Figures and tables
Figures
(Figure 1.1) Simplified sketch map showing the principal Devonian outcrops'of Great Britain. Marine Devonian strata are confined to south-west England, the remainder being sedimentary rocks of Old Red Sandstone facies and volcanic rocks. Caledonian (Ordovician to Late Devonian) intrusive rocks are not shown.
(Figure 1.2) Stratigraphical distribution of the main Old Red Sandstone sequences of Great Britain. Tectonic events and their timing are from Soper and Woodcock (2003). Ages are from Williams et al. (2000). Small solid bars indicate the principal volcanic rocks. Individual chapter introductions provide more detailed stratigraphical distribution charts. (HV — Hoy Volcanic Member; MF — Mell Fell Conglomerate Formation; RC Ridgeway Conglomerate Formation.)
(Figure 1.4) Major subdivisions of the Old Red Sandstone and its chronostratigraphical classification. Ages from Williams et al. (2000).
(Figure 1.3) Sketch maps showing the movements and amalgamation of the early Palaeozoic continents that produced the Old Red Sandstone (Laurussia) continent. (a) and (b) are global views to illustrate the fragmentation of Avalonia from Gondwana and its drift northwards as the Iapetus Ocean closed (adapted from Torsvik et al., 1992, by Trench and Torsvik, 1992). (c), (d) and (e) show the later stages of the Caledonian Orogeny. Sinistral strike-slip movements in relation to the Laurentian margin culminated in the Acadian Orogeny in late Early Devonian (Emsian) times (after Stephenson et al., 1999, adapted from Soper et al., 1992).
(Figure 2.1) Generalized Mid-Devonian palaeogeography based on present geography of northern Scotland. After Trewin and Thirlwall (2002).
(Figure 2.2) Old Red Sandstone outcrops in the Orcadian Basin and restoration of strike-slip displacements in the Shetland Islands. Based on Mykura and Phemister (1976) and Anderton et al. (1979).
(Figure 2.3) Cyclic lacustrine facies in the Caithness Flagstone Group. After Trewin and Thirlwall (2002), from Donovan (1980).
(Figure 2.4) Stratigraphical successions in northern Scotland showing positions of the GCR sites described. (1 — Melby; 2 — Footabrough to Wick of Watsness; 3 — Easter Rova Head; 4 — The Cletts, Exnaboe; 5 — Old Man of Hoy Coast; 6 — South Stromness Coast Section; 7 — Yesnaby and Gaulton Coast Section; 8 — Bay of Berstane; 9 — Greenan Nev Coast, Eday; 10 — South Fersness Bay, Eday; 11 — Taracliff Bay to Newark Bay; 12 — Red Point; 13 — Pennyland (Thurso–Scrabster); 14 — Achanarras Quarry; 15 — John o'Groats; 16 — Wick Quarries; 17 — Sarclet; 18 — Tarbat Ness; 19 — Tynet Burn; 20 — Den of Findon; 21 — Dun Chia Hill (Loch Dunteichaig); 22 — Rhynie.)
(Figure 2.5) Geological sketch map of the outcrops of Old Red Sandstone rocks in Shetland and their structural relationships; with locations of GCR sites. After Mykura and Phemister (1976).
(Figure 2.6) Geological sketch map of Orkney with locations of GCR sites, indicated in bold typeface. After Mykura and Phemister (1976).
(Figure 2.7) Old Red Sandstone outcrops in north-east Scotland and locations of GCR sites.
(Figure 2.8) Geological sketch map of the Melby Formation on Shetland Mainland. After Mykura and Phemister (1976).
(Figure 2.9) Cross-bedded sandstones between Ayre of Huxter and Lang Rigg. (Photo: P. Stone.)
(Figure 2.10) Stratal settings of the Melby fish beds. After Mykura and Phemister (1976), reproduced from Dineley (1999a).
(Figure 2.11) Sandstones between the two Melby fish beds. (a) Pobie Skeo; (b) large-scale planar cross-bedding; (c) small-scale trough cross-bedding. (Photos: P. Stone.)
(Figure 2.12) The Upper Melby Fish Bed, Rotten Craig. (a) Laminated mudstones with dolomitic layers; (b) convolute lamination in thin sandstone bed; (c) rippled siltstone bedding surface. (Photos: P. Stone.)
(Figure 2.13) The Walls Formation at Cotti Geo, Ram's Head. (Photo: P. Stone.)
(Figure 2.14) Major stratigraphical and structural features of the Walls Peninsula. After Mykura (1976).
(Figure 2.15) (a) Sketch map of the rocks of the Walls Formation exposed on the coast between Ram's Head and The Flaes. (b) Cross-section showing the structural pattern between Ram's Head and The Flaes. After Mykura and Phemister (1976).
(Figure 2.16) Rippled bedding surfaces in the Walls Formation. (Photo: P. Stone).
(Figure 2.17) Examples of lithofacies associations in the Walls Formation. After Melvin (1985).
(Figure 2.18) Outline geology of the Rova Head area. After Allen (1981a).
(Figure 2.19) Variably matrix- and clast-supported conglomerates with sandstone interbeds of the Rova Head Conglomerate Formation. (Photo: P. Stone.)
(Figure 2.20) Graphic logs of part of the ;?(Iva Head succession. See (Figure 2.18) for the location of sections A and B. After Allen (1981a).
(Figure 2.21) Clast-supported conglomerates of the Rova Head Conglomerate Formation forming cliffs at Rova Head. (Photo: P. Stone.)
(Figure 2.22) Geological map of the Old Red Sandstone of south-east Shetland Mainland and detailed map of the Clefts GCR site. After Mykura (1976).
(Figure 2.23) Conglomerates at Vaakel Craigs. (Photo: P. Stone.)
(Figure 2.24) Planar cross-bedded, probably aeolian, sandstones, Three Steps Geo. (Photo: P. Stone.)
(Figure 2.25) The Cletts (bedding plane of pebbly sandstone, left), and gully eroded through the fish bed. (Photo: P. Stone.)
(Figure 2.26) Disrupted dolomitic layers in lacustrine laminites. Exnaboe Fish Bed at The Cletts. (Photo: P. Stone.)
(Figure 2.27) Geological map of the Stromness coast area. After British Geological Survey (1999).
(Figure 2.28) Upper Stromness Flagstone Formation at Warebeth. View south-west towards Hoy. (Photo: E.A. Pickett.)
(Figure 2.29) Geological map of the Taracliff Bay to Newark Bay area. Based on Kellock (1969) and British Geological Survey (1999).
(Figure 2.30) Load structures and convolute bedding in the Eday Flagstone Formation near Muckle Castle, south-west of Newark Bay. (Photo: BGS No. D1522, reproduced with the permission of the Director, British Geological Survey, © NERC.)
(Figure 2.31) Geological sketch map of the Greenan Nev area. After British Geological Survey (1999).
(Figure 2.32) Interbedded red marl and sandstone of the Eday Marl formation at Greenan Nev. View towards the north-east. (Photo: E.A. Pickett.)
(Figure 2.33) Geological sketch map of the south-west side of Fersness Bay. Based on Mykura (1976) and British Geological Survey (1999).
(Figure 2.34) Middle Eday Sandstone Formation at Fersness Bay showing cross-bedding, convolute bedding and calcareous weathering. View towards the ENE. (Photo: E.A. Pickett.)
(Figure 2.35) Geological map of the Yesnaby coast, west Mainland. Based on Fannin (1970), Mykura (1976), Clarke (1990) and British Geological Survey (1999).
(Figure 2.36) Cliffs of large-scale cross-bedded sandstones of the Qui Ayre Sandstone Formation at Yesnaby. In the background is Garthna Geo with exposed basement. View towards the south. (Photo: BGS No. D1545, reproduced with the permission of the Director, British Geological Survey, © NERC.)
(Figure 2.37) (a) Simplified geological map of north-west Hoy (after British Geological Survey, 1999). (b) Detailed geological map of the northern part of the GCR site (after Mykura, 1976).
(Figure 2.38) The Old Man of Hoy, a sea stack of Hoy Sandstone Formation lying just off the spectacular cliffs of north-west Hoy. The basal member, the Hoy Volcanic Member, lies at the base of the stack where it overlies the Upper Stromness Flagstone Formation. (Photo: BGS No. D1539, reproduced with the permission of the Director, British Geological Survey, © NERC.)
(Figure 2.39) Geological map of the Bay of Berstane area. After British Geological Survey (1999)
(Figure 2.40) Grey-green mudstone unit within the Eday Marl Formation at the Bay of Berstane. (Photo: J.E.A. Marshall.)
(Figure 2.41) Locality map of the Red Point area. Based on Donovan (1975) and Trewin (1993).
(Figure 2.42) Cross-section of Red Point area to illustrate basement margin features. Based on Donovan (1980) and Trewin (1993).
(Figure 2.43) Coarse breccia of basement and limestone clasts in a sandy matrix, overlying massive limestone, Red Point. (Photo: P. Stone.)
(Figure 2.44) Breccia tongues interfingering with sandstone. (a) General view; (b) detail. (Photos: P. Stone.)
(Figure 2.45) Locality map of Pennyland GCR site.
(Figure 2.46) Styles of shrinkage cracks affecting, thinly bedded mudstones and fine-grained sandstones. (a) Polygonal array of desiccation cracks; (b) more widely spaced orthogonal array of desiccation cracks; (c) lenticular shrinkage cracks forming complex interlocking pattern. (Photos: P. Stone.)
(Figure 2.47) Compressed, deformed shrinkage cracks in cross-section. (Photo: BGS No. P547102, reproduced with the permission of the Director, British Geological Survey, © NERC.)
(Figure 2.48) Load-induced 'pseudonodule' layer. (Photo: P. Stone.)
(Figure 2.49) Map of the John o'Groats-Duncansby Head area. Based on British Geological Survey 1:50 000 Sheet 116 (Scotland), Wick (1985) and Trewin (1993).
(Figure 2.50) Map of the Wick Quarries GCR site.
(Figure 2.51) (a) Laminated mudstones and thin sandstones of the Lower Caithness Flagstone Group, South Head. (b) Detail of laminites, Lower Caithness Flagstone Group, South Head. (Photos: P. Stone.)
(Figure 2.52) Desiccation polygons, Wick Quarries, South Head, Wick. (Photo: P. Stone.)
(Figure 2.53) Laminites of mudstone, sandstone and dolostone, Wick Quarries. (a,b) Small-scale recumbent shortening structures; (c) small-scale brittle extensional faults. (Photos: P. Stone.)
(Figure 2.54) Rippled sandstone surface, Wick Quarries. (Photo: P. Stone.)
(Figure 2.55) Geology of the Achanarras area and location of the Achanarras Quarry GCR site.
(Figure 2.56) Part of the disused Achanarras Quarry, now flooded, showing the upper 50 cm of the Achanarras Limestone Member overlain by the basal beds of the Upper Caithness Flagstone Group. (Photo: P. Stone.)
(Figure 2.57) Section at Achanarras Quarry. After Trewin (1986, 1993).
(Figure 2.58) Geological map of the Sarclet area. After British Geological Survey 1:50 000 Sheet 110 (Scotland), Latheron (1985).
(Figure 2.59) Sarclet Sandstone Formation. Deformed sandstones rest on a bedding-parallel detachment; a low-angle dislocation cuts the regularly bedded sandstone below the detachment. (Photo: P. Stone.)
(Figure 2.60) Geological map of the Tarbat Ness area.
(Figure 2.61) Tarbat Ness Formation. (a) Conglomerate lenses; (b,c) pebbly layers and isolated pebbles in cross-bedded sandstones (Photos: P. Stone.)
(Figure 2.62) Tarbat Ness Formation. (a) Tabular cross-bedding; (b) sand volcano. (Photos: P. Stone.)
(Figure 2.63) (a) Thinly Gaza Formation west of Canas Solais. (b) 'Adhesion warts' in the Gaza Formation near Castlehaven. (Photos: P. Stone.)
(Figure 2.64) Palaeoenvironmental model for the Upper Old Red Sandstone of Tarbat Ness. After Marshall et al. (1996).
(Figure 2.65) Map of the area around Dun Chia hill, at the south-west end of Loch Duntelchaig. After British Geological Survey 1:50 000 Sheet 73W (Scotland), Foyers (1996).
(Figure 2.66) The cliffs of Creag nan Clag, on the eastern flank of Dun Chia hill. The undulating unconformity between Middle Old Red Sandstone massive breccio-conglomerates and underlying flaggy psammites of the Grampian Group (Dalradian) can be traced for 1300 m along the base of the steep upper cliffs. (Photo: BGS No. D1813, reproduced with the permission of the Director, British Geological Survey, NERC.)
(Figure 2.67) Sketch map of Tynet Burn: (A) section cleared in 1996 (Trewin and Davidson, 1999); (B) section excavated in 1989–1990 (Wood and Norman, 1991). Based on Peacock et al. (1968) and Davidson and Trewin (1999).
(Figure 2.68) (a) Composite log of succession in Tynet Bum between points (A) and (C) on (Figure 2.67). The position of the Coccosteus Bed is inferred. (b) Summary log of section excavated at Point (A). After Trewin and Davidson (1999).
(Figure 2.69) Field sketch of exposure at Point A in Tynet Burn showing the disrupted nature of the Upper Nodule Bed. After Trewin and Davidson (1999). This exposure is now largely obscured by talus and vegetation.
(Figure 2.70) Geological map of the Gamrie–New Aberdour area. Based on Institute of Geological Sciences 1:50 000 Sheet 96 (Scotland), Banff (1955) and British Geological Survey 1:50 000 Sheet 97 (Scotland), Fraserburgh (1987).
(Figure 2.71) Sketch of the lower part of the cliff near Pennan [NJ 842 658] showing the unconformity between the Lower Old Red Sandstone (Crovie Group) and overlying Middle Old Red Sandstone ((Findon Group). The faults in the Crovie Group do not all appear to affect the Findon Group, the basal conglomerates of which fill hollows eroded along the faults. The Crovie Group was therefore faulted and eroded prior to the deposition of the conglomerates. After Trewin (1987a).
(Figure 2.72) Geological map of the area of the Rhynie GCR site. Inset maps show location of the figure. After Rice et al. (2002). See Rice and Ashcroft (2004) for a new structural interpretation of the northern part of the basin.
(Figure 2.73) Generalized stratigraphy and basin correlations of the Rhynie Basin. After Rice et al. (2002).
(Figure 2.74) Evolution of the Rhynie Basin and hot spring development. After Rice et al. (2002).
(Figure 2.75) Cartoon view looking north to illustrate the Rhynie hot spring system and the low-angle sinter apron crossed by streams emanating from hot spring vents. Plants colonized the apron along stream banks and ponds, and on alluvial floodplain areas. The sinter apron was periodically flooded by waters from the axial river system. Some coarse detritus and reworked volcanic ejecta were sourced from the west. After Trewin and Wilson (2004).
(Figure 3.1) Old Red Sandstone outcrops in the Midland Valley, showing locations of GCR sites: (1 — The Toutties; 2 — Dunnottar Coast Section; 3 — Crawton Bay; 4 — North Esk River; 5 — Milton Ness; 6 — Aberlemno Quarry; 7 — Tillywhandland Quarry; 8 — Whiting Ness; 9 — Tay Bank; 10 — Glen Vale; 11 — Wolf's Hole Quarry; 12 — Auchensail Quarry; 13 — Siccar Point to Hawk's Heugh; 14 — Largs Coast, Ayrshire; 15 — North Newton Shore, Arran). After British Geological Survey 1:625 000 Solid Geology Map, UK North Sheet, 4th edn (2001).
(Figure 3.2) Lithostratigraphical groups of the Old Red Sandstone of the Midland Valley. After Browne et al. (2002).
(Figure 3.3) Old Red Sandstone basins in the Midland Valley.
(Figure 3.4) Palaeogeographical development of the Midland Valley and adjacent areas. (a) Early Wenlock; (b) Mid-Přídolí. (a) after Bassett et al. (1992); (b) after Bluck et al. (1992). Palaeogeographical development of the Midland Valley and adjacent areas. (c) Early Devonian (Lochkovian); (d) Early Devonian (late Pragian–early Emsian); (e) Mid-Devonian (Givetian); (t) Late Devonian (Frasnian–early Famennian). After Bluck et al. (1992).
(Figure 3.5) Sections of the Late Silurian–Early Devonian rocks in the northern Midland Valley. After Browne et al. (2002).
(Figure 3.6) Outcrops of the Lanark Group in the southern Midland Valley and schematic cross-section. After Browne et al. (2002).
(Figure 3.7) Sections of the Late Devonian Stratheden Group in the Midland Valley showing stratigraphical positions of GCR sites. Inset shows outcrop of Stratheden Group and locations of sections. After Browne et al. (2002).
(Figure 3.8) Geological sketch map of the area of The Toutties GCR site. After British Geological Survey, 1: 10 000 Manuscript Map NO 88NE (1996).
(Figure 3.9) (a) Vertical section of the Cowie Sandstone Formation; and (b) detailed section at The Toutties. Based on Armstrong et al. (1978b) and Dineley (19996).
(Figure 3.10) Cowie Harbour Fish Bed [NO 8813 8667]. Fissile mudstones and siltstones with thin ripple-laminated sandstone. (Photo: BGS No. D2455, reproduced with the permission of the Director, British Geological Survey, © NERC.)
(Figure 3.11) Geological map of the area of the Dunnottar Coast Section, from Downie Point to Crawton Bay, with generalized vertical section of the strata. After British Geological Survey 1:50 000 Sheet 67 (Scotland), Stonehaven (1999).
(Figure 3.12) Sub-vertical conglomerates of the Castle Haven Conglomerate Member of the Dunnottar Castle Conglomerate Formation at Dunnottar Castle [NO 882 839]. (Photo: BGS No. D5187, reproduced with the permission of the Director, British Geological Survey, © NERC.)
(Figure 3.13) Model for Lower Old Red Sandstone sedimentation in the northern Midland Valley. After Houghton and Bluck (1988).
(Figure 3.14) Geological sketch map of the Crawton Bay area. After Stephenson et al. (1999, fig. 9.19).
(Figure 3.15) Coarse conglomerates of the Crawton Volcanic Formation resting on the eroded top of the third lava. (Photo: N.H. Trewin.)
(Figure 3.16) Geological sketch map of the North Esk River section.
(Figure 3.17) Coarse clast-supported orthoconglomerate of the Gannochy Conglomerate Formation at Loups Bridge, North Esk River. (Photo: BGS No. D5347, reproduced with the permission of the Director, British Geological Survey, © NERC.)
(Figure 3.18) Location and geological map of the Milton Ness area. After Trewin (1987c).
(Figure 3.19) Log of the section at Milton Ness. (a) After Trewin (1987c); (b), idealized calcrete profile after Balin (2000).
(Figure 3.20) Locations of Aberlemno, Tillywhandland and Turin Hill quarries
(Figure 3.21) Section of Aberlemno Quarry. Based on Dineley (1999c) and Armstrong et al. (1978b).
(Figure 3.22) Aberlemno Quarry. Strike section in flaggy sandstones of the Dundee Flagstone Formation. (Photo: C.J. Cleal.)
(Figure 3.23) Location of Tillywhandland Quarry, Angus.
(Figure 3.24) Part of Tillywhandland Quarry, showing lacustrine laminites. (Photo: M.A.E. Browne.)
(Figure 3.25) Section of Tillywhandland Quarry. Based on Trewin and Davidson (1996) and Dineley and Metcalf (1999).
(Figure 3.26) Geological sketch map of the bedrock geology of the area around Whiting Ness.
(Figure 3.27) Conglomerates of the Burnside Sandstone Formation (Upper Old Red Sandstone) resting unconformably on the Arbroath Sandstone Member (Scone Sandstone Formation; Lower Old Red Sandstone) [NO 660 412]. Note the steep angle of the unconformity. (Photo: BGS No. D2730, reproduced with the permission of the Director, British Geological Survey, NERC.)
(Figure 3.28) Geological sketch map of the area around the Tay Bank section and log of the Campsie Limestone Member exposed. After Armstrong et al. (1985).
(Figure 3.29) The Stanley Limestone, a mature fossil soil carbonate (calcrete), exposed at the Tay Bank section. (Photo: M.A.E. Browne.)
(Figure 3.30) Geological map of the Glen Vale area showing limits of the potential GCR site.
(Figure 3.31) Dow Craig in the Knox Pulpit Sandstone Formation. (Photo: J.I. Chisholm.)
(Figure 3.32) Geological map of the area around Wolf's Hole Quarry. After British Geological Survey 1:10 560 Sheet NS 79NE (1976).
(Figure 3.33) Wolf's Hole Quarry. A lava flow at the top of the section rests on thick-bedded sandstones. (Photo: M.A.E. Browne.)
(Figure 3.34) Location and geology of Auchensail Quarry. After British Geological Survey 1:10 560 manuscript map NS 37NW (1984).
(Figure 3.35) Sketch of Auchensail Quarry and its facies associations. After Scott et al. (1976), reproduced by Cleal and Thomas (1995).
(Figure 3.36) Auchensail Quarry: sandstones, siltstones and mudstones of the Teith Sandstone Formation. Note the igneous dyke just to the left of centre of the quarry. (Photo: C.J. Cleal.)
(Figure 3.37) Geological map of the area around Siccar Point, from Cove Harbour to Hirst Rocks. After British Geological Survey 1:50 000 Sheet 34 (Scotland), Eyemouth (1982).
(Figure 3.38) Geological map of Siccar Point: Hutton's Unconformity. After Greig (1988).
(Figure 3.39) Hutton's Unconformity at Siccar Point. (Photo: BGS No. D1471, reproduced with the permission of the Director, British Geological Survey, © NERC.)
(Figure 3.40) Interbedded fluvial and aeolian sandstones at Red Rock, Pease Bay. The aeolian sandstones show sandflow and wind ripple lamination, the fluvial sandstones are sheet-flood deposits (Photo: B.P.J. Williams).
(Figure 3.41) Geological sketch map of the Largs coast section and summary graphic log. The inset shows the location of Largs, Ayrshire. After Bluck (1980b).
(Figure 3.42) Cross-bedded sandstones, west of Knock Castle [NS 1913 6303]. An upward-coarsening unit interfingering between coarse sediment (e) and fine sediment (d) at (a); gradational contact between coarse and fine sediment at (b); sharp, erosive contact at (c), and counter-current ripples at (d); scale rule 1 m. (Photo: Bluck.).
(Figure 3.43) (a) Flow around lateral bar; and (b) mid-channel bar; (c) cross-section through a bar. After Bluck (1992).
(Figure 3.44) Plan and cross-sectional views (A-B) of the interpreted development of bars at Locality 2, WNW of Quarter. Stage 1 records the growth of a linguoid mid-channel bar, Stage 2 records the development into a lateral and chute bar. After Bluck (1980b).
(Figure 3.45) Geological map of the area of North Newton Shore and Hutton's Unconformity, Isle of Arran. Inset shows location of map.
(Figure 3.46) Hutton's Unconformity. Steeply dipping Dalradian metasedimentary rock in the foreground (lower half of image), overlain by more gently inclined thicker-bedded Upper Old Red Sandstone sedimentary rocks dipping towards the sea. (Photo: S.L.B. Arkley.)
(Figure 3.47) Sketches of Hutton's Unconformity at North Newton Shore from Tomkeieff (1953) showing his re-interpretation of the precise contact between the two rock formations. Height of illustrated exposure is about 1 m. (a) — position of plane of unconformity as placed by Hutton (P1); (b) — new position as suggested by Tomkeieff (P2).
(Figure 4.1) Distribution of Old Red Sandstone strata of the Southern Uplands and the Lake District.
(Figure 4.2) Engraving after a drawing of the unconformity at Jedburgh [NT 652 198] by John Clerk of Eldin (1787), used for Plate III of the Theory of the Earth, Volume 1, by James Hutton (1795). Vertical Silurian greywackes and shales are unconformably overlain by Upper Old Red Sandstone basal breccia and overlying sandstones. From Craig et al. (1978), reproduced by permission of Sir R.M. Clerk Bt.
(Figure 4.3) Geological map of the area around Palmers Hill Rail Cutting.
(Figure 4.4) Graphic logs of the Kinnesswood Formation of Liddesdale showing the distribution of calcrete. After Leeder (1976).
(Figure 4.5) Geological map of the Mell Fells–Ullswater area. After British Geological Survey 1:50 000 Sheet 30 (England and Wales), Appleby (2003).
(Figure 4.6) Conglomerate of the Mell Fell Conglomerate Formation on the shore of Ullswater near Pooley Bridge. (Photo: D. Stephenson.)
(Figure 5.1) Correlation of the successions and biostratigraphical classifications of the Old Red Sandstone in the Anglo-Welsh Basin. Ages in millions of years ago (Ma) are from Williams et al. (2000). Broken lines denote imprecisely located boundaries.
(Figure 5.2) Map of the Old Red Sandstone outcrops in the Anglo-Welsh Basin showing location of the GCR sites described in this chapter. After British Geological Survey 1:625 000 Solid Geology Map UK South Sheet, 4th edn (2001).
(Figure 5.3) Palaeogeographical evolution of the Anglo-Welsh Basin. (a) Earliest Přídolí; (b) mid-Přídolí; (c) Lochkovian; (d) late Pragian–early Emsian; (e) Givetian; (f) Frasnian–early Famennian. (a) and (b) after Bassett et al. (1992); (c)–(t) after Bluck et al. (1992).
(Figure 5.4) Geology of the Porth-y-Mor GCR site, Anglesey. Map (a) shows location of Map (b). Map (b) shows the main outcrop of Old Red Sandstone in Anglesey and location of Map (c). Map (c) shows the geology of the Porth-y-Mor site. Maps (b) and (c) after Allen (1965a).
(Figure 5.5) Graphic log of section of coastal exposures between Traeth Dulas and Traeth Lligwy measured by Allen (1965a). The Traeth Bach Formation is from 0 m to 129.54 m (425 feet), the Porth-y-Mor Formation is from 129.54 m to 477.01 m (1565 feet) and the Traeth Lligwy Formation is from 477.01 m to 498.96 m (1637 feet). Thicknesses above the base of the section are shown in metres. The numbers in bold are Allen's cycle numbers in the Porth-y-Mor Formation. After Allen (1965a).
(Figure 5.6) Epsilon cross-bedding in Cycle 42 (see (Figure 5.5)) of the Porth-y-Mor Formation [SH 4940 8780]. Hammer for scale (circled). (Photo: J.R. Davies.)
(Figure 5.7) Geological map of Devil's Hole GCR site. Based on British Geological Survey 1:10 560 manuscript map Shropshire 58NW (1960) and 1:10 000 manuscript map SO 69SE (2002).
(Figure 5.8) Vertical section of the strata at Devil's Hole. Based on Dineley (1999f, fig. 4.8), after M.A. Rowlands (MS).
(Figure 5.9) Geological map of Oak Dingle, Tugford. After British Geological Survey 1:10 560 manuscript map Shropshire 65NW (1960)
(Figure 5.10) Vertical section of the strata in Oak Dingle, Tugford, showing the sedimentary facies and their interpretation by Allen (1964a). After Dineley (19991, fig. 4.11).
(Figure 5.11) Geological map showing location of The Scar GCR site. After British Geological Survey 1:50 000 Sheet 197 (England and Wales), Hay-on-Wye (in press).
(Figure 5.12) Sandstone overlying mudstone at the base of The Scar. (Photo: WJ. Barclay.)
(Figure 5.13) Geological map of Cusop Dingle. Based on British Geological Survey 1:50 000 Sheet 214 (England and Wales), Talgarth (2004).
(Figure 5.14) Graphic log of the section in Cusop Dingle.
(Figure 5.15) Distributary channel sandstone body in the Raglan Mudstone Formation at Cusop Mill fall [SO 239 413]. Fining-upward tabular and trough-cross-stratified beds overlie a scoured surface cut in parallel-bedded fine-grained sandstones that conformably overlie siltstones. The coarser sandstones are more resistant and cap a waterfall. (Photo: D.J. Hawley.)
(Figure 5.16) Geology of the upper part of the Sawdde Gorge: (a) — geological sketch map (north-west part after Derek J. Siveter, 2000); (b) — lithostratigraphical classification of the succession.
(Figure 5.17) Graphic logs of parts of the Old Red Sandstone succession in the Mon Sawdde. 1A,1B — continuous section of the Tilestones Formation and basal part (Pont-ar-llechau Member) of the Gwynfe (Raglan Mudstone) Formation [SN 7282 2452]–[SN 7286 2449]; 2 — part of the 'Middle Division'of the Raglan Mudstone Formation [SN 7308 2400]; 3 — part of the 'Middle Division' containing the Townsend Tuff Bed and Pickard Bay Tuff Bed [SN 7325 2385]; 4 — section typical of the 'Upper Division' of the Raglan Mudstone Formation [SN 7330 2381]–[SN 7332 2372]; 5 — section typical of the St Maughans Formation [SN 7340 2364]. After Almond et al. (1993). Note that the logs have different scales.
(Figure 5.18) Section behind the former Three Horse Shoes Inn [SN 7283 2447] exposing the junction of the basal beds (Capel Horeb Member of Almond et al., 1993) of the Tilestones Formation and the underlying topmost beds of the Lower Roman Camp Formation. The hammer marks the junction. (Photo: R.A. Waters.)
(Figure 5.19) Geological map and location of Pantymaes Quarry. After British Geological Survey 1:50 000 Sheet 213 (England and Wales), Brecon (in press).
(Figure 5.20) Main face of Pantymaes Quarry. Lower sandstones are overlain by mudstones with thin sandstone beds at their top. The lower sandstones are 15 m thick. (Photo: D.J. Hawley.)
(Figure 5.21) Main face at Pantymaes Quarry showing the main sedimentary bounding surfaces in the Sandstone Facies Association. After Owen and Hawley (2000).
(Figure 5.22) Arthropod trackways Diplichnites gouldi in Pantymaes Quarry. (Photo: D.J. Hawley.)
(Figure 5.23) Geological sketch map and location of Heol Senni Quarry. After British Geological Survey 1:50 000 Sheet 213 (England and Wales), Brecon (in press).
(Figure 5.24) View looking into the north-west corner of Heol Senni Quarry. (Photo: W.J. Barclay.)
(Figure 5.25) Geological map of the area of Caeras Quarry. After British Geological Survey 1:10 560 Sheet SN 61NW (1973).
(Figure 5.26) Graphic section of part of Caeras Quarry. After Squirrel( and White (1978).
(Figure 5.27) Topmost beds exposed in Caeras Quarry; red mudstone/siltstone with calcrete nodules rests on sandstone. The hammer is 0.3 m in length. (Photo: W.J. Barclay.)
(Figure 5.28) Geological map of the area around Craig-y-Fro Quarry. After British Geological Survey Scale Sheet SN 92SE (1973).
(Figure 5.29) Graphic log and view of Craig-y-Fro Quarry. After Cleal and Thomas (1995, fig. 4.16). Numbers (1), (2), and (3) are three of the main plant beds. (Photo: D. Edwards.)
(Figure 5.30) Geological map of Abercriban Quarries and vicinity. After British Geological Survey 1:10 560 Sheet SO 01SE (1980).
(Figure 5.31) Northern Abercriban quarry (a) composite log from the north and south ends of the quarry showing palaeocurrent directions. After Lovell (1978a,b).Northern Abercriban quarry (b) — view of part of the northern Abercriban quarry showing the basal beds of the Lower Limestone Shale Group and the upper part of Grey Grits Formation; (c) sketch section of lower part of quarry (after Lovell, 1978a,b). (Photo: BGS No. A11993, reproduced with the permission of the Director, British Geological Survey, © NERC.)
(Figure 5.32) Geological map of Afon y Waen potential GCR site. After British Geological Survey 1:10 560 manuscript maps SN 91NE and SN 91SE (both 1973).
(Figure 5.33) Cwar Llwyd, Mon y Waen. The basal bed of the Plateau Beds Formation comprises 3 m of massive quartz pebble conglomerate above 1.5 m of thinly bedded sandstones and siltstones [SO 9720 1730]. (Photo: BGS No. A12010, reproduced with the permission of the Director, British Geological Survey, NERC.)
(Figure 5.34) Vertical section of the strata in the Mon y Waen. Basal 13 m after Hall et al. (1973), upper part after Lovell (1978a).
(Figure 5.35) Geological map of Duffryn Crawnon potential GCR site. Based on British Geological Survey 1:10 560 manuscript map SO 01NE (1973).
(Figure 5.36) Vertical section of the strata at Duffryn Crawnon. After Lovell (1978a,b).
(Figure 5.37) South face of Blaen Duffryn Crawnon [SO 0936 1507]. Sandstones and siltstones fill a channel in the upper part of the Plateau Beds Formation. Brachiopods are present in the channel-fill. (Photo: BGS No. A12015, reproduced with the permission of the Director, British Geological Survey, NERC.)
(Figure 5.38) Geological map of Craig-y-cwm potential GCR site. After British Geological Survey 1:10 560 manuscript map SO 20NE (1984).
(Figure 5.39) Graphic log of strata at Craig-y-cwm. After Barclay (1989).
(Figure 5.40) Cross-bedded pebbly sandstones above calcrete, Craig-y-cwm Formation, Craig-y-cwm. Hammer for scale. (Photo: BGS No. 13449, reproduced with the permission of the Director, British Geological Survey, 0 NERC.)
(Figure 5.41) Location of Ross-on-Wye, Royal Hotel GCR site. After British Geological Survey Ross-on-Wye Special 1:10 000 Sheet (1980).
(Figure 5.42) Graphic logs of the Brownstones Formation at the Ross-on-Wye Royal Hotel GCR site. (a) — vertical section at Point A on (Figure 5.41); (LI) — elevation showing sedimentary structures at Point B on (Figure 5.41). After Allen (1971, 1978a).
(Figure 5.43) Cross-bedded sandstones of the Brownstones Formation at the Ross-on-Wye, Royal Hotel GCR site. (Photo: W.J. Barclay.)
(Figure 5.44) Geological map of the area around Wilderness Quarry. After British Geological Survey 1:10 560 manuscript map Gloucs. 23SE (1956).
(Figure 5.45) Wilderness Quarry. Main face showing major channelized sandstone bodies and intervening thin mudstones: (Photo: R.T. Mogridge.)
(Figure 5.46) Generalized section of the Brownstones Formation at Wilderness Quarry. After Allen (1971).
(Figure 5.47) Geological sketch map of Lydney GCR site (inset) and composite vertical section of the strata exposed. Map after British Geological Survey 1:10 560 manuscript map SO 60SE (1973). Section based on Allen (1978b) and Dineley (1999e, fig. 3.19).
(Figure 5.48) Calcrete profile in the Psammosteus Limestone at Lydney showing pseudo-anticlinal structure. Hammer (circled) for scale. (Photo: P.R. Wilby.)
(Figure 5.49) Location and simplified geology of Albion Sands and Gateholm Island. Based on Williams (1978) and Lane (2000c, fig. 6.20).
(Figure 5.50) Oblique aerial view looking ENE to Albion Sands, the promontory of Horse Neck connecting with Gateholm Island, and Marloes Sands. (Photo: S. Howells.)
(Figure 5.51) Vertical section of the strata at Albion Sands and Gateholm Island. After Williams (1978).
(Figure 5.52) Geological map of Little Castle Head. Based on Allen (1980), Hancock et al. (1982) and Parker et al. (1983).
(Figure 5.53) Oblique aerial view looking north-west to Little Castle Head. The strata are tightly folded and include the Townsend Tuff Bed and Pickard Bay Tuff Bed, which weather to slots and recesses. (Photo: S. Howells.)
(Figure 5.54) Schematic profile of the Townsend Tuff Bed illustrating its main sedimentological features. After Allen and Williams (1981a).
(Figure 5.55) Geological sketch map of the north side of West Angle Bay and log of the Skrinkle Sandstones Group. After Williams et al. (1982).
(Figure 5.56) Strata in West Angle Bay; view looking east [SM 8503 0380]. The beds dip steeply and young southwards (left to right). The Ridgeway Conglomerate Formation is succeeded by the Stackpole Sandstone Member of the Gupton Formation, which in turn is overlain by the basal beds of the Conglomerate Member of the West Angle Formation. (Photo: P.R. Wilby.)
(Figure 5.57) Aerial oblique view of Freshwater West looking south to Great Furzenip headland. Steep, south-dipping beds of the Freshwater West Formation are cut by the Flimston Bay Fault. The Skrinkle Sandstones Group crops out on Great Furzenip. (Photo: S. Howells.)
(Figure 5.58) Geological map of the Pembroke peninsula and location of the potential GCR site at Freshwater West. Locations of GCR Old Red Sandstone sites on the peninsula are also shown. (1 — Albion Sands and Gateholm Island; 2 — Little Castle Head; 3 — West Angle Bay (North); 4 — Freshwater East–Skrinkle Haven.)
(Figure 5.59) Geological map of Freshwater West. Based on Williams (1978), Allen et al. (1981b) and Williams et al. (1982).
(Figure 5.60) Sedimentary log through part of the Conigar Pit Sandstone Member, Freshwater West Formation at Freshwater West. Thicknesses are in metres from the base of the member. Based on Allen et al. (1981b) and Williams et al. (1982).
(Figure 5.61) Sandstones of the Conigar Pit Sandstone Member, Freshwater West, 114 m above the base of the member. The sequence youngs from left to right. Planar cross-bedded sandstone overlies flat-bedded sandstone and is overlain by sandstone/mudstone and massive calcrete. The sandstones are interpreted as sheet-flood deposits. (Photo: B.P.J. Williams.)
(Figure 5.62) Sedimentary log of the Ridgeway Conglomerate Formation at Freshwater West. Based on Williams et al. (1982) and Allen et al. (1981b).
(Figure 5.63) Conglomerate in the Ridgeway Conglomerate Formation, Freshwater West, 73 m above base of the formation. The sequence youngs from left to right. A pronounced pebble fabric is aligned parallel to the foresets of a large-scale cross-stratified bedset. (Photo: B.P.J. Williams.)
(Figure 5.64) Geological map of the Freshwater East–Skrinkle Haven coast section. After British Geological Survey 1:50 000 sheets 244 and 245 (England and Wales), Pembroke and Linney Head (1983).
(Figure 5.65) Geological map of the Manorbier–Skrinkle Haven coast section. After Williams el al. (1982).
(Figure 5.66) Calcrete forming pseudo-anticlinal structure, Moor Cliffs Formation, Presipe. View looking west, near-vertical sequence younging left to right. (Photo: W.J. Barclay.)
(Figure 5.67) Oblique aerial view looking east of Old Castle Head. Vertical strata of the Moor Cliffs Formation. The strata young to the north (right to left) and a Fault displaces them dextrally. Tuffs are marked by slots in the cliffs (RCT — Rook's Cave Tuff; TT — Townsend Tuff Bed; PBT — Pickard Bay Tuff Bed; CPC — Chapel Point Calcretes Member). Other slots probably mark unnamed tuffs. (Photo: S. Howells.)
(Figure 5.68) The Townsend Riff Bed, Old Castle Head. View looking east, sequence younging right to left. (Photo: B.P.J.
(Figure 5.69) Near-vertical basal beds of the Freshwater West Formation. View looking WSW at southern end of Manorbier Bay. The Chapel Point Calcretes Member forms the notch on the left, the sequence younging left to right. (Photo: W.J. Barclay.)
(Figure 5.70) Geological sketch map of the Llansteffan area. After British Geological Survey 1:10 560 manuscript map Carmarthenshire 45SE (1906).
(Figure 5.71) The Chapel Point Calcretes Member, Llansteffan. The topmost calcrete of a stacked succession of calcretes overlies the careously weathered top of the one below. (Photo: W.J. Barclay.)
(Figure 5.72) Vertical section of the strata exposed at Llansteffan. Based on Allen (1978c) and Allen et al. (1981b).
(Figure 5.73) Location and geology of the Portishead GCR site. (a) Geological map (after British Geological Survey 1:50 000 Sheet 264 (England and Wales), Bristol (2003)); (b) detailed map of section in southern Kilkenny Bay (based on Pick (1964a) and Williams and Hancock (1977)). Letters in (b) are 'formations' of Pick (1964a).
(Figure 5.74) Generalized vertical section of the Old Red Sandstone at Portishead, with selected palaeocurrent rose diagrams. The rose diagrams show preferred palaeocurrent directions grouped in 20° classes and plotted as number frequency percent. The circles mark the 20% frequency level. Small arrows show the vector means of the cross-bedding dip azimuths. Based on Pick (1964a) and Williams and Hancock (1977). Letters A, B, etc. are 'formations' of Pick (1964a).
(Figure 5.75) Conglomerates of the Woodhill Bay Conglomerate above sandstones of the Black Nore Sandstone Formation, Kilkenny Bay [ST 4579 7681]. A pipe-like carbonate body extends across the junction and carbonate nodules occur in the Black Nore Sandstone Formation. (Photo: BGS No. A10737, reproduced with the permission of the Director, British Geological Survey, © NERC.)
(Figure 5.76) Geological map of the Glenthorne area, north Devon. Based on British Geological Survey 1:10 560 Sheet SS 74NE (1983) and 1:10 000 manuscript map 84NW (1993).
(Figure 5.77) Summary of the sedimentary facies of the Hangman Sandstone Formation and their interpretation. After Edwards (1999).
(Figure 5.78) Graphic sedimentary log and interpretation of the Hangman Sandstone Formation at Yellow Hammer Rock [SS 7980 4975]. After Edwards (1999).
(Figure 5.79) Sedimentary features of the Hangman Sandstone Formation at Yellow Hammer Rock [SS 7980 4970]. A single-storey channel sandstone with an undulatory erosive base (Facies 1) overlies sharp-based sheet sandstones (Facies 4). The rucksack (circled) is 0.5 m high. (Photo: BGS No. GS480, reproduced with the permission of the Director, British Geological Survey, © NERC.
Tables
(Table 1.1) GCR Old Red Sandstone sites and proposed sites, with main criteria for their selection. Continued on page 7.
(Table 1.2) GCR sites in the Old Red Sandstone described in the fossil fishes GCR volume. After Dineley and Metcalf (1999). Continued on page 9.
(Table 1.3) GCR sites in the Old Red Sandstone described in the Palaeozoic palaeobotany GCR volume. After Cleal and Thomas (1995).
(Table 1.4) GCR sites in the Old Red Sandstone described in the Silurian stratigraphy GCR volume. After Aldridge et al. (2000).
(Table 1.5) GCR sites with Old Red Sandstone sedimentary rocks described in the Caledonian igneous rocks volume. After Stephenson et al. (1999).
References