Lower Greensand Research Articles

A marine microvertebrate fauna from a temporary exposure of the Atherfield Clay Formation, Reigate, Surrey

A temporary exposure of the nearshore marine Atherfield Clay (Lower Greensand Formation, Aptian, Early Cretaceous) in the Reigate area (Wonham Mill) of Surrey was sampled for microvertebrate remains in Autumn 2013. Samples amounting to 858 kg of sediment were washed, dried, and sieved to 0.325 mm and the residue searched for all fossil content. This is the first definitive study of the Atherfield Clay chondrichthyan fauna of Surrey. The samples yielded teeth of hybodont sharks (Planohybodus ensis, Lonchidion breve), neoselachian sharks (Heterodontus sulcatus, Cretascyllium hassei, Protospinax sp., Protolamna sokolovi, Lamnid indet., Scyliorhinus muelleri, Scyliorhinus gen. et sp. indet., Protoscyliorhinus sp.) and batoids (Belemnobatis picteti, Squatirhina sp.). The neoselachian sharks and rays all constitute the first confident records for the various genera in the Atherfield Clay of the United Kingdom. Dermal denticles and bony fish teeth are also present in the samples, which also yielded small numbers of invertebrates (ammonite and crustacean), microcoprolites (Tomaculopsis tomaculopsis) and plant remains (fern indusia). The state of preservation of the chondrichthyan material suggests that none of the specimens are derived from older strata; the fauna is indigenous. The Surrey Atherfield Clay fauna is distinct from that recorded from the Atherfield Bone Bed on the Isle of Wight and the roughly coeval boreal fauna of the Speeton Clay.

Evidence-based requirements for perceptualising intercatchment groundwater flow in hydrological models

Abstract. Groundwater-dominated catchments are often critical for nationally important water resources. Many conceptual rainfall–runoff models tend to degrade in their model performance in groundwater-dominated catchments, as they are rarely designed to simulate spatial groundwater behaviours or interactions with surface waters. Intercatchment groundwater flow is one such neglected variable. Efforts have been made to incorporate this process into existing models, but there is a need for improving our perceptual models of groundwater–surface water interactions prior to any model modifications. In this study, national meteorological, hydrological, hydrogeological, geological and artificial influence (characterising abstractions and return flows) datasets are used to infer a perceptual model of intercatchment groundwater flow (IGF) and how it varies across the river Thames, United Kingdom (UK). We characterise the water balance, presence of gaining/losing river reaches and intra-annual dynamics in 80 subcatchments of the river Thames, taking advantage of its wealth of data, densely gauged river network and geological variability. We show the prevalence of non-conservative river reaches across the study area, with heterogeneity both between, and within, geological units, giving rise to a complex distribution of recharge and discharge points along the river network. We infer where non-conservative reaches can be attributed to IGF and where other processes (e.g. surface water abstractions) are the likely cause. Through analysis of recorded reach length water balance data and hydrogeological perceptualisation, we conclude that outcrops of carbonate fractured aquifers (Chalk and Jurassic limestone) show evidence of IGF both from headwater to downstream reaches, and out-of-catchment via spring lines. We found variability across the study area, with more seasonality and variability in river catchments on Jurassic limestone outcrops compared to Chalk and Lower Greensand outcrops. Our results demonstrate the need for local investigation and hydrogeological perceptualisation within regional analysis, which we show to be achievable given relatively simple geological interpretation and data requirements. We support the inclusion of IGF fluxes within existing models to enable calibration improvements in groundwater-dominated catchments, but with geologically specific characteristics, and (when perceptually appropriate) connectivity between catchments.

Using environmental tracers to evaluate the preservation of palaeoclimate signals in aquifers of the London Basin, UK

The concept of aquifer basins as palaeoclimate archives has existed for some decades, yet few detailed studies comparing aquifer types have been carried out. To assess the potential of a particular aquifer as an archive, its hydrogeochemical characteristics must be thoroughly investigated, ideally in comparison to an adjacent aquifer which can be shown to substantially preserve its ice-age endowment at depth. The London Basin (UK) presents such an opportunity, containing two main aquifers of contrasting type: the Chalk, a fractured microporous limestone, and the Lower Greensand, a porous sandstone. Despite intensive exploitation of both, evidence for Devensian (late-glacial) water remains at depth, though this differs between aquifer type. To understand the reasons for this, a suite of environmental tracers has been applied. In addition to hydrochemistry, stable isotopes (δ18O, δ2H), carbon isotopes (δ13C-DIC, 14C-DIC) and noble gases (He, Ne, Ar, Kr and Xe), two tracers new to the basin (CFCs and 14C-DOC) have been used. In effect the Lower Greensand appears to be the ‘reference aquifer’, preserving recharge from prior to the Last Glacial Maximum (LGM), while the Chalk contains mixed water, with no remaining trace of the undiluted pre-LGM end member even at depth in remote parts of the confined basin. Whereas both aquifers had in the past given maximum 14C-DIC model ages ≥ 30kyr (the effective limit of that method), in the present study the use of 14C-DOC has reduced this to 23.4 kyr (Lower Greensand) and 17.2 kyr (Chalk). Similar contrasts in maximum stable isotope depletions (−8.2 ‰ and −7.8 ‰ δ18O) and noble-gas-derived recharge temperature minima (2.6° and 4.1 °C) were also observed. CFCs were found at all Chalk sites, with traces detectable even at 40 km from outcrop, so some climate signal degradation appears inevitable throughout the Chalk aquifer of the basin. A correlation between 14C activity and excess 4He suggests that deep saline water in the Lower Greensand could be ≥ 50kyr old. The use of 14C-DOC in particular appears to be key to understanding how reliable these individual aquifers are as palaeoarchives.

The heteromorph ammonite Tropaeum (Tropaeum) evolutum sp. nov. from the Hythe Formation, Lower Greensand Group (basal upper Aptian, Lower Cretaceous) of Maidstone, Kent, UK

Tropaeum is a genus of large to very large heteromorph ammonites, typical of the Aptian and among the dominant invertebrate organisms of its time. Here we describe a new species, Tropaeum (Tropaeum) evolutum sp. nov., from the basal upper Aptian Epicheloniceras martinioides Zone of the now back-filled Coombe Quarry at Maidstone, Kent, southern England. The new species is characterised by remarkably evolute coiling, the umbilical diameter exceeding 56% of the total, and by a body-chamber of rather more than half a whorl, which is boldly sculpted throughout with fourteen widely, but equally spaced single primaries. Unlike many early (lower Aptian) Tropaeum species, where the adult body-chamber is uncoiled, it appears that in the upper Aptian T. (T.) evolutum sp. nov., the whorls remained just in contact to the end. This follows the general trend exhibited by other late examples of the genus.

Hydrogeochemical indications of regional flow in the Lower Greensand aquifer of the London Basin

The Lower Greensand (LGS) forms the second most important aquifer in the London Basin but, being largely absent beneath the city itself, has received much less attention than the ubiquitous overlying Chalk aquifer. While the general directions of groundwater flow in the Chalk are well established, there has been much less certainty about flow in the LGS owing to regionally sparse borehole information. This study focuses on two hitherto uncertain aspects of the confined aquifer: the sources of recharge to the west-central London Basin around Slough, and the fate of LGS water where the aquifer thins out on the flank of the London Platform in the Gravesend–Medway–Sheppey area on the southern side of the basin. The application of hydrogeochemical techniques including environmental isotopes indicates that recharge to the Slough area is derived from the northern LGS outcrop, probably supplemented by downward leakage from the Chalk, while upward leakage from the LGS in north Kent is mixing with Chalk water to the extent that some Chalk boreholes on the Isle of Sheppey are abstracting high proportions of water with an LGS fingerprint. In doing so, this study demonstrates the value of re-examining previously published data from a fresh perspective. Thematic collection: This article is part of the Hydrogeology of Sandstone collection available at: https://www.lyellcollection.org/cc/hydrogeology-of-sandstone

Dinosaur material from the Lower Greensand Group of Upware, Cambridgeshire, and the age of ‘Wealden’ vertebrates from the ‘Bedfordshire Straits’

Post-Wealden dinosaur remains are rare in the UK, so any material from late Early or Late Cretaceous deposits is potentially of palaeoecological and palaeobiogeographical significance. Four dinosaur specimens collected from the Woburn Sands Formation (Aptian) of Upware, Cambridgeshire were described briefly by Walter Keeping in 1883, but have not been reappraised since. These specimens are identified herein as a ?turiasaurian sauropod tooth and indeterminate iguanodontian ornithopod remains (a tooth, middle caudal vertebra, pollex ungual). Although collected from the Woburn Sands Formation, it is likely that all of these fossils were reworked from older (now absent) sediments and they have usually been regarded as either ‘Wealden’ or Neocomian in age, presumably due to previous identifications of some of these specimens as Iguanodon. However, consideration of UK dinosaur faunas and regional geology indicates that these fossils could potentially be older. Further work is needed on the derived terrestrial fossils of the Lower Greensand Group in order to constrain their ages more precisely so that they can be incorporated into broader studies of regional diversity and palaeoecology.

The youngest dinosaur footprints from England and their palaeoenvironmental implications

Newly discovered dinosaur footprints from the Lower Cretaceous (Albian) Folkestone Formation (Lower Greensand Group) of Kent in S.E. England can be referred to theropod, ornithopod and possibly ankylosaur dinosaurs. The occurrence of dinosaur footprints, together with fossil wood and oysters in a matrix of well-rounded quartz grains indicates a coastal depositional environment of an extremely shallow depth, perhaps with short periods of subaerial exposure. This is the first record of dinosaur footprints from the Folkestone Formation, and it represents the youngest association of dinosaur footprints from England. The moderately diverse dinosaur ichnoassemblage of theropods, ornithopods, ankylosaurs and previously documented fossils indicate deposition on a sandy beach setting.

A highly pneumatic middle Cretaceous theropod from the British Lower Greensand

AbstractA series of axial elements from the Aptian Ferruginous Sands Formation of the Lower Greensand Group, discovered on the foreshore near Knock Cliff on the Isle of Wight, UK are (bar some isolated teeth and fragmentary postcranial material from the Cenomanian Cambridge Greensand) the youngest non‐avian theropod remains reported from the British Mesozoic. These specimens have the potential to shed light on a poorly known section of the European dinosaur record. Consistency in size, appearance and adhering matrix indicates that the vertebrae belong to the same individual. This was a mid‐sized tetanuran, the presence of several diagnostic characters indicating that it should be recognized as a new taxon, herein named Vectaerovenator inopinatus. The cervical and dorsal vertebrae are camerate and highly pneumatic. Tetanuran features include opisthocoelous cervicals and pneumatic foramina located within fossae; however, assigning this specimen to a specific clade is problematic. Within Tetanurae, Vectaerovenator possesses axial structures and homoplastic features seen in megalosauroids, carcharodontosaurians and certain coelurosaurs. Not only is Vectaerovenator one of the UK's youngest non‐bird dinosaurs, and one of few valid British Greensand taxa, it is also the first diagnosable theropod taxon to be named from Aptian deposits of Europe.

The ‘coprolite’ bearing Woburn Sands Formation, Lower Greensand Group (Aptian) at Upware, Cambridgeshire, UK

Upware, about 15 km north of Cambridge, eastern England, was heavily involved in the ‘Coprolite’ Industry during the 19th century. Rich phosphate deposits especially at the base of the Lower Greensand (Early Cretaceous) were dug by hand and after processing supplied the Victorian agricultural industry with fertiliser. They were also a source of abundant reworked and indigenous fossils which feature in the original accounts and descriptions of the geology and palaeontology of the area including those in the classic award-winning Sedgwick Prize essays of Harris Teall in 1873 and Walter Keeping in 1879. Today, however, there are no permanent exposures of the Lower Greensand in the area. The sites of the original commercial excavations have been returned to agricultural land and traces of phosphatic lithoclasts and bioclasts may only be encountered in ploughed fields and the debris from animal burrows. In 2015 temporary trenches were dug by the authors in the base of the Lower Greensand Group, Woburn Sands Formation (Late Aptian). Much poorly bedded and phosphate depleted Woburn Sands was exposed which is attributed to backfilled ‘Coprolite’ workings. However, one site provided exposure of undisturbed Woburn Sands resting unconformably upon the Upware Limestone Member, West Walton Formation (mid-Oxfordian, Late Jurassic) and the feather edge of the Ampthill Clay Formation (mid-Late Oxfordian). The sand contains rich concentrations of reworked phosphatised fossiliferous concretions of original Jurassic-Cretaceous boundary to mid-Aptian age and indigenous calcitic fossils, of Late Aptian age. This is the first time that in situ Woburn Sands have been exposed in the Upware area since the time of the coprolite workings and are documented photographically for the first time. A detailed stratigraphic succession has been recorded and new geological and palaeontological collections have been made from accurately known levels at a precisely known site. New observations allow us to re-evaluate the early geological accounts and provide the opportunity to discuss more closely the relationships of the reworked faunas of Oxfordian to Aptian age, and in particular we draw attention to those faunas with affinities to the Jurassic-Cretaceous boundary deposits of the Spilsby Basin to the north. This work confirms the basic accuracy of Keeping’s earlier seminal account.

Editorial: Biographical Memoirs , Volume 68

Editorial: <i>Biographical Memoirs</i> , Volume 68

Raymond Charles Casey. 10 October 1917—26 April 2016

Raymond Casey was an internationally recognized expert in two entirely different fields—geology and philately. He achieved this despite leaving school at 14. By then he was already collecting and studying fossils from his home town, Folkestone, and in 1939, despite not having a degree, he obtained a post with the Geological Survey of Great Britain in the modest role of assistant to C. J. Stubblefield. After war-time service in the RAF, he returned to the Survey in a similar role, but spent much of his ‘spare time’ researching and publishing on Lower Cretaceous palaeontology and stratigraphy. His fortunes began to change when, at the age of 38, he was admitted to Reading University to study for a doctorate. His thesis on Lower Greensand stratigraphy and palaeontology was recognized as an outstanding study that led to major publications including a nine-part monograph of the ammonite faunas. Then, in the late 1950s, he also began to study faunas from Jurassic–Cretaceous boundary beds in eastern England as part of his official work and this led to him visiting the Soviet Union on several occasions from 1963 onward. On the first visit he met the academician Nalivkin in Leningrad, who, as well as being an eminent geologist, was a keen philatelist. This led to Raymond taking an enthusiastic interest in pre-revolutionary Russian postal history, which resulted in numerous publications and awards and, after his retirement, became his main focus of interest.

Gamma-ray log correlation and interpretation of Fitton’s and Casey’s stratigraphy with offshore borehole 99/16-1

The Chale Bay type section of the Lower Greensand Group (LGS) Atherfield Clay, Ferruginous Sands and Sandrock formations is characterised by members, bounded by hiatuses, formerly recognised (if not named as such) by Fitton as his ‘groups’ and Casey in defining ammonite zone and sub-zone boundaries. Subsequent work has shown that some of the formations of the LGS are recognised elsewhere on the Isle of Wight, in southern England and in northern France. Likewise, some members of the Atherfield Clay and Ferruginous Sands formations can be recognised beyond the Chale Bay type section. In this work, we have measured outcrop gamma-ray emission from the type section: gamma-ray peaks recognised on all datasets are used to attempt a correlation of the Lower Greensand Group between the Isle of Wight and an offshore borehole (99/16-1). This is partially successful, showing that Fitton and Casey’s stratigraphy maybe recognised basin-wide.

Asteroids (Echinodermata) from the Crackers Member (lower Aptian, Deshayesites forbesi Zone) on the Isle of Wight (UK), with a revision of fossil Pseudarchasteridae

Asteroids from the lower Aptian Lower Greensand of the Isle of Wight are described. Two articulated specimens are referred to the extant paxillosid family Pseudarchasteridae and transferred to a living genus, i.e., Paragonaster, P. wightensis (Breton, 1992). Isolated marginal plates are assigned to the widespread Cretaceous astropectinid genus Coulonia, and described as C. caseyi sp. nov. The Cretaceous genus Comptonia Gray, 1840 is referred to the Pseudarchasteridae and revised taxonomically, with the recognition of two species; C. elegans Gray, 1840 and C. bretoni sp. nov., Paragonaster wightensis is the oldest known member of the Pseudarchasteridae.

First description of sharks’ teeth from the Ferruginous Sands Formation (Aptian, Early Cretaceous) of the Isle of Wight

A small sample of selachian teeth is described from a glauconitic nodule from the Ladder Chine Member, Ferruginous Sands Formation, Lower Greensand Group, late Aptian, Early Cretaceous found near Walpen Chine on the Isle of Wight, UK. The selachian fauna contains the root of an unidentified lamniform shark, and some associated teeth of a synechodontiform shark, here identified as Synechodus tenuis. The difficulties associated with the definition of the three common Cretaceous species of Synechodus - S. dubrisiensis, S. nitidus and S. tenuis - are briefly reviewed. The described material represents the first records of fossil sharks from the late Aptian of the Isle of Wight.

A new ammonite fauna from the Walpenites horizon of the upper Aptian (Lower Cretaceous), Isle of Wight, southern England

The Lower Greensand Group on the Isle of Wight in southern England forms the basis for the Aptian ammonite biostratigraphy in western Europe mainly established by the work of Raymond Casey between 1960 and 1980. It thus became a world reference succession, due to many ammonite finds from excellent outcrops along the coastline of the Island exposing the fossiliferous Atherfield Clay and Ferruginous Sands formations. Nevertheless, some of the members of these formations only rarely contain ammonites: an example is the horizon containing Walpenites (Group X according to the classical nomenclature of Fitton), in the upper Aptian Epicheloniceras martinioides Zone. Hitherto, this horizon has yielded only very rare Walpenites, a cryptic micromorphic ammonite only known from the type specimen. We report additional specimens of this rare ammonite, unequivocally demonstrating that Walpenites is a heteromorphic ammonite with only a part of the early whorls coiled in a planispiral with whorls attached to each other. Furthermore, the new material allows us to regard Luppovia as a junior subjective synonym of Walpenites, a genus based on material from Kazakhstan and Turkmenistan. Additionally, a new fauna of small ammonites from the Walpenites horizon is described; it contains Epicheloniceras martinioides, E. subnodosocostatum, E. tschernyschewi and the heteromorph cf. Toxoceratoides. This has improved the biostratigraphical dating and correlation of the stratigraphical level herein called the Walpenites horizon and, in contrast to earlier ideas, it contains ammonites that are distributed almost globally in all major faunal realms.

The palynology and geology of the Lower Cretaceous (Aptian–Albian) of Munday’s Hill Quarry, Bedfordshire, UK

Early Cretaceous sediments of Aptian–Albian age outcrop at Munday’s Hill Quarry, Bedfordshire, England. Previous papers describing the section have resulted in different terminologies being applied. The Lower Cretaceous in Bedfordshire is represented by sediments belonging to the Lower Greensand Group and the Gault Clay Formation. Within the Lower Greensand Group in the study area the Woburn Sands Formation, are of Aptian–Albian age. Selected samples have been analysed for palynology. The analysis reveals diverse palynomorph assemblages, including well-preserved dinoflagellate cysts and sporomorphs. Comparison of the assemblages with published records indicates that the lower samples are of Late Aptian age. Forms recorded include common Kiokansium unituberculatum, Cerbia tabulata, Aptea polymorpha and Cyclonephelium inconspicuum. An Early Albian age is indicated for the uppermost sample.

The winter storms of 2013/2014 in the UK: hydrological responses and impacts

This paper outlines the hydrological aspects of the 2013/2014 winter flooding in the UK, as well as the impacts. The episode is considered in a long-term historical context and wider issues raised by the flood events are discussed briefly.

Micromechanics of quartz sand breakage in a fractal context

From a Quaternary science perspective, sand-sized quartz as well as silt-sized quartz is often acknowledged as final products of glacial abrasion through different evolution mechanisms. This view challenges the existence of any universal comminution process, which may relate the formation of detrital quartz sand and silt. The contribution of grain size, energy input, and crystalline integrity in the scale of quartz crushability has long been the matter of much debate. The present empirical work examines the micromechanics of sand-to-silt size reduction in the quartz material. A series of grinding experiments was performed on Leighton Buzzard Lower Greensand using a high-energy agate disc mill. Analogous conditions to glacial abrasion are provided due to the combined abrasion between grains' asperity tips, and also between grains and rotating smooth tungsten carbide pestle. Simulation of discontinuous grain breakage allowed the examination of grains' crystalline defects. To enable an objective assessment of micromechanics of size reduction, measurements of particle and mode size distribution, fractal indexes and micro-morphological signatures were made. The crushing approach was probed through varied grinding times at a constant energy input, as well as varied energy inputs at constant grinding time. Breakage pathway was inspected via laser diffraction spectroscopy and transmission light microscopy. Results suggested that the grain breakdown is not necessarily an energy-dependent process. Non-crystallographically pure (amorphous) quartz sand and silt are inherently breakable materials through a fractal breakdown process. Results also revealed that the internal defects in quartz are independent from size and energy input.

Teredolites Leymerie in the Lower Greensand Group (Cretaceous) of the Isle of Wight and the problematic ichnology of reworked clasts

Nineteenth-century references to clavate borings in woody substrates in the Lower Greensand of the Isle of Wight used a variety of names, but Teredo (a wood-boring bivalve, not a boring), Teredolithes (a junior synonym of Teredolites) and Gastrochaena (a bivalve borer of rock and shelly substrates, not a boring in wood) are all nomenclatorially incorrect. Borings in a beach clast derived from the Lower Greensand Group and recently collected from Sandown Bay, Isle of Wight, are referred to Teredolites isp. cf. T. longissimus Kelly and Bromley. This specimen confirms the presence of Teredolites in the Lower Greensand Group and demonstrates a common ichnological problem of beach clasts; borings, either fossil or modern, are incompletely preserved, making confident classification below the level of ichnogenus problematic.

Long-term development of a cultural landscape: the origins and dynamics of lowland heathland in southern England

The lowland heathlands of southern England comprise ca. 14 % of the total area of this habitat in Europe yet their history is poorly understood. This paper presents the first detailed palaeoecological evidence (combining palynological, microscopic charcoal and radiocarbon data) relating to the origin and long-term dynamics of heathland vegetation in southern England. Valley peat sites, situated on the Lower Greensand Group (coarse-grained sandstones) at Conford (Hampshire) and Hurston Warren (West Sussex) have been investigated. The sequence from Conford indicates the unusually late survival of Pinus sylvestris (to as late as ca. 6050 cal. b.p.) in southern England. This is attributed to edaphic factors and, after ca. 7050 cal. b.p., to frequent fires. After intervening phases of dominance by deciduous woodland, heathland vegetation became established in the proximity of both sites in the Late Bronze Age (ca. 3000 cal. b.p.) with increases in indicators of grazing and burning demonstrating an association between the development of heathland and human activity. Thereafter, the pollen and charcoal records show that the vegetation remained in a dynamic state as the scale and nature of human activity varied through time. Major expansions in the extent of heathland occurred relatively recently; after ca. 1450 cal. b.p. at Hurston Warren and after ca. 850 cal. b.p. at Conford. A review of the palaeoecological evidence suggests that the most intense use and greatest coverage of heathland in southern England probably occurred during the medieval to post-medieval periods.