Oxford Clay Research Articles

Compaction of fills involving stabilisation of expansive soils

Stabilisation of sulphate-bearing soils with lime/cement-based binders has always been problematic, owing to excessive sulphate-induced expansion. This paper reports on investigations conducted on the consistency and compaction properties of Lower Oxford Clay (LOC), a sulphate-bearing soil that has been difficult to stabilise in the traditional manner using lime. In the investigations, LOC was stabilised both in the conventional manner using lime as the control, and also using a wide range of sustainable stabilisers incorporating industrial waste and by-product materials. The sustainable binders included wastepaper sludge ash (WSA) used on its own, as well as binary binders comprising WSA–lime, WSA–Portland cement (PC) and WSA–ground granulated blastfurnace slag. The results obtained showed that the blended stabilisers incorporating WSA were able to modify the soil by reducing the plasticity index, coupled with good compaction, strength and volume stability properties. The findings suggested that there are economic and environmental advantages of utilising WSA and similar industrial by-products in the modification and compaction of soils, including sulphate-bearing clay soils, as equal or at times superior alternatives to the traditional stabilisers of lime and/or PC.

A new skeleton of the cryptoclidid plesiosaur Tatenectes laramiensis reveals a novel body shape among plesiosaurs

ABSTRACT Current knowledge of plesiosaurs of clade Cryptoclidia is constrained by a lack of fossils from outside the Oxford Clay deposits of England. Recent fieldwork in the Sundance Formation of the Bighorn Basin, Wyoming, has resulted in the recovery of significant new fossils of cryptoclidid plesiosaurs, including the small-bodied form Tatenectes laramiensis. A new partial skeleton of this taxon is reported here; it is the most complete and best-preserved example of the taxon found to date, comprising a complete dorsal vertebral series, many ribs and gastralia, and a complete pelvic girdle. This skeleton illuminates several unique features of the taxon, including a novel pattern of midline pachyostosis in the gastralia. In addition, a range of both axial and appendicular morphological features reveals that Tatenectes had a body shape unique among known plesiosaurs, characterized by extreme dorsoventral compression, and modest anteroposterior reduction. The combination of the new skeleton with information from previous finds allows the first reconstruction of the taxon. Tatenectes had a dorsoventrally compressed, oblate spheroid body shape, with a high skeletal mass concentration in the ventral elements. We hypothesize that these features were adaptations for increased near-surface stability, perhaps allowing access to above normal wave base, inshore environments in the shallow Sundance Seaway.

Sustainable stabilisation of the Lower Oxford Clay by non-traditional binder

Wastepaper Sludge Ash (WSA), an industrial by-product from the paper industry can possibly be utilised to modify certain engineering properties of soils for specific uses to conserve non-renewable natural resources. Sulphate-bearing clays (Lower Oxford Clay, LOC) stabilised with various stabilisers on the basis of WSA (such as WSA–lime, WSA–Portland cement and WSA–ground granulated blastfurnace slag) under controlled laboratory conditions. The stabilisers reduced the plasticity index (PI) and maximum dry density (MDD), increased the optimum moisture content (OMC) of LOC. The compressive strength of these stabilised clays was comparable to the clay stabilised by the traditional stabiliser lime (CaO) and was better when WSA was combined with ground granulated blastfurnace slag (GGBS) and with Portland cement (PC). This system also performs better in terms of linear expansion. The results therefore indicate environmental, economic, as well as technological benefits in utilising WSA as soil stabiliser.

A new partial skeleton of a cryptocleidoid plesiosaur from the Upper Jurassic Sundance Formation of Wyoming

ABSTRACT Cryptocleidoid plesiosaurs from the Upper Jurassic are well known from the Oxford Clay (Callovian) of the United Kingdom. The plesiosaurs of the nearly coeval Sundance Formation (Oxfordian) of North America are poorly known, but are thought to include two cryptocleidoid taxa: Pantosaurus striatus and Tatenectes laramiensis. Here we present two specimens recently recovered from the Bighorn Basin of Wyoming. The first specimen comprises three articulated adult cervical vertebrae and fragments of a fourth. This specimen preserves a posteriorly directed cervical neural spine, a character diagnostic of Pantosaurus striatus. It also resembles Pantosaurus in the morphology of its cervical rib articulations. The second specimen is a partial articulated skeleton comprising a complete pelvic girdle, dorsal, sacral, and caudal vertebrae, and numerous ribs and gastralia. This specimen displays a number of unique characters, including posteriorly directed dorsal, sacral, and caudal neural spines, highly autapomorphic illia, and a pathologically asymmetric pelvic girdle. Despite the lack of overlapping material, it is tentatively referred to Pantosaurus on the basis of posteriorly directed neural spines. These specimens represent the first significant adult material provisionally referable to Pantosaurus striatus, as well as the first posterior axial column and pelvic girdle.

Changes in Properties of Clay Surrounding Cast in situ Piles

Often pile load carrying capacity is derived from friction between pile and the surrounding soil. This magnitude of friction mobilised, in the main, depends on pile material, properties of the soil and method of construction. In terms of construction, piles may be either pre-formed or cast in situ. Cast in situ piles are formed by boring a hole and filling it with concrete. It is envisaged that water and both calcium and hydroxyl ions migrate from the fresh concrete to the surrounding soil and have an impact on soil properties. An experimental study was undertaken to examine the extent of soil (Oxford clay) around the pile was affected by fresh concrete. Time related study included load tests on model piles. The investigation showed that there was about 4% increase in the moisture content of the surrounding soil soon after fresh concrete was placed and with time this dissipated. It showed that there was an increase in both hydroxyl and calcium ions in the vicinity of the pile. These also affected the adhesion factor, which increased with time to a limiting value. Time related tests showed that there was a small increase in pile load capacity with time.

Effects of mellowing sulfate-bearing clay soil stabilized with wastepaper sludge ash for road construction

The main objective of this research was to investigate the effect of mellowing on the swelling properties of stabilized Lower Oxford Clay (LOC), a sulfate-bearing clay soil that has caused concern in the past due to expansion upon stabilization. Two stabilizers were used, quicklime and a more sustainable stabilizer — wastepaper sludge ash (WSA), an industrial by-product used on its own and in combination with either quicklime (CaO) or ground granulated blastfurnace slag (GGBS). Quicklime was used on its own as a control. Compacted cylinders of LOC stabilized with the various stabilizers were made either mellowed (compacted 3 days after mixing with stabilizer) or unmellowed (compacted immediately after mixing with stabilizer). The linear expansion of the stabilized cylinders during moist curing and subsequent soaking was monitored for a total of 100 days. The results obtained showed that the linear expansion of unmellowed stabilized LOC was significantly reduced, and thus in terms of swelling potential, mellowing was not beneficial in the LOC system investigated. The results observed also suggest that there are technological, economic as well as environmental advantages of utilizing WSA and similar industrial by-products, in the stabilization of sulfate-bearing and other clay soils, as an alternative to the traditional stabilizers of lime and/or Portland Cement.

Jurassic sedimentation in the Cleveland Basin: a review

Jurassic sedimentation in the Cleveland Basin: a review

Unfired clay masonry bricks incorporating slate waste

This paper discusses the potential of using slate waste generated from roofing slate production in the UK in the manufacture of unfired clay masonry bricks. Ground granulated blast-furnace slag activated by lime and Portland cement were used to stabilise Lower Oxford Clay incorporating slate waste in the preparation of laboratory cylindrical test specimens. The specimens were moist cured at room temperature (20±2°C) for between 3 and 90 days before testing for compressive strength. The drying and linear expansion behaviours of the test samples were assessed by means of moisture content measurement (at the age of testing) and linear expansion measurement after soaking the samples in deionised water. The strength of the cement-activated blended mixture was lower than that of the lime-activated mixtures. An environmental comparison of the unfired clay masonry bricks with mainstream construction (fired) bricks shows that the unfired clay bricks have good environmental characteristics over a range of important criteria. These results suggest that there is potential for using activated slag mixtures in the manufacture of bricks for low-cost environmentally friendly housing and energy-efficient masonry wall construction within the UK.

‘Old bones, dry subject’: the dinosaurs and pterosaur collected by Alfred Nicholson Leeds of Peterborough, England

Abstract Alfred Nicholson Leeds, F.G.S., amassed one of the largest collections of fossil vertebrates from a single geological horizon anywhere in the world. The Leeds Collection is world famous for its large marine reptiles, but also includes the remains of a fine range of dinosaurs and a fragmentary pterosaur. The Leeds Collection ornithodirans were almost exclusively recovered from the Peterborough Member of the Oxford Clay Formation, with a single specimen of a sauropod derived from the underlying Kellaways Formation. The Leeds Collection includes the remains of at least 12 individual dinosaurs representing at least eight taxa (with other remains currently generically indeterminate) and a single fragmentary rhamphorhynchid pterosaur. Perhaps most intriguingly of all, in 1898 Alfred Leeds discovered a probable reptile egg, later attributed to a dinosaur. Each dinosaur and the pterosaur from the Leeds Collection is discussed, and, where known, details of the provenance, a brief history of research and pertinent archive material are included to provide the most comprehensive and up-to-date survey of the Leeds Collection ornithodirans to date.

Unfired clay bricks: from laboratory to industrial production

This paper reports on the production of unfired clay masonry bricks at both laboratory and industrial scales. The laboratory-scale bricks were produced at the University of Glamorgan while industrial brick production was carried out at Hanson Brick Company in Stewartby, Bedfordshire. Lime-activated ground granulated blast-furnace slag and Portland cement activated slag was used to stabilise Lower Oxford Clay (LOC) for laboratory and industrial brick production. The engineering performance (strength) of the industrial-scale bricks (blended binder content around 7%) at the end of a 90-day moist curing period tends to be higher than that of the laboratory bricks (blended binder content of 13·1%). It was extremely difficult to make a thorough technical comparison of the overall engineering performance of the laboratory and industrial bricks owing to disparities in test methods, brick format (one solid and the other a frog brick) and mixing and compaction methods. However, a comparison of the strength and other properties required for practical application of unfired clay bricks with those of bricks currently used in mainstream construction was carried out. A comparison of the environmental profile was also conducted. The results suggest that there is potential for using unfired clay bricks for low–medium cost housing and energy efficient masonry wall construction within the UK.

The geology of the Corallian ridge (Upper Jurassic) between Gilling East and North Grimston, Howardian Hills, North Yorkshire

SUMMARY The northern edge of the Howardian Hills, running for 25 km from Gilling East to North Grimston, North Yorkshire, comprises a near-continuous ridge of Oxfordian limestones and calcareous sandstones, here termed the Corallian ridge. These strata rise gently from the Vale of Pickering up to a steep scarp face which overlooks underlying Oxford Clay to the south. The limestones and sandstones belong to the Corallian Group, which in the Howardian Hills includes the Lower Calcareous Grit, Coralline Oolite and Upper Calcareous Grit formations. The Lower Calcareous Grit Formation comprises a succession of fine-grained, calcareous or spicular, siliceous sandstones, and forms a prominent feature. The Coralline Oolite Formation underlies gently rolling hills leading down to the Vale of Pickering, and is composed of a series of oolitic and fine-grained limestones with subordinate calcareous sandstones and sandy limestones. The Upper Calcareous Grit is represented here largely by calcareous strata, the North Grimston Cementstone, and is only exposed in faulted inliers to the south. The sequence was laid down in a tectonically active area, and movement of faults during deposition of the strata in the Mid Oxfordian led to marked changes in thickness and lithology across the area. Complications caused by these penecontemporaneous movements have meant that, though the outcrop has been investigated by numerous geologists over the last 150 years, the exact sequence of strata present and its correlation with the Corallian sequence on the north side of the Vale of Pickering have long presented problems. Much that was uncertain about the geology of the area has been resolved through detailed mapping of the area west of Malton.

Compressive strength and microstructural analysis of unfired clay masonry bricks

This paper reports on the compressive strength and microstructure of unfired clay masonry bricks. Blended binders comprising of lime-activated Ground Granulated Blastfurnace Slag (GGBS) and Portland Cement (PC)-activated GGBS were used to stabilise Lower Oxford Clay (LOC) for unfired masonry brick production. The compressive strength of the stabilised bricks incorporating lime–GGBS–LOC was higher than that of PC–GGBS–LOC. Scanning Electron Microscopy (SEM) with a Solid-state Backscattered Detector (SBD) and Energy Dispersive X-ray (EDX) analysis was employed to obtain a view of the microstructure and to conduct an analysis on the morphology and composition of the dried unfired clay brick samples, after 28 days of moist curing. The analytical results together with the physical observations have shown the formation of Calcium Silicate Hydrate (C-S-H) gel and additional pozzolanic (C-S-H) gel. The quantification of the compound content of the unfired bricks showed the presence of Calcite (CaCO 3), Quartz (SiO 2), Alumina (Al 2O 3) and Wollastonite (CaSiO 8) crystals. Traces of other crystals were also detected.

Design thermal values for unfired clay bricks

This paper reports on a laboratory and theoretical method for determining the design values for thermal conductivity and thermal resistance of unfired clay masonry bricks from both experimental and theoretical design point of view. The paper describes the methodology of obtaining these values using the measured lower and upper lambda limits. In order to determine the basic design thermal value and the design thermal resistance, a Laser-comp FOX 200 thermal conductivity meter equipped with WinTherm32an software package was employed for the laboratory data collection and analysis. Lime or Portland cement (PC)-activated Ground Granulated Blastfurnace Slag (GGBS) binder was used to stabilise Lower Oxford Clay (LOC) for unfired masonry brick specimen production. The major influence of the design values on the thermal conductivity and thermal resistance are illustrated in this study, using two different types of unfired clay bricks (LG and PG) at 2% moisture content prior to test. This paper covers conductivity test for each unfired clay bricks within the temperature range 2.5–17.5 °C. The measured thermal properties of the unfired clay bricks were compared to the design thermal properties of fired bricks. The results were used to predict the design thermal values of unfired clay masonry bricks at varied density and moisture contents prior to testing. A comparison of the measured thermal values for the unfired bricks to the design thermal values of fired clay bricks can also be seen. The results demonstrate that the unfired clay bricks were able to comply with the design thermal requirements for clay masonry units, suggesting that the unfired clay bricks can be used for low-medium cost housing and energy efficient masonry structures.

A NEW OXFORDIAN PLIOSAURID (PLESIOSAURIA, PLIOSAURIDAE) IN THE CARIBBEAN SEAWAY

Abstract: A new pliosaurid, Gallardosaurus iturraldei gen nov. et sp. nov., was found in the Viñales area, western Cuba, in sediments of the Jagua Formation, middle–late Oxfordian. This new taxon is characterized by: wide participation of the premaxilla in the outer margin of the external naris; frontal not participating in the orbital margin; postorbital in contact with the jugal and squamosal; presence of anterior pterygoid vacuity; cultriform process of parasphenoid convex and exposed in palatal view; pterygoid flanges high; jaw articulation low relative to tooth row; trihedral teeth in cross‐section and with smooth ridges at least in the labial face. A phylogenetic analysis suggests that Gallardosaurus forms a clade with Peloneustes, the most common pliosaurid genus occurring in the Oxford Clay. The Caribbean Seaway was, at least since the Oxfordian, a corridor that permitted the interchange for marine biota between Western Tethys and Eastern Pacific realms. Among vertebrates, bony fish and long‐necked plesiosaurs prevailed. However, marine pleurodiran turtles, metriorhynchid crocodilians, ophthalmosaurian ichthyosaurs, and pliosaurids (G. iturraldei gen. nov. et sp. nov.) have also been found, as well as at least two species of pterosaurs, and one camarasaurian dinosaur. Among these reptiles there were off‐shore pelagic forms such as the ichthyosaurs and metriorhynchids, together with the pliosaurid G. iturraldei gen. nov. et sp. nov.; other taxa were presumably less pelagic, such as the pleurodiran turtles and the cryptoclidid plesiosauroids. Gallardosaurus iturraldei gen. nov. et sp. nov. would have played the role of an active predator taking advantage of nectonic fish recorded in the area.

Osteology of the cryptocleidoid plesiosaur Tatenectes laramiensis, with comments on the taxonomic status of the Cimoliasauridae

ABSTRACT Recent field work in the Bighorn Basin, Wyoming has recovered significant new material of the plesiosaur Tatenectes laramiensis. The majority of cryptocleidoid plesiosaurs have been recovered from Middle and Upper Jurassic units (Oxford and Kimmeridge Clays, respectively) in the United Kingdom, but Tatenectes laramiensis is one of at least two cryptocleidoids known from the Upper Sundance Member of the Sundance Formation (Oxfordian) of North America. Although poorly known, they bear directly on both the phylogeny and biogeography of the cryptocleidoid plesiosaurs. Here we describe new fossil material of Tatenectes, and reevaluate the phylogenetic position of this genus based on all known material. New material includes a partial skeleton comprising cranial elements, axial column, and a partial pectoral girdle, as well as an isolated humerus and vertebrae. The pectoral girdle closely resembles that of Muraenosaurus beloclis from the Oxford Clay, but is even shorter anteriorly. The cervical vertebrae are more compressed antero-posteriorly than in other Jurassic cryptocleidoids. The humerus is less derived, resembling that of Tricleidus seeleyi. Two most parsimonious trees were obtained, and the consensus tree solidifies the phylogenetic position of Tatenectes as being most closely related to the Oxford Clay taxon Kimmerosaurus.

Developing unfired stabilised building materials in the UK

This paper discusses laboratory tests on Lower Oxford Clay (LOC) stabilised using different levels of lime (L) or Portland cement (PC), with and without blending with ground granulated blast-furnace slag (GGBS). LOC is used by Hanson Brick Company Ltd in the manufacture of fired ‘London’ bricks at the Stewartby brick plant in Bedfordshire. The research investigated L-PC, L-GGBS and PC-GGBS blends to assess their potential for application in sustainable unfired clay building materials (bricks, mortar, etc.). Use of unfired materials reduces not only energy costs, but also environmental damage associated with the traditional firing process used in the manufacture of clay building components. Due to the high strength requirements of the building industry compared with, for example, stabilised highway pavement layers, a high maximum stabiliser dosage of 20% was used. For road construction, typical stabiliser dosages are 3–8% for lime and 3–5% for PC. In the current investigation, cylindrical test specimens were cured for 28 days at moisture contents of 25, 30, 35 and 40% before testing for unconfined compressive strength. Preliminary results show that the strength values for all stabilised material investigated was within the strength range of 737–2077 kN/m2 at 28 days, with L-PC blends tending to achieve lower strength values than L-GGBS blends. Overall results suggest that there is potential in using GGBS-based binders for the manufacture of unfired building components.

Using slag for unfired-clay masonry-bricks

This paper reports on an investigation on the use of ground granulated blast-furnace slag (GGBS) in the development of a sustainable unfired clay binder material for stabilised masonry-brick. The compressive strength of the stabilised masonry-brick, using a semi-processed industrial kaolinite clay soil and a ‘real’ clay soil (Lower Oxford Clay) commonly used in masonry clay brick manufacture were examined. In practice between 1 and 3 wt.% lime is needed for modifying the soil properties and between 2 and 8 wt.% lime for stabilisation. Due to the high strength requirement in the building industry in comparison with stabilised highway pavement layers for example, a high maximum stabiliser dosage of 20% was used. However, only a small proportion of this high stabiliser content (20%) was lime or Portland cement. Cylindrical specimens were made at moisture contents of 25, 30, 35 and 40%, and cured for 28 days, before testing for unconfined compressive strength. Preliminary results show that the strength values for the stabilised clay systems investigated were within the strength range of 65 to 2077 kN/m2 at 28 days, with the lime–Portland cement blends tending to achieve lower strength values relative to the lime–slag blends. The results suggest that there is potential for the use of GGBS in unblended binders for the development of unfired clay masonry bricks.

Experimental woodland establishment on brick clays in southern England

A series of long-term field experiments examining a range of reclamation options for the establish-ment of woodland on Oxford Clay soil-forming materials restored after landfilling is described. Hostile soil physical and nutritional characteristics prevent normal tree survival and growth, but the experi-ments show that there are limited options to alleviate these conditions. The combined results show that tree species of alder, poplar and willow planted on loose-tipped mounds are most suited to the soil conditions, although growth is slow. Application of organic fertilizers has mixed effects.

AN ORIBATID MITE (ARACHNIDA: ACARI) FROM THE OXFORD CLAY (JURASSIC: UPPER CALLOVIAN) OF SOUTH CAVE STATION QUARRY, YORKSHIRE, UK

Abstract: A single specimen of a new species of oribatid mite belonging to the genus Jureremus Krivolutsky, inKrivolutsky and Krassilov 1977, previously described from the Upper Jurassic of the Russian Far East, is described as J. phippsi sp. nov. The mite is preserved by iron pyrite replacement, and was recovered by sieving from the Oxford Clay Formation (Jurassic: Upper Callovian) of South Cave, Yorkshire. It is the first record of a pre‐Pleistocene mite, and the second species record of the family Cymbaeremaeidae, from the British Isles; also, it is only the third record of Acari from the Jurassic Period. The presence of a terrestrial mite in a sedimentary sequence of open marine origin is noteworthy, and suggestions for its mode of transport to the site of deposition are discussed.

Preserving the unpreservable: a lost world rediscovered at Christian Malford, UK

The small village of Christian Malford, Wiltshire (UK) is known to palaeontologists the world over because of the chance discovery of an astonishing fossil bonanza in the mid‐nineteenth century. Pits in the Jurassic Oxford Clay yielded thousands of specimens of exquisitely preserved ammonites, fish and crustaceans, but became most famous for squid‐like cephalopods and belemnites (collectively termed coleoids) with fossilized soft‐parts. The precise location of the find has remained obscure, until now, and a new attempt is underway to understand the ancient environment that triggered this unusual preservation.