Lower Greensand Group Research Articles

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.

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.

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.

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.

A review of hydrogeology and water resources on the Isle of Wight

Abstract The Isle of Wight is a small, heavily populated island, where complex and careful management is required to ensure sustainable use of water resources. Much of the island is underlain by permeable strata and groundwater is an important source of supply. Many groundwater studies were undertaken by the water provider and regulatory authority from the 1970s onwards, but this work is not publicly available. This paper reviews these previous studies and provides an overview of the hydrogeology of the island with particular focus on the Lower Greensand Group and the Chalk–Upper Greensand aquifer. As one of the areas in the UK to experience water shortages during the 1976 drought, the Isle of Wight became the focus for new strategies for the sustainable development of water, which included the exploitation of more marginal aquifers, water metering and an engineering solution to provide water from the mainland. Ensuring future water demand is managed sustainably in an area where aquifers are fully exploited is likely to rely on the twin-track approach of both further demand-management and unconventional water resource development, such as wastewater reuse or desalination.

Transgressive changes from tidal estuarine to marine embayment depositional systems: The Lower Cretaceous Woburn Sands of southern England and comparison with Holocene analogs

The Lower Cretaceous Woburn Sands (Lower Greensand Group) in southern England constitutes one of the most intensively studied tidal sandstone outcrops for sedimentological and reservoir analog studies. Most recent workers have interpreted the whole 30–60-m (100–200-ft)-thick succession around Leighton Buzzard as representing an ancient tide-dominated estuary. However, unequivocal estuary characteristics are limited to the lowermost part (about 15–20 m [50–66 ft]). We suggest that a significant portion of the Woburn Sands, and most of the middle part, was formed in a tide-dominated marine embayment. Hence, the vertical facies change from the lower to middle part of the Woburn Sands is interpreted as a change from (1) a narrow estuary to (2) a broad marine embayment. The Wash embayment in eastern England is a striking modern analog; it receives most of its sediments and waters from marine sources and is largely filled with nondiluted seawater. Moreover, the Holocene transgressive history of The Wash is remarkably similar to the transgressive evolution of the Woburn Sands. Early estuarine sequence models predict landward translation of facies zones along the valley thalweg during transgression, but eventual facies translation in the strike direction has not been fully documented or discussed. An embayment facies that is not commonly confined in the early incised valley can occur vertically between the estuarine valley fill and marine shelf deposits and is probably underrepresented in current models. However, this segment of the transgression, comprising along-strike bay expansion and the development of a broad marine embayment, may be more important than previously thought.

Tamarugite on the Isle of Wight, UK

AbstractTamarugite (NaAl(SO4)2.6H2O) occurs at Compton Chine (NGR SZ 36808513), on the Isle of Wight, U.K., as globular encrustations covering an area of 2.8 m2 on argillaceous pyritous siltstones of the Lower Greensand Group, Lower Cretaceous. It is proposed that the production of H2SO4 from oxidizing pyrite in the siltstones releases Al ions from the argillaceous sediments, the Na content being acquired from sea spray. An analogy is made between Compton Chine and an occurrence in Victoria, Australia.

Facies analysis in the Lower Greensand using ground-penetrating radar

This paper presents the results of a ground-penetrating radar survey in the Woburn Sands Formation, Lower Greensand Group near Leighton Buzzard. A total of almost 4 km of survey has been acquired to investigate the internal structure of the sands. The radar survey achieved a resolution on the order of tens of centimetres with penetration up to 10 m and revealed a variety of horizontal, dipping and curved reflectors. The reflections are interpreted using seismic interpretation methodology. Two scales of unconformity-defined radar sequences are described. First-order radar sequence boundaries can be identified at the termination of primary reflectors. Second-order radar sequence boundaries can be identified at the terminations of both primary reflectors and first-order surfaces. First-order radar sequence boundaries are interpreted as reactivation surfaces within bedforms which are produced by changes in bedform geometry in response to a change in hydraulic regime or superimposed bedforms. Second-order surfaces are interpreted as the product of bedform migration. Reflection character and geometry are described and form the basis of a ground-penetrating radar facies analysis. Nine different radar facies have been identified. These are interpreted as large sets of planar cross-stratification, sets of trough cross-stratification, cosets of cross-stratification, tidal bundles, clay drapes, diagenetic concretions and possibly bioturbated sands. A reconstruction of the bedforms suggests that they were formed by very large curved crested dunes. These interpretations are checked against outcrop as the sands are excavated in working sand pits.

Correlation of the Hythe Beds Formation (Lower Greensand Group: early-mid-Aptian), southern England

The outcrop and sub-surface stratigraphy of the Hythe Beds Formation shows a coarsening-up cyclicity in the arenaceous successions of the western Weald Basin (Hants. & Surrey), and in the glauconitic/argillaceous deposits of Sussex/Kent. Correlation can be achieved through the identification of hiatus surfaces, the most distinctive of which are dark, smectite-enriched clays with belemnites and phosphate nodule beds. These beds are interpreted to be the product of transgressive conditions. Correlation may be difficult in clastic shelf successions: the use of distinctive transgressive event beds provides a model for other successions displaying similar facies.

Goethite ooids: growth mechanism and sandwave transport in the Lower Greensand (early Cretaceous, southern England)

AbstractThe Woburn Sands (Lower Greensand Group, Aptian–Albian age), in Billington Crossing quarry, Leighton Buzzard, Bedfordshire, England, show, along bedding planes of tabular cross-stratification, foreset alternations of quartz grains and goethitic ooids. Field and petrographic evidence suggest that: (a) the goethite in the layers and cores is primary; (b) the ooids formed by mechanical accretion of original Fe-hydroxide gels around nuclei on the sea-floor in shallower nearshore adjacent environments; (c) goethite cores of some ooids represent an earlier stage of iron deposition within the sediment where silica adsorbed by the iron-gels segregated in inclusions; (d) short-term variations in current strength and iron supply are responsible for the different arrangements of goethite platelets (tangential to random to radial) in the ferruginous layers in connection with the degree of crystallization of the colloidal iron during the accretion stage; (e) the ooids were then swept away in deeper waters by tidal action where their segregation in the lower parts of each foreset lamina is believed to have been hydraulically controlled.