Farrant, A R. 2008. A walkers' guide to the geology and landscape of western Mendip. (Keyworth, Nottingham: British Geological Survey.) ISBN 978 085272576 4

The guide is available to purchase from the British Geological Survey https://shop.bgs.ac.uk/Shop/Product/BSP_BWMEND

Figures

(Figure 1) Lion. On contents page.

(Figure 2) Contact Mendip Hills.

(Figure 3) Geological timescale.

(Figure 4) Block diagram of a pericline.

(Figure 5) Thrust faulting and folding in the Mendips.

(Figure 6) Avon Group.

(Figure 7) Portishead Formation.

(Figure 8) Black Rock Limestone, Burrington Oolite, Clifton Down Limestone, Brachiopods in Oxwich Head Limestone.

(Figure 9) Quartzitic Sandstone, Dolomitic Conglomerate, Mercia Mudstone.

(Figure 10) Langport Member and Westbury Formation, Lias Group, Harptree Beds.

(Figure 11) Limits of glaciation.

(Figure 12) A diorama of ice-age life in the Mendips.

(Figure 13) Cave bear.

(Figure 14) A galena vein, Star Mine, Shipham. © Chris Binding.

(Figure 15) An example of galena.

(Figure 16) Dumper truck, Whatley Quarry.

(Figure 17) Aerial view of Cheddar Gorge.

(Figure 18) Geology of Cheddar Gorge.

(Figure 19) Cross-section of the gorge and cave systems.

(Figure 20) Schematic diagram showing cave development in the Mendips.

(Figure 21) Hibernating horseshoe bats. © Tessa Knight.

(Figure 22) Cheddar Gorge as it is today.

(Figure 23) Maerz lime kiln at Batts Coombe Quarry, 1974. © National Stone Centre.

(Figure 24) Cheddar pink. © Sharon Pilkington.

(Figure 25) Aerial view of The Charterhouse.

(Figure 26) Worked-out lead rakes, Ubley Warren.

(Figure 27) Charterhouse mine workings (after University of Bristol Spelaeological Society Proceedings, 1986).

(Figure 28) Gruffy ground, Velvet Bottom.

(Figure 29) Upper Flood Swallet © Peter Glanvill.

(Figure 30) Alpine penny-cress. © Sharon Pilkington.

(Figure 31) Slag left from the 19th century resmelting operations, Blackmoor.

(Figure 32) Examples of complete crinoids, Black Rock Limestone.

(Figure 33) Black Rock Quarry. Close up of ooliths in the Burrington Oolite.

(Figure 34) Long Wood Swallet.

(Figure 35) Grimmia donniana growing on glassy lead-rich slag. © Sharon Pilkington.

(Figure 36) The summit of Blackdown, 325 m above sea level.

(Figure 37) Aerial phototograph of the Blackdown area.

(Figure 38) Heathland developed on the impermeable Portishead Formation sandstone.

(Figure 39) View from the top of Blackdown towards Dolebury Warren.

(Figure 40) Plan of GB Cave and Charterhouse Cave, after University of Bristol Spelaeological Society.

(Figure 41) A deep sinkhole, formed when the ground collapsed into the underlying cave after heavy rain in 1968.

(Figure 42) Bat Passage, GB Cave. © Peter Glanvill.

(Figure 43) Black Rock Limestone with abundant fossil crinoid fragments.

(Figure 44) Mineshaft, GB Gruffy Field Nature Reserve.

(Figure 45) Aerial phototograph of the Blackdown area.

(Figure 46) The ‘Rock of Ages’, a crag of Burrington Oolite. The story of the Rev. Toplady sheltering here, prompting his famous hymn, is probably not true.

(Figure 47) The main scarp in Burrington Combe, formed of the Black Rock Limestone.

(Figure 48) Mesolithic cave art in Aveline’s Hole. A series of inscribed crosses can be seen scratched into the rock. Photo © University of Bristol Spelaeological Society.

(Figure 49) Young caver in Goatchurch Cavern. © Peter Glanvill.

(Figure 50) Geological map of the Burrington area showing the caves, springs and postulated underground drainage routes. Adapted from University of Bristol Spelaeological Society Proceedings, 1992.

(Figure 51) The East Twin Brook, flowing off the sandstone uplands of Blackdown.

(Figure 52) The steep south-facing slope of Burrington Combe, a haven for lime-loving plants.

(Figure 53) Fossil brachiopod Syringothyris, common in the Black Rock Limestone.

(Figure 54) The Clifton Down Limestone locally contains fossil corals such as this example of Lithostrotion, a colonial coral now extinct.

(Figure 55) View of Burrington Combe from Blackdown, overlooking the Vale of Wrington to the limestone uplands of Broadfield Down.

(Figure 56) Lower Carboniferous coral (Palaeosmilia murchisoni).

(Figure 57) A stone wall in Rowberrow made up of grey Carboniferous Limestone, dark red sandstones of the Portishead Formation, and thin slabs of pinkish Triassic Dolomitic Conglomerate.

(Figure 58) North–south cross-section from Shipham Gorge to Churchill Gate. Mineral veins bearing lead and zinc ore penetrate up though the Portishead Formation and into the Dolomitic Conglomerate. Near-surface weathering has altered and enriched the primary ores into the workable ore deposits exploited by miners in the 17th and 18th centuries.

(Figure 59) Aerial phototograph of the Shipham and Rowberrow area.

(Figure 60) An area of ‘gruffy ground’, a local name for areas of old mine workings, trial pits, spoil heaps and mine shafts on the south-east side of Shipham.

(Figure 61) Rowberrow Bottom.

(Figure 62) Rowberrow Bottom. The stream here is flowing on the impermeable sandstones of the Portishead Formation.

(Figure 63) Old limekiln, Rowberrow Bottom.

(Figure 64) View from Crook Peak, looking east. The peak is a crag of dipping Burrington Oolite limestone.

(Figure 65) Cross-section across Axbridge Hill. For abbreviations see map key. [ST 430 544] to [ST 430 575]. Vertical exaggeration x 2.

(Figure 66) Aerial phototograph of South flank: Crook Peak.

(Figure 67) Shute Shelve railway tunnel, a good exposure of the Black Rock Limestone on the cycle track between Axbridge and Winscombe.

(Figure 68) Fragments of yellow and red ochre, once dug from many small pits and mines on Axbridge Hill.

(Figure 69) Many small ferns and plants such as these love the thin rocky calcareous soils developed on the Carboniferous Limestone. © Sharon Pilkington.

(Figure 70) Shipham Perch Quarry. A small quarry in the Burrington Oolite, with a prominent red-stained fault breccia exposed at the top of the quarry.

(Figure 71) Large vertical kilns at Callow Rock, Cheddar. © National Stone Centre.

(Figure 72) Bristol diamonds' quartz crystals lining a geolode or 'potatoe stone'.

(Figure 73) Aerial phototograph of North flank: Banwell.

(Figure 74) Stacked bones in Banwell Bone Cave. © John Chapman.

(Figure 75) Cross-section of Sandford Hill. For abbreviations see map key. [ST 424 584] to [ST 424 596] Vertical exaggeration x 4.

(Figure 76) Steeply dipping limestone, Sandford Quarry.

(Figure 77) Cross-section through the Churchill nappe. South [ST 444 587], North [ST 444 606].

(Figure 78) View across Dolebury Warren, towards Blackdown.

(Figure 79) Overturned strata, Churchill rocks.

(Figure 80) Aerial phototograph of the Priddy area.

(Figure 81) Geological cross-section from Priddy to Stock Hill Forest. West [ST 525 513], East [ST 570 517] Vertical exaggeration x Folding in the Black Rock Limestone, Swildon’s Hole.

(Figure 82) Folding in the Black Rock Limestone, Swildons Hole.

(Figure 83) Map of cave systems, mines and veins.

(Figure 84) St Cuthbert’s Lead Works, in the Priddy Minery, c. 1903. Courtesy John Cornwell collection.

(Figure 85) Waldegrave Pool.

(Figure 86) Draycott Sleights reserve, with dipping Burrington Oolite. © Sharon Pilkington.

(Figure 87) Aerial photograph of the South Flank: Draycott.

(Figure 89) Draycott Marble Quarry. Courtesy J. hanwell Collection.

(Figure 91) Hyena, which once roamed across Mendip.

(Figure 92) Cave bear tooth from Westbury-sub-Mendip.

(Figure 93) Topographical map of closed depressions.

(Figure 94) Cross Swallet, a large closed basin near Westbury-sub-Mendip.

(Figure 96) The River Axe emerges from its journey underground at the mouth of Wookey Hole.

(Figure 97) Aerial photograph Wookey Hole and Ebbor Gorge.

(Figure 98) Wookey Chamber Nine. This large chamber is the furthest point in the show cave. The lake is the underground River Axe.

(Figure 99) Cross-section showing the course of the water from Swildon’s Hole, Priddy through to the resurgence at Wookey Hole, with former water tables shown.

(Figure 100) Ebbor Gorge. This rocky ravine is a National Nature Reserve owned by the National Trust. The reserve supports a wide variety of flora and fauna.

(Figure 102) The Milton Lane section. The track here exposes a section of the basal Jurassic strata, here consisting of interbedded limestone and mudstone.

(Figure 103) Aerial photograph Wells.

(Figure 104) View of the cathedral and Glastonbury Tor.

(Figure 105) Wells Cathedral from the east side. The large ponds in the foreground are the St Andrews Risings, a large karst spring draining the hills to the east of Wells.

(Figure 106) The Wells and Mendip Museum, which houses many exhibits showing the geology, archaeology and natural history of the Mendip Hills.

(Figure 107) The Clifton Down Limestone on Tor Hill contains fossil stromatolites, a type of algal structure today only found in hypersaline lagoons.

(Figure 108) Dulcote Quarry used to be the source of Dulcote geodes, formed by the replacement of anhydrite nodules by quartz. © David Roche Geoconsulting. Scalee: 0 22 millimetres.

(Figure 109) Dulcote Quarry, [117] [ST 56859 44146] near Wells. Here the Carboniferous Limestone strata have been so severely folded the rocks are vertical or even overturned.

(Figure 110) Aerial photograph North Flank: Harptree and Smitham Hill.

(Figure 111) This aqueduct, part of the Bristol Water’s ‘line of works’ takes water from springs around Chewton Mendip to the water treatment plants at Barrow Gurney.

(Figure 112) The drystone walls on Smitham Hill contain large blocks of silicified Harptree Beds chert, with many lichens and small ferns thriving on the lime mortar.

(Figure 113) Smitham Chimney, the last remaining lead-smelting chimney on Mendip, restored in the 1970s by the Mendip Society.

(Figure 114) Water conduit, made from the Blue Lias limestone, Wells.

(Figure 115) Dipping Burrington Oolite exposed at Black Rock, near Cheddar.

(Figure 117) Humps mark the line of a World War II bombing decoy leading up to the summit of Blackdown.

(Figure 118) Priddy Mineries.

(Figure 122) West front, Wells Cathedral.

(Figure 123) Green Lane, Axbridge Hill.

(Front cover) Front cover.

(Rear cover) Rear over.