Southern and eastern parts of the central English county of Warwickshire are underlain by a poorl... more Southern and eastern parts of the central English county of Warwickshire are underlain by a poorly exposed but well-preserved and richly fossiliferous succession of Lower and Middle Jurassic strata. This article outlines the nature of the Jurassic sediments and their palaeoenvironments, and highlights some of the more important sites and discoveries.
Geological Society, London, Special …, Jan 1, 2008
... dug into a degraded face, the roofed structure (approximately 1 m high) protects a section ex... more ... dug into a degraded face, the roofed structure (approximately 1 m high) protects a section exposing the junction of the arenaceous Brandon Member (Baginton ... Earth Heritage 18:67. ↵: O'Halloran D.,; Green C.,; Harley M.,; Stanley M.,; Knill J. Copp CJT. (1994) in Geological and ...
Relatively few foraminiferal taxa have been previously recorded from the Portlandian strata (Uppe... more Relatively few foraminiferal taxa have been previously recorded from the Portlandian strata (Upper Jurassic) of southern England. Sampling of poorly-lithified lithologies in Buckinghamshire has revealed relatively diverse foraminiferal microfaunas, including fifteen new records for southern England. These supplement associated micro- and macrofauna in indicating shallow, well-oxygenated nearshore marine environments.
Proceedings of the Yorkshire Geological …, Jan 1, 2008
Summary The upper part of the Scunthorpe Mudstone Formation (Sinemurian, Lower Jurassic) beneath ... more Summary The upper part of the Scunthorpe Mudstone Formation (Sinemurian, Lower Jurassic) beneath the Frodingham Ironstone at Scunthorpe, north-east England, comprises richly fossiliferous mudrocks and limestones. These strata were recently exposed in ...
SUMMARY A previously undocumented marine reptile fauna comprising well-preserved ichthyosaur and ... more SUMMARY A previously undocumented marine reptile fauna comprising well-preserved ichthyosaur and plesiosaur remains is described from the Early Jurassic Saltford Shale Member within the Blue Lias Formation of central England. Two ichthyosaur genera are recognized, namely Leptonectes and Ichthyosaurus, as well as generically indeterminate remains of plesiosaurs. The specimens include partly-articulated skeletons, reflecting preservation in dysaerobic argillaceous sediment in a dominantly low-energy setting on ...
Grazing bioerosion, notably by chitons, gastropods and regular echinoids, is a powerful destructi... more Grazing bioerosion, notably by chitons, gastropods and regular echinoids, is a powerful destructive force in many recent shallow-marine environments and impacts significantly on sessile epibionts through grazing predation and/or unselective dislodgement. Grazing bioerosion was an important component of a major phase of biotic escalation; the Mesozoic marine revolution. Recent investigations of hard substrates in southern British Jurassic marine formations have identified widespread ichnofossils attributable to grazing activity by gastropods and/or chitons, and regular echinoids. The co-occurring benthic macrofaunas include groups that would have been vulnerable to grazing disturbance and dislodgement; notably articulate brachiopods. The emerging ichnological evidence strengthens the argument for grazing bioerosion as a significant contributor to the Mesozoic–Cenozoic decline of the articulate brachiopods, and their retreat to deep-water and/or cryptic refugia.
Southern British Jurassic strata were deposited in epicontinental, mainly shallow-marine environm... more Southern British Jurassic strata were deposited in epicontinental, mainly shallow-marine environments, influenced by eustatically controlled sea-level fluctuation, regional tectonism and a warm, predominantly humid climatic regime (Hallam, 1975 5. Hallam, A. 1975. ...
Palaeogeography, Palaeoclimatology, Palaeoecology, Jan 1, 2008
Minor bedforms within the mudstone-dominated Early Jurassic Hettangian Saltford Shale Member (Lia... more Minor bedforms within the mudstone-dominated Early Jurassic Hettangian Saltford Shale Member (Liasicus up to Angulata Chronozone) of the Blue Lias Formation in central England, indicate weak seafloor erosion in a mid to outer ramp setting. Distal storm flows below maximum storm wave base are proposed as the most likely generative mechanism for silty scour and gutter casts that enclose concentrations of well-preserved schlotheimiid ammonites and arthropod trace fossils. Within the upper part of the Saltford Shale (probably Angulata Chronozone), a discrete layer of reworked and bioencrusted limestone nodules signifies an episode of more persistent seafloor erosion. The immediately overlying strata, transitional to the Hettangian–Sinemurian Rugby Limestone Member, are relatively bioturbated and feature fossils of macrobenthos, as well as shell concentrations resembling relatively proximal storm beds. This suggests that the reworked nodule horizon marks sea-level fall, rather than stratigraphic condensation associated with sediment starvation. The biostratigraphic evidence raises the possibility that this erosional episode correlates with a mid-Angulata Chronozone hiatus documented from the Wessex Basin, southwest England. Equally however, it could be linked to contemporaneous movement on one or more nearby faults, affecting the southern part of the English East Midlands Shelf.
Proceedings of the Geologists' Association, Jan 1, 2000
Five categories of shelly sediment are documented from the upper part of the alluvial Wessex Form... more Five categories of shelly sediment are documented from the upper part of the alluvial Wessex Formation (Barremian) on the Isle of Wight, southern England. They represent biostratinomic ‘windows’ within an essentially corrosive and intermittently depositional, warm to very hot meanderplain environment. The fauna is dominated by unionoid bivalves with rarer viviparid and physid gastropods. These molluscs are considered to have adopted similar life modes to their present-day freshwater counterparts. Thick, regularly spaced growth lines in some bivalves probably reflect alternating wet and dry phases and solution-pitted shells indicate acidic surface waters on the floodplains. Autochthonous concentrations characterize well-oxygenated pond or lake deposits and consist of Margaritifera preserved in their inferred life position. Such water bodies were subjected to wet-period sediment influx and disturbance and to dry-period desiccation. Poorly sorted muddy conglomerates representing allochthonous mudflow sediments contain closed, variably oriented unionoids, indicating their catastrophic exhumation and subsequent rapid burial during periodic floods. Channel sediments are poorly fossiliferous. Sand bodies containing viviparid gastropods are possibly crevasse splay deposits.
Derived fossils occur in all the principal facies associations of the southern English Wealden su... more Derived fossils occur in all the principal facies associations of the southern English Wealden succession (non-marine early Cretaceous). They confirm the presence of Palaeozoic and early–mid Mesozoic source massifs surrounding the Weald and Wessex depocentres, fringed by scarps and intrabasinal highs of Jurassic strata. The derived macrofossil material is largely siliceous and phosphatic. It gains abundance in lake strandline gravels but also occurs as scattered reptilian gastroliths and among lagoonal shell concentrations. Calcareous fossils are abundant at one site, reflecting proximity to source. Jurassic dinoflagellate cysts are widespread among finer-grained facies.
Proceedings of the Geologists' Association, Jan 1, 1998
A stratigraphie section of the Vectis Formation (Wealden Group, Lower Cretaceous) at Compton Bay,... more A stratigraphie section of the Vectis Formation (Wealden Group, Lower Cretaceous) at Compton Bay, Isle of Wight is presented, including lithological and palaeontological data. The sequence is relatively thin, indicating either attenuation towards the faulted northern margin of the Wessex sub-basin or proximity to an active growth fault associated with this structure. The succession is closely comparable to the Atherfield ‘type’ section in terms of lithofacies and fauna, enabling recognition of intrabasinal marker horizons. The salinity tolerances of molluscan fossils from the section are discussed and storm-generated bioclastic marker beds are figured.
Proceedings of the Geologists' Association, Jan 1, 2012
The Wealden strata (non-marine Lower Cretaceous) of the Weald Sub-basin outcrop in the Weald dist... more The Wealden strata (non-marine Lower Cretaceous) of the Weald Sub-basin outcrop in the Weald district of south-east England; the Wealden type-area. The succession is made up of the mixed alluvial–lacustrine–lagoonal Hastings Beds Group below and the predominantly lacustrine–lagoonal Weald Clay Group above. Deposition was strongly influenced by tectonism amongst surrounding massifs, and the warm to hot, periodically wet Wealden climate. Geological Conservation Review sites within the Weald district are dominated by inland sites, but also include extensive coastal cliff and foreshore exposures near Hastings, East Sussex. The Wealden strata have been documented and interpreted since the earliest days of geological enquiry in Great Britain. Collectively, the selected sites demonstrate the key elements of a depositional model for the Wealden of the Weald, developed and published by Professor Percival Allen FRS (1917–2008) in these Proceedings (Allen, 1975). The sites are documented and interpreted, with special reference to research history, chronostratigraphy, structural context, palaeoenvironments, palaeobiology and palaeoclimatology. New directions for research are proposed, as applicable.
Proceedings of the Geologists' Association, Jan 1, 2012
Geological Conservation Review sites representing the non-marine Lower Cretaceous Wealden strata ... more Geological Conservation Review sites representing the non-marine Lower Cretaceous Wealden strata provide field evidence for the physical and biological development of what is now southern England, between approximately 120 and 135 million years ago. Knowledge of Wealden climates, palaeogeology, landscapes, hydrology and palaeobiology is synthesized and summarised, with reference to the Weald and Wessex sub-basins.
Proceedings of the Geologists' Association, Jan 1, 2011
Non-marine Lower Cretaceous beds of Wealden aspect have long been known from the northern margin ... more Non-marine Lower Cretaceous beds of Wealden aspect have long been known from the northern margin of the Wessex–Weald Basin, between Wiltshire and the south Midlands. Termed the Whitchurch Sands Formation, these badly exposed and generally poorly fossiliferous strata appear to represent interdigitating alluvial and brackish-marine units separated by significant sedimentary breaks. Geological Conservation Review sites within the Whitchurch Sands are described and interpreted for their chronostratigraphic, palaeoenvironmental and palaeoclimatic significance.
Proceedings of the Geologists' Association, Jan 1, 2011
This paper summarises the author's research association with Percival (‘Perce’) Allen FRS (1917–2... more This paper summarises the author's research association with Percival (‘Perce’) Allen FRS (1917–2008), whose wide-ranging and seminal contributions to Wealden (non-marine Lower Cretaceous) sedimentological and palaeoenvironmental interpretation spanned seven decades. The Geological Conservation Review (GCR) Special Issue on the Wealden was initiated as a collaborative research programme initiated during the late 1990s. Stemming from this, the GCR accounts are seen very much as the summation of Perce Allen's lifelong Wealden studies, as demonstrated by GCR sites throughout southern England.
Southern and eastern parts of the central English county of Warwickshire are underlain by a poorl... more Southern and eastern parts of the central English county of Warwickshire are underlain by a poorly exposed but well-preserved and richly fossiliferous succession of Lower and Middle Jurassic strata. This article outlines the nature of the Jurassic sediments and their palaeoenvironments, and highlights some of the more important sites and discoveries.
Geological Society, London, Special …, Jan 1, 2008
... dug into a degraded face, the roofed structure (approximately 1 m high) protects a section ex... more ... dug into a degraded face, the roofed structure (approximately 1 m high) protects a section exposing the junction of the arenaceous Brandon Member (Baginton ... Earth Heritage 18:67. ↵: O'Halloran D.,; Green C.,; Harley M.,; Stanley M.,; Knill J. Copp CJT. (1994) in Geological and ...
Relatively few foraminiferal taxa have been previously recorded from the Portlandian strata (Uppe... more Relatively few foraminiferal taxa have been previously recorded from the Portlandian strata (Upper Jurassic) of southern England. Sampling of poorly-lithified lithologies in Buckinghamshire has revealed relatively diverse foraminiferal microfaunas, including fifteen new records for southern England. These supplement associated micro- and macrofauna in indicating shallow, well-oxygenated nearshore marine environments.
Proceedings of the Yorkshire Geological …, Jan 1, 2008
Summary The upper part of the Scunthorpe Mudstone Formation (Sinemurian, Lower Jurassic) beneath ... more Summary The upper part of the Scunthorpe Mudstone Formation (Sinemurian, Lower Jurassic) beneath the Frodingham Ironstone at Scunthorpe, north-east England, comprises richly fossiliferous mudrocks and limestones. These strata were recently exposed in ...
SUMMARY A previously undocumented marine reptile fauna comprising well-preserved ichthyosaur and ... more SUMMARY A previously undocumented marine reptile fauna comprising well-preserved ichthyosaur and plesiosaur remains is described from the Early Jurassic Saltford Shale Member within the Blue Lias Formation of central England. Two ichthyosaur genera are recognized, namely Leptonectes and Ichthyosaurus, as well as generically indeterminate remains of plesiosaurs. The specimens include partly-articulated skeletons, reflecting preservation in dysaerobic argillaceous sediment in a dominantly low-energy setting on ...
Grazing bioerosion, notably by chitons, gastropods and regular echinoids, is a powerful destructi... more Grazing bioerosion, notably by chitons, gastropods and regular echinoids, is a powerful destructive force in many recent shallow-marine environments and impacts significantly on sessile epibionts through grazing predation and/or unselective dislodgement. Grazing bioerosion was an important component of a major phase of biotic escalation; the Mesozoic marine revolution. Recent investigations of hard substrates in southern British Jurassic marine formations have identified widespread ichnofossils attributable to grazing activity by gastropods and/or chitons, and regular echinoids. The co-occurring benthic macrofaunas include groups that would have been vulnerable to grazing disturbance and dislodgement; notably articulate brachiopods. The emerging ichnological evidence strengthens the argument for grazing bioerosion as a significant contributor to the Mesozoic–Cenozoic decline of the articulate brachiopods, and their retreat to deep-water and/or cryptic refugia.
Southern British Jurassic strata were deposited in epicontinental, mainly shallow-marine environm... more Southern British Jurassic strata were deposited in epicontinental, mainly shallow-marine environments, influenced by eustatically controlled sea-level fluctuation, regional tectonism and a warm, predominantly humid climatic regime (Hallam, 1975 5. Hallam, A. 1975. ...
Palaeogeography, Palaeoclimatology, Palaeoecology, Jan 1, 2008
Minor bedforms within the mudstone-dominated Early Jurassic Hettangian Saltford Shale Member (Lia... more Minor bedforms within the mudstone-dominated Early Jurassic Hettangian Saltford Shale Member (Liasicus up to Angulata Chronozone) of the Blue Lias Formation in central England, indicate weak seafloor erosion in a mid to outer ramp setting. Distal storm flows below maximum storm wave base are proposed as the most likely generative mechanism for silty scour and gutter casts that enclose concentrations of well-preserved schlotheimiid ammonites and arthropod trace fossils. Within the upper part of the Saltford Shale (probably Angulata Chronozone), a discrete layer of reworked and bioencrusted limestone nodules signifies an episode of more persistent seafloor erosion. The immediately overlying strata, transitional to the Hettangian–Sinemurian Rugby Limestone Member, are relatively bioturbated and feature fossils of macrobenthos, as well as shell concentrations resembling relatively proximal storm beds. This suggests that the reworked nodule horizon marks sea-level fall, rather than stratigraphic condensation associated with sediment starvation. The biostratigraphic evidence raises the possibility that this erosional episode correlates with a mid-Angulata Chronozone hiatus documented from the Wessex Basin, southwest England. Equally however, it could be linked to contemporaneous movement on one or more nearby faults, affecting the southern part of the English East Midlands Shelf.
Proceedings of the Geologists' Association, Jan 1, 2000
Five categories of shelly sediment are documented from the upper part of the alluvial Wessex Form... more Five categories of shelly sediment are documented from the upper part of the alluvial Wessex Formation (Barremian) on the Isle of Wight, southern England. They represent biostratinomic ‘windows’ within an essentially corrosive and intermittently depositional, warm to very hot meanderplain environment. The fauna is dominated by unionoid bivalves with rarer viviparid and physid gastropods. These molluscs are considered to have adopted similar life modes to their present-day freshwater counterparts. Thick, regularly spaced growth lines in some bivalves probably reflect alternating wet and dry phases and solution-pitted shells indicate acidic surface waters on the floodplains. Autochthonous concentrations characterize well-oxygenated pond or lake deposits and consist of Margaritifera preserved in their inferred life position. Such water bodies were subjected to wet-period sediment influx and disturbance and to dry-period desiccation. Poorly sorted muddy conglomerates representing allochthonous mudflow sediments contain closed, variably oriented unionoids, indicating their catastrophic exhumation and subsequent rapid burial during periodic floods. Channel sediments are poorly fossiliferous. Sand bodies containing viviparid gastropods are possibly crevasse splay deposits.
Derived fossils occur in all the principal facies associations of the southern English Wealden su... more Derived fossils occur in all the principal facies associations of the southern English Wealden succession (non-marine early Cretaceous). They confirm the presence of Palaeozoic and early–mid Mesozoic source massifs surrounding the Weald and Wessex depocentres, fringed by scarps and intrabasinal highs of Jurassic strata. The derived macrofossil material is largely siliceous and phosphatic. It gains abundance in lake strandline gravels but also occurs as scattered reptilian gastroliths and among lagoonal shell concentrations. Calcareous fossils are abundant at one site, reflecting proximity to source. Jurassic dinoflagellate cysts are widespread among finer-grained facies.
Proceedings of the Geologists' Association, Jan 1, 1998
A stratigraphie section of the Vectis Formation (Wealden Group, Lower Cretaceous) at Compton Bay,... more A stratigraphie section of the Vectis Formation (Wealden Group, Lower Cretaceous) at Compton Bay, Isle of Wight is presented, including lithological and palaeontological data. The sequence is relatively thin, indicating either attenuation towards the faulted northern margin of the Wessex sub-basin or proximity to an active growth fault associated with this structure. The succession is closely comparable to the Atherfield ‘type’ section in terms of lithofacies and fauna, enabling recognition of intrabasinal marker horizons. The salinity tolerances of molluscan fossils from the section are discussed and storm-generated bioclastic marker beds are figured.
Proceedings of the Geologists' Association, Jan 1, 2012
The Wealden strata (non-marine Lower Cretaceous) of the Weald Sub-basin outcrop in the Weald dist... more The Wealden strata (non-marine Lower Cretaceous) of the Weald Sub-basin outcrop in the Weald district of south-east England; the Wealden type-area. The succession is made up of the mixed alluvial–lacustrine–lagoonal Hastings Beds Group below and the predominantly lacustrine–lagoonal Weald Clay Group above. Deposition was strongly influenced by tectonism amongst surrounding massifs, and the warm to hot, periodically wet Wealden climate. Geological Conservation Review sites within the Weald district are dominated by inland sites, but also include extensive coastal cliff and foreshore exposures near Hastings, East Sussex. The Wealden strata have been documented and interpreted since the earliest days of geological enquiry in Great Britain. Collectively, the selected sites demonstrate the key elements of a depositional model for the Wealden of the Weald, developed and published by Professor Percival Allen FRS (1917–2008) in these Proceedings (Allen, 1975). The sites are documented and interpreted, with special reference to research history, chronostratigraphy, structural context, palaeoenvironments, palaeobiology and palaeoclimatology. New directions for research are proposed, as applicable.
Proceedings of the Geologists' Association, Jan 1, 2012
Geological Conservation Review sites representing the non-marine Lower Cretaceous Wealden strata ... more Geological Conservation Review sites representing the non-marine Lower Cretaceous Wealden strata provide field evidence for the physical and biological development of what is now southern England, between approximately 120 and 135 million years ago. Knowledge of Wealden climates, palaeogeology, landscapes, hydrology and palaeobiology is synthesized and summarised, with reference to the Weald and Wessex sub-basins.
Proceedings of the Geologists' Association, Jan 1, 2011
Non-marine Lower Cretaceous beds of Wealden aspect have long been known from the northern margin ... more Non-marine Lower Cretaceous beds of Wealden aspect have long been known from the northern margin of the Wessex–Weald Basin, between Wiltshire and the south Midlands. Termed the Whitchurch Sands Formation, these badly exposed and generally poorly fossiliferous strata appear to represent interdigitating alluvial and brackish-marine units separated by significant sedimentary breaks. Geological Conservation Review sites within the Whitchurch Sands are described and interpreted for their chronostratigraphic, palaeoenvironmental and palaeoclimatic significance.
Proceedings of the Geologists' Association, Jan 1, 2011
This paper summarises the author's research association with Percival (‘Perce’) Allen FRS (1917–2... more This paper summarises the author's research association with Percival (‘Perce’) Allen FRS (1917–2008), whose wide-ranging and seminal contributions to Wealden (non-marine Lower Cretaceous) sedimentological and palaeoenvironmental interpretation spanned seven decades. The Geological Conservation Review (GCR) Special Issue on the Wealden was initiated as a collaborative research programme initiated during the late 1990s. Stemming from this, the GCR accounts are seen very much as the summation of Perce Allen's lifelong Wealden studies, as demonstrated by GCR sites throughout southern England.
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