Bagshot Beds Research Articles

Geological resources and their exploitation in the Berkshire chalklands of the later nineteenth century: a first survey

ABSTRACTThe Chalk Group downlands and the closely associated outcrops of early Tertiary sediments provided to farmers, estate owners, and business men during the later nineteenth and early twentieth century a wide variety of earth-materials that were exploited at many hundreds of sites for mainly local but also regional needs. Chalk was used for soil-conditioning, road metal, flooring and hard-standing, as a walling material, and for lime-burning and the manufacture of whiting and putty. The early Tertiary silts and clays (Reading Beds, London Clay, Bagshot Beds) that unconformably overlie the Chalk Group, together with the closely associated Clay-with-Flints, were the basis of a major building-ceramic industry (bricks, tiles, chimney pots, drain-pipes) that served both regional and local markets. More than ninety kiln sites are known. Flints present in or derived from the Upper Chalk were extracted at many sites for hard-core, rough walling, typically combined with brick, and for facing and repairing important buildings, such as Victorian churches. Today almost no physical evidence of these various activities has survived in the landscape. Pits and scrapes are no longer evident in the fields and along the lanes, and smoking chimneys no longer rise above estates, villages, and towns such as Reading and Wokingham. Improvements in transportation, and a lowering of transport costs, have effected a transformation of the landscape.

Palaeogene rivers of southern Britain: climatic extremes, marine influence and compressional tectonics on the southern margin of the North Sea Basin

Palaeogene fluvial deposits in southern Britain have four distinct and interesting characteristics. First, the river systems were initiated on a ‘blank canvas’ of Cretaceous Chalk left exposed and deeply eroded because of a relative fall in sea-level. Second, river hydrology was controlled by the abnormally warm, wet subtropical climate of the Eocene which includes several short-lived but intense global warming events. Third, the river systems occupied a lowland coastal belt at the southern margin of the North Sea Basin and nearly all of the fluvial deposits contain evidence for marine influence. Fourth, tectonic compression related to Alpine mountain building may (or may not) have been important in creating an undulating landscape of growth folds and basins which diverted river courses and controlled areas of deposition. This paper describes the distribution and morphology of Palaeogene fluvial deposits, focussing primarily on the Hampshire Basin where the two main fluvial intervals are represented by the Late Palaeocene to Early Eocene Reading Formation and the Eocene Poole Formation. The characteristics of the two contrasting mud-rich and sand-rich fluvial intervals are considered together with an assessment of the relative importance of inherited topography, inversion tectonics, climate change and source area in shaping the river systems and their deposits. A new model for the Poole Formation is introduced which considers the possibility that these rivers bypassed the eastern half of the present Hampshire Basin to feed sandy tidal deltas of the correlative Bagshot Sands in the present London Basin.

New Taxa and New Records of Coelomycetes for the U.K.

Summary. A new genus of coelomycetes, Pseudocytoplacosphaeria, typified by P coniicola sp. nov., is proposed, and the new species Ascochyta ulicis-caledoniensis, Phomopsis agrostidis, Phomopsis airae and Septocyta visci-britannica are described. In addition, the new combinations Phomopsis barbari (Cooke) Punith. and Septocyta visci (Bres.) Punith. & Spooner are proposed, and the following species are reported as new records for the UK: Ascochyta ligustri Sacc. & Speg., on Ligustrum, Ascochyta nigripycnidiicola Ondfej on Vicia cracca, Marssonina mali (Henn.) S. Ito on Malus sylvestris, Monochaetia cryptomeriae M. Wilson & Ford-Rob. on Taxus, Myxothyrium leptideum (Fr.) Bubik & Kabit on Vaccinium, Septoria inconspicua Berk. & M. A. Curtis on Plantago, Sphaceloma populi (Sacc.) Jenkins on Populus and Salix, and Stagonospora bellunensis (Speg.) Jorst. on Molinia. The fungi reported in this paper result largely from ongoing studies of the mycota of the Esher/Oxshott SSSI complex in Surrey, U.K Four new species, one of which represents a new genus, and five new British records from this site are presented, as well as further collections and new host records for Monochaetia cryptomeriae, previously published as British only from Scotland. Related studies on other British coelomycetes, which have identified a further undescribed species and three additional species new to Britain from other sites, are also presented here. The site at Esher/Oxshott covers an area of c. 400 ha and largely comprises acid, sandy soils (Bagshot Sands) supporting heathland as well as a wide range of other terrestrial and aquatic habitats. These include both ancient and secondary woodland composed particularly of Carpinus, Quercus and Fagus, with much Pinus and Betula, both of the latter being invasive onto the managed heathland. London Clay outcrops to the east of the area. Aquatic habitats present include ponds, streams, a spring line and bog, plus the bank of the river Mole. These areas often support Alnus glutinosa and Salix fragilis and in places sallows, mostly Salix cinerea subsp. oleifolia and S. caprea, are common. Almost the entire area is designated as a Site of Special Scientific Interest (SSSI) and parts are also designated as Local Nature Reserve. The fungi of the area have been collected and recorded for many years, early foray reports going back well over a century, e.g. Step (1895). Fairly intensive work has been undertaken during the past two decades, and to date well over 3000 species have been recorded for which voucher material of most is held in K or IMI. It is the holotype locality for at least 35 species to date, including 27 hyphomycetes, although no coelomycetes have been previously described from the area. There is as yet no comprehensive account of

Construction of a Palaeogene tide-dominated shelf: influence of Top Chalk topography and sediment supply (Wessex Basin, UK)

Palaeogene siliciclastic sediments (Reading and London Clay Formations) in the Wessex Basin record an upward change through four tidally influenced deposition systems. The lowest (Reading Formation) was deposited in estuarine and coastal plain environments. The overlying London Clay records discrete upward changes from deltaic, to mixed tidal flat, to tidal sandsheet (‘Bagshot Sands’). Erosional topography on the Top Chalk surface had an important control on deposition: (1) topographic lows controlled the initial sites of marine flooding and sedimentation; (2) lows would have acted as conduits for sediment delivery; (3) lows created additional accommodation by the compaction of thick mud fills; (4) lows may have formed preferential sites for delta growth. As topography was reduced by sediment infill, depositional units tended toward more sheet-like geometries. Heavy minerals reveal that an upward progradational/aggradational trend and the development of more sand-rich facies are related to a change in provenance toward sand-rich Cornubian sources.

Iron Transport and Retention in Ochre-Rich Watercourses

Ferrous and ferric iron concentrations were determined over two years in an ochre-rich watercourse originating from ferruginous strata in the Bagshot Sands, some 40 km to the west of London. The watercourse comprised a bog, 3 km stream and 200 years old wetland/lake system. The data were used to interpret iron transport and retention characteristics of this system and, by comparison and inference, of analogous systems contaminated by iron from other environmental and post-industrial processes. Assessments were made of the effectiveness and longevity of the wetland/lake system as a sediment trap and of the likely ageing behaviour, if left unattended, of modern constructed wetlands treating similar ferruginous discharges from abandoned coal mines.

IRON TRANSPORT AND RETENTION IN OCHRE-RICH WATERCOURSES

Mineral Resources EngineeringVol. 09, No. 03, pp. 357-375 (2000) No AccessIRON TRANSPORT AND RETENTION IN OCHRE-RICH WATERCOURSESMICHAEL J. CARLILE and A. WILLIAM L. DUDENEYMICHAEL J. CARLILEDepartment of Biology, Imperial College, Silwood Park, Ascot SL5 7PY, UK Search for more papers by this author and A. WILLIAM L. DUDENEYT. H. Huxley School for the Environment, Earth Sciences and Engineering, Imperial College, London SW7 2BP, UK Search for more papers by this author https://doi.org/10.1142/S0950609800000251Cited by:1 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail AbstractFerrous and ferric iron concentrations were determined over two years in an ochre-rich watercourse originating from ferruginous strata in the Bagshot Sands, some 40 km to the west of London. The watercourse comprised a bog, 3 km stream and 200 years old wetland/lake system. The data were used to interpret iron transport and retention characteristics of this system and, by comparison and inference, of analogous systems contaminated by iron from other environmental and post-industrial processes. Assessments were made of the effectiveness and longevity of the wetland/lake system as a sediment trap and of the likely ageing behaviour, if left unattended, of modern constructed wetlands treating similar ferruginous discharges from abandoned coal mines. FiguresReferencesRelatedDetailsCited By 1Spatial and temporal relationships between Eocene sand horizons and iron contamination in stream water in the Thames Basin west of London, UKJ.J. Barrott, A.W.L. Dudeney and P.J. Mason16 August 2013 | Geochemistry: Exploration, Environment, Analysis, Vol. 14, No. 1 Recommended Vol. 09, No. 03 Metrics History PDF download

Some geotechnical properties of the Claygate ‘Beds’ and Bagshot ‘Beds’ of south Essex

Abstract The Claygate Beds and Bagshot Beds are the uppermost formations of Eocene age in south Essex, the former resting on the London Clay. The Claygate Beds consist primarily of silts and clays with subordinate sands, whilst sands are more common in the Bagshot Beds. The paper describes the geotechnical properties of these two sedimentary units. The results form part of a larger study of the engineering geology of south Essex. The sands, particularly in the Bagshot Beds, are fine grained. All the sands are uniformly sorted and negatively skewed. Quartz is the principal minerals in these beds and in the fine material, mica, montmorillonite, kaolinite and chlorite figure in that order of relative abundance. The geotechnical properties of the silts and clays of both formations are generally similar. However, the plasticity of the Claygate Beds tends to decrease somewhat from the lower to the upper division and the range of plasticity is greatest in the upper division. This may be due to the greater variation in quartz content and montmorillonite content in the latter division than in the two others. The clays in both formations tend to have normal activity whilst that of the silts is both normal and active. The values of the undrained shear strength parameters, especially in the sandy material, are influenced by the amount of cement present, and the degree of interlocking of grains and the degree of compaction. The undrained shear strength of the silts and clays suggests that they range from soft to very stiff.

Case studies of construction dewatering in fine grained Eocene soils : Preene, M Ground EngngV26, N7, Sept 1993, P23–27

This paper presents several case studies of construction dewatering, involving excavations in low-permeability Eocene soils such as the Barton, Bracklesham and Bagshot beds. It discusses methods of estimating steady state flow rate. Although the strata described are present only in south east England, the case studies illustrate several important points that apply to fine soils in general. For fine soils, the principal drainage mechanism is consolidation of saturated soil, not replacement of pore water by air. Although the soils' moisture content can be reduced by only a few percent, excavations can be made considerably more stable by controlling pore pressures. This is illustrated by applying the theory of effective stress. It was found that particle size distribution (PSD) tests overestimated permeability by up to two orders of magnitude, compared with values back-calculated from recorded flow rates. The maximum in situ test result was usually a better estimate. For the case studies, permeability values, back- calculated from the performance of construction dewatering systems, were usually between 0.000001 and 0.00004 m/s. One case study showed that close sources of recharge can increase flow rate by an order of magnitude. Here, the Eocene soils may be overlaid by permeable gravels, so that recharge from gravels may be affected by minor geological features that must be assessed carefully in design.

An analysis of some of the factors affecting the current distribution of Badger Meles meles setts in Essex

AbstractAll the known Badger setts in Essex were resurveyed in the mid‐1980s to record any changes in Badger distribution and status, and any associated changes in habitat and land use, during the preceding 20 years. New setts were also located. Being on the edge of London, Essex has undergone many recent changes that might be disadvantageous to Badgers. It is subjected to a high demand for land to meet increasing housing needs, intensive arable farming is widespread and few undisturbed habitats remain. These are typical of the pressures facing the Badger population in many areas of north‐west Europe, and so Essex was an ideal area in which to look at the status of the Badger, and in particular the impact of human activities on a Badger population. Much of the county is unsuitable for sett construction, since it consists of London Clay and glacial tills, and the highest concentration of setts was found in the Bagshot Beds. Woodland is rare in Essex, but it was still the favoured site for sett construction. Although over half the county is devoted to arable farming, Badgers tended to avoid such areas, and also avoided close proximity to roads, particularly busy roads, for sett sites. Since much of the county is low‐lying, man‐made embankments were particularly important sett sites, and land‐reclamation activities have probably provided additional sites for Badger setts. The effects of human activities on Badger distribution and numbers in Essex are discussed.

Petrological Examination of Bronze Age and Iron Age Pottery from Hog Cliff Hill, Maiden Newton, Dorset

A group of predominantly Late Bronze Age - Early Iron Age pottery from Hog Cliff Hill, including sherds from haematite-coated bowls, was submitted for detailed fabric analysis in thin section under the petrological microscope. In addition, heavy mineral separation was carried out on four of the larger sherds. The object of the analysis was threefold: (1) to confirm the validity of a provisional fabric identification of the handspecimen (Table 1, printed), (2) to see if the fabrics might have been locally made or not, and (3) to compare the Hog Cliff Hill fabrics with certain other analyzed assemblages of roughly the same period in the region, e.g. Longbridge Deverill Cow Down, Eldon's Seat, Gussage all Saints and Rope Lake Hole. The site at Hog Cliff Hill lies partly on the Upper Chalk and partly on Bagshot Beds, closeby to Upper Greensand deposits, just southeast of Maiden Newton.

A Bracklesham—Bagshot Beds unconformity in the London Basin

A Bracklesham—Bagshot Beds unconformity in the London Basin

The role of a soil × dietary sulphur interaction in the impairment of copper absorption by ingested soil in sheep

SummaryFour repletion experiments were carried out to clarify the roles of molybdenum, sulphur and iron in the inhibition of copper absorption by ingested soils. In each experiment, groups of four to six hypocupraemic Scottish Blackface ewes were repleted for 21 days with diets containing CuSO4 and/or soil Cu and the responses in plasma Cu used to assess the availability of the Cu supplied.In Expts 1 and 2, three soils varying in Mo but high in Fe content and derived from Lower Lias Clay, Namurian Shale and Weald loam were added at 100 g/kg D.M. to diets of low (1·0) and high (4·1 g/kg D.M.) S contents: they provided 3·1, 2·8 and 0·1 mg Mo/kg D.M. respectively. When compared with groups given no soil, each soil increased plasma Cu repletion in the low S experiment and decreased it in the high S experiment. Inhibition was thus not completely dependent on soil Mo but dependent upon dietary S.Soils varying in Fe content were compared in the manner of the above experiments in Expts 3 and 4. Two Fe-rich soils, developed from the Upper Chalk and a Barton Clay and providing 2·8 and 1·5 g Fe/kg D.M., impaired Cu repletion on the high S diet but not on the low S diet. A soil, developed on a sand from the Bagshot Beds and providing only 0·15 g Fe/kg D.M., did not impair repletion but FeSO4, providing 0·8 g Fe/kg D.M. did so, irrespective of dietary S content. Ingestion of Fe-rich soils in a high S diet caused three-fold increases in rumen sulphide concentrations 5 and 24 h after feeding. It is suggested that soil ingestion impairs Cu absorption in sheep by trapping S as heavy metal sulphides such as FeS and releasing sulphide in the acid abomasum.

The provenance and diagenesis of Palaeogene sandstones of southeast England as indicated by heavy mineral analysis

Two distinct heavy mineral assemblages occur in the Palaeogene sands, one derived from the Scottish Highlands, characterising the Thanet Formation, the upper part of the Woolwich and Reading Fm., the Oldhaven Fm., the London Clay Fm., the Claygate Beds and the Bagshot Beds, the other being largely confined to the bottom bed of the Woolwich and Reading Fm., and being derived from the south, either the Armorican or Ardennes-Rhenish massifs. In addition, heavy minerals indicative of contemporary volcanism occur, both in the basal London Clay, and more abundantly, in the Thanet Fm., where euhedral grains of aegirine, arfvedsonite and apatite have been recorded. Post-depositional alteration is particularly marked in the Thanet Fm., where epidote, garnet, apatite, sphene and hornblende are progressively lost towards the top of the sequence as a response to acidic groundwater circulation associated with pre-Woolwich and Reading Fm. weathering.

Estuarine sedimentation in the Eocene of southern England

ABSTRACTA temporary section in the Cuisian Bagshot Beds, which has been mapped in detail, displayed estuarine sediments with interlayered sands and muds, fine sands, channel‐fill sands and intraformational (mainly mud clast) conglomerates. The facies show rapid lateral and vertical changes in grain size and bed form and a restricted suite of trace fossils including Ophiomorpha nodosa and Arenicolites sp.The sequence is shown to have been deposited in a subtidal channel where tidal, wave and fluvial processes were dominant at different times. The following points are considered to be characteristic of sedimentation in this environment: (i) correlation is difficult and facies predictability is low; (ii) there are frequent lateral facies changes from the channel to the subtidal bank environment; (iii) pene‐contemporaneous erosion removes considerable amounts of sediment; (iv) load structures may be exposed, eroded, buried and reactivated; and (v) muddy layers and bioturbated horizons offer similar resistance to penecontemporaneous erosion.

Palaeoecological investigations of a site at Hampstead Heath, London

OUR understanding of the vegetational history of Britain is based mainly on studies of peat-bogs, lake and kettlehole infills1: away from areas where such deposits exist, there is a paucity of information2. A multidisciplinary investigation of a deposit associated with a Mesolithic site on Hampstead Heath, North London, is providing rare evidence about man's effect on the vegetational succession of south-east England. The pollen spectrum indicates that Tilia rich forest existed until the elm decline, followed by continuing clearance episodes and heath formation. Seeds and beetle remains, which provide more precise information on local conditions, confirm the overall pattern of change from natural forest to cleared areas used for cultivation and grazing. The Mesolithic site of West Heath, Hampstead (TQ2566 8676), is being excavated by the Hendon and District Archaeological Society under the direction of Mr D. Collins3. The site stands on dry, acid Bagshot Sands, but environmental investigations have been carried out at West Heath Spa, a boggy area about 300 m to the south-east, where permanent waterlogging is maintained by a chalybeate spring. At this spot, samples for pollen, seed and insect analyses were collected at 5-cm intervals from below the modern root layer to a depth of 130 cm. Results of these studies are briefly described here.

Eocene, lower Bracklesham Beds, iron workings in Surrey

A temporary section of lower Bracklesham Beds near Wisley, Surrey is described. A sequence of pyritous clays was seen to rest unconformably on the Bagshot Sands beneath. The present form of this boundary as traced through the Thames Valley is determined as an irregular basin centred about Ottershaw, Surrey. Palynomorph identifications indicate a Lutetian age. Sideritic clay ironstones also occur in the deposit. These ironstones are considered to be the source of ore for a confirmed Iron Age iron industry. Iron and copper mills which operated in the vicinity during the 17th to early 19th centuries were probably engaged in forging rather than smelting processes.

The influence of geological factors on slope stability in the London clay of south Essex, England

Most unstable slopes in the London Clay of south Essex are situated in areas where the overlying Claygate Beds are present. The Claygate Beds contain layers of sand which discharge groundwater that softens the underlying London Clay, thereby inducing instability. Plasticity indices are lowest in the upper part of the London Clay, in which most instability occurs. Where the Claygate Beds are absent, slopes on the London Clay are locally stable at slightly steeper angles, or unstable as a result of oversteepening by rivers. In a few areas, slopes are unstable below hilltops capped by Bagshot Beds.

Nutrient Budgets for a Dry Heath Ecosystem in the South of England

The heathlands of southern Britain, with vegetation dominated by Calluna vulgaris, are found on soils of low fertility where factors such as grazing, exposure or fire, operate to prevent the establishment of tree species. Unlike the other factors, fire periodically removes the standing crop and much of the accumulated litter. The magnitude of the nutrient fund in the heather ecosystem and the losses of nutrients due to heather burning in Scotland and Northern England have been described by Robertson & Davies (1965) and Allen (1964). Little or no similar work has been published from heathland areas in southern Britain. In this paper, the processes of vegetation development and litter accumulation on an area of lowland heath in southern Britain are described and the status of older stands of Calluna are discussed. The areas of heathland to be described occur on soils derived from Bagshot sands in the Poole basin of Dorset. These heathlands were once a western extension of the New Forest heathlands (Moore 1962), but urban development has led to their separation from the main New Forest area. With this separation have come other changes in land use, an almost complete reduction of agricultural grazing, cessation of controlled burning if it ever existed and an end to the cutting of peat and furze (Ulex europaeus) for fuel and other purposes. It is suggested by Seagrief (1959) from his Wareham pollen diagrams, that the history of heathland in this area may extend back as far as early Atlantic times.

A Micro-fauna from the Bagshot Beds, Eocene, of the London Basin

THE highest Eocene deposits in the London Basin were originally described by Prestwich1 as the Bagshot Sands. He subdivided these sands into lower, middle and upper divisions. Today, these are recognized as the Bagshot, Bracklesham and Barton Beds respectively on correlation with exposures in the Hampshire Basin2,3. Research into the petrography and environment of deposition of the lowest of these divisions, the Bagshot Beds sensu strictu, has included an extensive search for a fauna in deposits which many authors describe as being almost unfossiliferous4,5.

50 YEARS in the Bagshot Sands

Apparent mean corrosion rates of 0.16 and 0.10 mil/year of grey cast iron have been found in soil of pH 7.8 containing carbonate and traces only of soluble chloride, sulphate and nitrate. These were the findings resulting from investigations made after the removal of two grey cast iron lamp standards (Fig. 1) from a position about 170 ft above sea‐level in Surrey.