalbrookdale is characterised by olive grey to dark blue-grey silty mudstones with some calcareous siltstones and contain calcareous nodules and impersistent nodular calcareous beds. These beds are highly fossiliferous and contain a wide range of marine fauna, including brachiopods, trilobites, corals, calcareous algae, bivalves, orthocone nautiloids, crinoids and bryozoa. IN the eastern rock face at the bottom of the quarry are examples of spheroidal (‘onion skin’) weathering in the siltstones of the Coalbrookdale Formation. This weathering process has a produced ball-like structures ranging in size from 100mm to just over 2m.

The overlying Much Wenlock Formation is characterised by pale grey nodular to thinly bedded limestones. Some of the more nodular beds are known locally as the ‘Storridge Porridge’. The Much Wenlock Formation also contains small reef structures known as bioherms and one of these structures is found in the centre of the northern rock face

Within these two formations nine bentonite layers can be identified. These 2-3cm layers of fine clay are volcanic ash layers, formed when a volcano erupts and the ash is deposited on the surface of the sea. The ash sinks through the water column, killing much of the sea life. These soft bentonite layers are easily identified within the rock face as they have weathered preferentially in comparison to the harder limestones. Radiometric dating of uranium and lead in the bentonites yielded ages of around 425 million years for the deposition of these ash layers and demonstrates that the Coalbrookdale and Much Wenlock Formations were deposited around this time.

The nodular Much Wenlock Limestone (425 million years) was primarily quarried for aggregates and for the use in Lime Kilns. Eventually the underlying silty Coalbrookdale Formation (427 million years) was reached and quarry operations ceased, as the Coalbrookdale Formation is not a good aggregate material.

This site is part of the Community Earth Heritage Champions Project and the Whitman’s Hill Geodiversity Discovery Venture.

Terminology

Fault: A line of weakness within the Earth’s crust along which movement and displacement occurs

Photos

 

Whitmans Hill quarry aerial photograph.

Much Wenlock Limestone Formation overlying the Coalbrookdale Formation (Facing SE).

Ball of spheroidal weathering (Onion-skin) in Colbrookdale Formation unit.

Bioherm (reef mass) in Much Wenlock Limestone Formation on east face of the quarry.

Quarrying at Whitman’s Hill during Summer 1977.

South East corner of the quarry. From top of picture: Wenlock Limestone Formation with bentonite layer, then bentonite layer, then the base of the Much Wenlock Limestone Formation (with bentonite layers) above Coalbrookdale.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

References

Aldridge, R. et al. 2000, British Silurian Stratigraphy, Geological Conservation Review Series Volume 19, Joint Nature Conservation Committee.

Anon, 2007, ‘Mineralogical and geochemical investigations of bentonites from the Coalbrookdale and Much Wenlock Limestone Formations at Whitman’s Hill quarry, near Malvern’, Report for H&W EHT by HM Research Associates (Loughborough), 17pp.

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; HMSO, London

Brenchley, P.J. and Rawson, P.F., 2006, The Geology of England and Wales, The Geological Society, The Geological Society Publishing House, Bath.

Fleischer, M. and Altschuler, Z.S., 1986, The lanthanides and yttrium in minerals of the apatite group – an analysis of the available data. Neues Jahrbuch Mineralogische Monatschefte, vol. 10, pp. 467-480.

Jackson, J., 1997, Glossary of Geology, Fourth Edition. American Geological Institute.

Penn, J.S.W., 1969, ‘The Silurian rocks to the west of the Malvern Hills from Clencher’s Mill to Knightsford Bridge’. Thesis, PhD, University of London, pp. 145.

Penn, J.S.W., 1971, ‘Bioherms in the Wenlock Limestone of the Malvern area (Herefordshire, England)’. Mémoires du Bureau de Recherche Géologique et Minières, vol. 73, pp. 129-137.

Reeve, F.A.E., 1953, ‘The structure of the Silurian rocks of the Malvern and Abberley Hills, Worcestershire’. Thesis, PhD, University of Birmingham, pp. 286.

Rosenbaum, M., 2009, Balls in the Bank, Earth Matters, vo. 6, pp10.

White, D.E., 1991, ‘Additional palaeontological and biostratigraphical contributions to the 1:50000 sheet 199 (Worcester) memoir’. Report of the British Geological Survey, WH/91/147R, pp. 4.

Woodcock, N. and Strachan, R., 2000, Geological History of Britain and Ireland. Blackwell Scientific Publications.

Click here to request data

Wordell’s Farm Quarry

Exposed units: Elton Formation, Lower Ludlow Shales

This quarry exposes the Middle Elton Formation and Bringewood Formation of the Lower Ludlow Shales Group.

A low knoll conceals a rocky area which is the remnants of aggregate quarrying at this site.  The remaining quarry face is slightly curved, south facing and comprises a 15m length sloping 45°and up to 2m high.  A notable feature of this quarry is that it exposes a section through a filled-in river channel.  The Bringewood Formation here represents the infill of a river channel cut into the Middle Elton Formation.  This particular exposure is the furthest west of the system of similar channels in the Leintwardine area and also in Wigmore Rolls.

At its centre the quarry exposes boulders, blocks and pebbles in a sandy matrix beds.  There is a mixing of rounded boulders and completely angular blocks, which may be finely grained or coarsely crystalline and at different attitudes, showing that they have been carried into place.  The limestone contains fossils including corals, brachiopods, stromatoporoids, bryozoans, orthocones, gastropods and crinoid ossicles.

The channel deposits are flanked on either side by normal bedded sediments of low dip.  These are the Middle Elton Formation and are characterised at this site by thinly bedded, soft and flaggy mudstones.

Photos

Middle Elton Formation at the left side of channel.

Boulder beds in the channel.

 

 

 

 

 

 

 

References

Boynton, H.E. and Holland, C.H., 1997, ‘Geology of the Pedwardine district, Herefordshire and Powys’, Geological Journal, vol. 32, 3, pp. 279-292.

Click here to request data