Oolite Series Research Articles

A Monograph of the Ammonites of the Inferior Oolite Series by Sydney SavoryBuckman (in two volumes, including supplement). Cambridge University Press, Cambridge, 2015. No of pages: 1‐312 + 313‐456 + 1‐262. Price: Volume 1 UK£33‐00; Volume 2 UK£40‐00. ISBN 978-1-108-08433-8 (volume 1) and 978‐1‐108‐08432‐1 (volume 2) (paperback).

This monograph is a vital source of reference to the library of both researchers and amateurs engaged in the study of Lower Middle Jurassic ammonites. It remains the most comprehensive atlas of morphospecies found in strata of the Aalenian to Lower Bajocian part of the Inferior Oolite Group, particularly the Graphoceratidae and Sonniniidae. The original was issued in 14 parts, some of which are now of extreme rarity. The present volume succeeds in compiling the entire work in a paperback format in two volumes mirroring exactly the content of the original and reducing the space taken up on the bookshelf due to the use of lighter weight paper. The plates are of a slightly less good resolution, some with reduced contrast. Buckman strived to depict figured specimens at actual size; however, in this publication, the scale used has reduced them slightly. Although of minor importance, this discrepancy is not brought to the reader's attention in the preface to the new volumes. Sydney Savory Buckman (1860–1929) spent his early life at Bradford Abbas in Dorset where he was able to study first hand specimens obtained from local exposures, mostly with good stratigraphical provenance. By the time he commenced his monograph (1887), he had taken up residence in Gloucestershire and was advancing his knowledge of localities there. He had a sound grasp of time-rock duality and the need for a terminology to enable written discrimination of the morphologies he observed. He devised a vocabulary to facilitate this. While this may be of historical interest, it does nothing to clarify some of his descriptions and much of the terminology employed in his monograph was never widely used. Buckman's keen eye for slight differences of morphology led to him become a prolific taxonomic ‘splitter’, erecting numerous generic names throughout his work, some of which have been abandoned through synonymy. Due to the time over which the monograph continued, Buckman considered it necessary to revise some of his earlier conclusions in a Supplement (1898–1907), to designate many additional type specimens and to include a number of ‘in-text’ figures as photographs; the reproduction of which is good in the new volumes. In 1907, further parts of the monograph were abandoned due to disagreement with the Council of the Palaeontographical Society. Major ammonite families of the Bajocian and Lower Bathonian are therefore absent from the monograph; however, the treatment of taxa included still represents a fundamental source of reference relevant to the global study of Jurassic ammonites and is a classical work of historical interest. The new volumes are priced reasonably, of sturdy construction with a wipe-clean, attractive cover that depicts miniature images of some of the ammonites included. Ideally, a modern revision of the genera in this monograph should have been included as an appendix as a large number of the described taxa have undergone extensive revision after Buckman's time.

The hydrogeochemistry of the Jurassic limestones in Gloucestershire, England

Summary This study is a review of the major and minor chemical constituents in groundwater in the Jurassic limestones of Gloucestershire, England. Particular emphasis has been placed on the identification of hydrogeochemical processes. Groundwaters in the limestones of the Great Oolite Series and the Inferior Oolite Series, where they are unconfined, are of the Ca, HCO 3 type. In areas where both limestone series are confined beneath clays there is a gradual change in the chemistry to a Na, HCO 3 type. Deep within the confined limestones, particularly in the Great Oolite series, an Na, Cl component has been identified. Natural heavy metal concentrations are generally very low except where old pipework has influenced the Pb or Zn content. Significant down-dip chemical changes in terms of redox conditions, pH, dissolved oxygen content, ion-exchange and the concentrations of minor constituents are exhibited by groundwaters in the limestones of both series. An oxidation-reduction zone has been defined in each limestone unit. In the Inferior Oolite the zone occurs some 8 km down-gradient from the onset of confined conditions. In the Great Oolite a similar zone occurs 1–2 km into the confined area. The delay in the onset of reducing conditions in the Inferior Oolite is tentatively attributed to leakage of Great Oolite water through the intervening Fullers Earth.

Quantitative analysis of strain heterogeneity as a function of temperature and strain rate

Natural rock deformation is characteristically heterogeneous on all scales. Through experimental deformation of a typical oolitic limestone, under upper crustal conditions, an attempt is made to evaluate the relative influences of temperature and strain rate upon the promotion of strain homogeneity. The material used was selected on the basis of such criteria as a simple diagenetic history and an absence of previous strain history. This approach leads to the expectation that the rock in question, a Mesozoic limestone from the Oolite Series of the British Jurassic, might be realistically comparable to the condition of relatively young carbonate rocks in such structures as the Helvetic nappes of the European Alps at their time of deformation. Accordingly, specimens of oolitic limestone were deformed at a common confining pressure of 200 MPa, at temperatures of 25°, 100° and 200° C, and at strain rates extending over three orders of magnitude from 10 −4 to 10 −6 sec −1. Subsequent strain analyses were made on photographic enlargements of thin sections of the whole of each deformed sample cut in the plane containing the maximum and minimum dimensions of the distorted ooids. A qualitative view of the degree of strain heterogeneity is obtained by contouring strain variability and fully quantitative measure is obtained by expressing the degree of shape fluctuation as a coefficient of determination obtained from the leastsquares fit of the ooid axial data. For samples shortened to 40% at a strain rate of 10 −4 sec −1, the homogeneity coefficient ( r 2) ranged from 0.17 (25°C) to 0.42 (200°C), whereas at the slower rate of 10 −6 sec −1, the coefficient ranged from 0.56 (25°C) to 0.73 (200°C). Under all circumstances, but especially at temperatures above 100°C, strain rate is very much more effective than temperature in promoting a higher degree of strain homogeneity.

A palaeoecological study of a Cotswold Great Oolite Fossil-bed (English Jurassic)

Analysis of the Bradford Clay fauna of a micritic seam in the Great Oolite Series (Bathonian) of the mid-Cotswolds shows a large and displaced clear-water epifauna, mixed with ooliths and shell-debris, and a small indigenous mud infauna. Comparisons are made with calcareous sediments in the existing Bahaman and Trucial Coast seas: it is concluded that the fossil bed represents a subtidal accumulation of organic remains, inorganic debris, and fine calcareous particles, due to rough coastal seas.

Carbonate facies variation within the Osmington Oolite series in Southern England

The Osmington Oolite Series is of Upper Oxfordian age, and reasonable correlation within it is available on ammonite evidence. Being only part of a single Jurassic Stage, the series spans a very short period of geological time. Five major carbonate facies are defined on the basis of distinctive lithological assemblages. From south to north along the outcrop, the facies are: 1. (1) True Oolite Facies. This type contains coarsening upwards units of oosparites and pisolites and lenses of oosparites separated by phyllosilicate clays, Rhaxella biomicrites and intramicrites. An intertidal oolite shoal environment is suggested for these deposits. 2. (2) Oolite Freestone Facies. This facies is dominated by rounded lumps derived from the Coral Limestones to the north and contains large (15 m thick) accretion sets. 3. (3) Coral Limestone Facies. These sediments accumulated in a coral patch reef environment, in which formed coral biolithites and coral debris biomicrites. 4. (4) Wheatley Limestone Facies. This facies consists of fine skeletal debris, largely micritised, that was swept northwestward off the reef area. 5. (5) Phyllosilicate clay facies. These sediments formed the non-carbonate clay background sedimentation to the other facies, and fill inter-reef channels. A facies model is constructed from descriptive data, and suggests that the observed paleocurrents were of tidal origin. East-west ebb and flow was dominant in the True Oolite Facies, but north of this tidal flooding to the northeast predominated. The facies pattern within the Osmington Oolite Series was influenced by the morphology of the underlying banks of quartz sand. Where the latter are thickest (between Swindon and Oxford) carbonate deposits with the highest energy indices (coral biolithites) accumulated.

Primary Structures in the Middle Jurassic Great Oolite Series, Southern England: ABSTRACT

Primary structures observed in the Great Oolite Series include planar, wedge-shape and lenticular cross-stratification, current and interference ripples, micro cross-lamination, dunes, pseudonodules, loadcasts, graded bedding, mudcracks, groove casts, current lineation, prod marks, and bounce casts. These structures are grouped into two environmental and petrographic combinations. High-energy, channelled, shelly-oolitic limestones (grainstones) are characterized by vertical sequences consisting of a basal zone of imbricated shell fragments, a middle zone of thick sets of planar and lenticular cross-stratification, and an upper zone of interference and current ripples and wavy beds. The cross-strata show two dip directional maxima which are 180° apart, possess a high dip angle (26° average) and contain thin (1-1.5 in.) graded beds. These graded cross-strata consist of a shell chip zone which grades upward into coarse-grained oolite and fine-grained oolite. The shelly base of such a graded bed thickens and increases in particle size downslope. The oolites were deposited by normal flow in a lower flow regime, whereas the shell chips were deposited by cou ter eddies eroding the basal channel shell lag concentrate. The primary structures in the channelled limestone were formed in a lower flow regime operating in intertidal zone channels. Low-energy, even-bedded, oolitic clayey limestone (packestone and wackestone) are characterized by thick (1-5 ft.) graded beds, load casts and cross-stratified grainstone lenses. These cross-strata are low angle (average dip is 18°) and are current lineated if the limestone contains 15-25% quartz sand. The graded beds grade upward from coarse-grained oolite to clay-size carbonate particles. The top of each graded bed is bored and plastered with oyster shells in life position. These graded beds were formed by periodic sea-level oscillations which transgressed subtidal deposits across low and then high tidal flats. The cross-stratified grainstone lenses represent a beach or barrier bar marginal to the intertidal zone. End_of_Article - Last_Page 534------------

A Study of Micro-Arthropod Communities in Mineral Soils Near Corby, Northants

Many of the animals comprising the soil fauna appear to be very susceptible to small changes in micro-environment and undergo enormous fluctuations in numbers which suggests that competition for these resources must often be intense. The resulting community pattern observed must therefore be an integrated response to the environment in its broadest sense. Comparison of seasonal changes in community patterns in different soils allows one to detect those features which vary with time and thus to distinguish those that are indicative of fundamental differences in soil condition. The present work was done in an area where land is being reclaimed following open-cast quarrying for ironstone. Thus it was possible to select sites which represented various stages in the reclamation process and to examine the fauna to see whether any succession of species was apparent. After an initial survey, three sites were selected for intensive study on land owned by Messrs. Stewarts & Lloyds Minerals Ltd. and situated 2-3 miles NE of Corby, Northants. The first of these, Site 0, was on the southern edge of the Prior's Hall reclaimed land (National Grid Reference SP 934917). It occupied a small tongue of land of about I acre levelled in 1949 but not included within the field boundaries and thus not sown with grass and lucerne in 1955 like the rest of the area. It was dotted with coltsfoot (Tussilago farfara L.) and small grass tussocks but for much of the year was predominantly bare ground. The second, Site 1, was chosen from among fields of the Deene reclaimed land (Grid Ref. 913917). This field of about 6 acres had been sown to grass in 1948 and was thus one of the oldest experimentally reclaimed fields in the district. For comparison with these two, Site 100 (Grid Ref. 936926) was an area of more mature grassland; it had long been parkland and after arable cultivation from 1940 to 1946 had been returned to permanent pasture. While Site 100 had not been affected by quarrying operations, the other two areas shared a similar history of excavation by face shovels resulting in permanent loss of topsoil and mixing of the various geological strata lying above the ironstone beds. Left originally in series of parallel ridges called 'hill and dale' they were levelled by filling in the hollows and thus the final surface would consist of a mosaic of subsoil types from the Great and Inferior Oolite Series comprising sands, silts, heavy clays and sandy limestones.

The Composition of Marls and Limestones in the Great Oolite Series of Oxfordshire

AbstractAnalyses of eighteen samples from Jurassic marls and limestones show a large, continuous range in carbonate-clay composition. The significance of the carbonate/clay ratio is discussed, and it is show that rapid lateral and vertical transitions from marl to limestone may either reflect major changes in composition or represent only small shifts (across a critical value: 4) in the carbonate/clay ratio. The term “marl” is defined.

A marine shell-bed near the base of the Estuarine Series in Raasay

The purpose of this paper is to place on record the discovery of a marine shell-bed near the base of the Estuarine Series of the Jurassic succession in the island of Raasay in the Inner Hebrides. The author acknowledges with thanks the assistance of Dr. Martin Bott, Mr. C. R. Thewlis and Mr. D. Williams who all took part in the discovery. He also records his grateful thanks to Dr. L. R. Cox who identified and commented upon the lamellibranchs and to Dr. F. W. Anderson who identified the ostracods and crinoids collected from the shell-bed. The field work was carried out with the aid of a grant from the Clough Memorial Research Fund, which is gratefully acknowledged. In the Hebridean province of the British Jurassic rocks, the Inferior Oolite Series is followed by strata of estuarine origin known as the Great Estuarine, or simply the Estuarine, Series. This series is regarded as the equivalent of the Great Oolite Series of southern England, but may include at its base strata of inferior Oolite age as well. Arkell (1933, p. 246) noted that the topmost ammonite zones of the Inferior Oolite have not been found in the Hebrides, but the succession upwards from the highest known beds in that Series, namely those of the Garantiana Zone , was believed by Lee to be a conformable one. He stated (1920, p. 53) that in Raasay, “The actual base of the series” (i.e. of the Estuarine Series) “is marked by an oil-shale, 8 to

Field meeting to examine the Great Oolite Series of Oxfordshire: 7 August 1955

Field meeting to examine the Great Oolite Series of Oxfordshire: 7 August 1955

A Survey of the Mollusca of the British Great Oolite Series Primarily a Nomenclatorial Revision of the Monographs by Morris and Lycett (1851–55). Lycett (1863) and Blake (1905–1907). Part I Pages i–xiii, 1–48, Revised Explanations of Plates, Morris and Lycett (Bivalves) I–XV

(1948). A Survey of the Mollusca of the British Great Oolite Series Primarily a Nomenclatorial Revision of the Monographs by Morris and Lycett (1851–55). Lycett (1863) and Blake (1905–1907). Part I Pages i–xiii, 1–48, Revised Explanations of Plates, Morris and Lycett (Bivalves) I–XV. Monographs of the Palaeontographical Society: Vol. 102, No. 444, pp. i-48.

Rhynchonellids of the Boueti Bed of the Great Oolite Series of Langton Herring, Dorset: A Study in Variation

(1) The range of variation in the external characters of the rhynchonellids examined is illustrated by means of graphs and scatter-diagrams.(2) The three-variable scatter compares directly the proportions of thickness, breadth, and length, and defines the assemblage as adequately as several scatters which relate only pairs of variables. A close relationship is shown to exist between the three-variable scatter in which the positions of specimens are mathematically determined and the scatter in which the specimens are placed according to general appearance.(3) The three-variable scatter, when considered with size-groups, indicates that with growth, breadth and thickness increase more rapidly than does length. All the scatters indicate that proportionate thickness Varies to a greater degree than does proportionate breadth or proportionate length.(4) The sample, being random, is probably nearly representative of the goniorhynch rhynchonellid fauna of the Boueti Bed at Langton Herring. The stratigraphical value of the work, however, can only be proved by examination of assemblages from other localities and horizons.(5) Since the scatters show that all gradations occur between the extreme variants, the forms behave as though belonging to a single homogenetic community. It is recognized that internal characters may in due course be found to show discontinuity in their variation, but on present evidence it appears that only one species is present.

A Deep Boring at North Creake, Norfolk

Summary1. The North Creake boring shows the Chalk up to the Coranguinum zone to be appreciably thicker than at the nearest outcrops. The Chalk rests upon fine-grained Upper Greensand (possibly Albian) which is developed in addition to the normal Red Chalk.2. The “Lower Greensand” is developed much as at outcrop, but the Sandringham Sands are thickened by one-third. There is a strong indication of a stratigraphical break in the middle of the Carstone, which may mark the boundary between the Aptian and Albian stages.3. The Kimeridge, Corallian (Ampthill), and Oxford Clays are developed as in the King's Lynn district, and (in contrast to Southerey) normal Kellaways Beds rest on Cornbrash.4. The upper part of the Great Oolite Series is in Blisworth Clay facies. The “Limestone” is raggy and non-oolitic.5. The Great Oolite rests directly on bituminous shales which are believed to be of early Upper Lias date. The Middle and Lower Lias are well developed, but the latter is attenuated as a whole. There is a possible representative of the Lower Rhaetic.6. The Trias is represented by varicoloured marls (Keuper) upon pale grey sandstone (probably Bunter). The latter rests directly on pre-Cambrian rocks comparable with tuffs and agglomerates of Chamwood.

The Yorkshire Dogger: III. Upper Eskdale

1. A sequence of strata is determined in the Dogger of Upper Eskdale and its tributary valleys. The rocks fall into three main series, which are subdivided into groups.2. The underlying Yeovilian sediments, originally included with the Dogger, are mapped and briefly described. The unconformity between them and the Dogger is emphasized.3. The Dogger is marine throughout but only the oldest yields an adequate faunal assemblage, similar to that of the Glaisdale Oolite Series (upper opalinum). The greater part of the Dogger of this area is therefore younger than that of the Yorkshire Coast.4. Chemical changes in the sea-water caused the deposition of siderite to characterize the earliest phase (Glaisdale Oolite Series). This was succeeded by a phase of dominantly chamosite deposition (the Chamositic Series) followed by a reversion to siderite deposition (the Ajalon Series).5. Earth-movement controlled sedimentation over the area. During the first phase an eastern tilt to the region held the centre and west above or near sea-level, where it received no sediment. The second phase saw general depression with the accumulation of shallow water sediments. This was followed by uplift and erosion when a broad shallow valley was cut. Partial depression then flooded the valley with derived marine sediments.

Societies and Academies

LONDON Geological Society, March 8. D. A. BRYN DAVIES: The Ordovician rocks of the Trefriw district, North Wales. The area described extends from Trefriw and Dolgarrog in the Conway valley south-westwards to Capel Curig. The Glanrafon beds are correlated with the beds immediately underlying the Snowdon volcanic suite in Snowdonia, and with the beds of the same name underlying the volcanic suite at Dolwyd-delan. The Crafnant volcanic series is considered to represent an incomplete development of the Snow-donian suite, the bedded pyroclastic and probably also the upper rhyolitic series being absent. In the neighbourhood of Dolgarrog, the Crafnant series is faulted against a thick development of pumice-tuff and spilitic agglomerate overlain by rhyolite-tuff and rhyolite. These are regarded as contemporaneous with the Crafnant series, but representing, in part at least, the products of a different centre of activity. The fauna of the Llanrhychwyn Slates, comparing closely with that of the Lower Cadnant Shales of Conway, places the underlying volcanic series in the Llandeilian, and indicates its correlation with the upper part of the Conway Volcanic series. V. WILSON: The Corallian rocks of Yorkshire. (1) The Howardian Hills. Three divisions of the Corallian are recognised and their stratigraphical relations are dealt with in detail. The important role played by the spicular remains of the lithistid sponge Rhaxella perforata Hinde in the building up of the Lower Calcareous Grit is recognised for the first time. Calcareous, and many varieties of siliceous, spicules are described, and their distribution is discussed. Though perfect lithological continuity exists between the Lower Calcareous Grit and the overlying Osmington Oolite series, the absence of any representatives of the Hambleton Oolite series and the Middle Calcareous Grit containing fossils characteristic of these two divisions is considered to indicate the existence of a non-sequence in this area. In the later stages of the Osmington Oolite period reefs became established, and numerous facies deposits accumulated from the erosion of the reefs. As the Lower Calcareous Grit passes gradually into the Oxford Clay below, so the Upper Calcareous Grit gradually gives place to the overlying Kimeridge Clay in the North Grimston district, there being no unconformity such as was formerly supposed.

The Lower Oolites exposed in the Ardley and Fritwell Railway-cuttings, between Bicester and Banbury, Oxford

Summary The cuttings are shown to provide a key section for the understanding of the Great Oolite Series in the Southern Midlands, just where important changes take place between the limestone province of the south-west and the ‘estuarine’ province of the north-east. A detailed description of the succession is given and this is then correlated with other sections in the neighbourhood and the adjoining counties. Thick sandy strata which have been called Northampton Sands in previous published accounts are shown to be much younger in date—equivalent to the Chipping Norton Limestone. The whole of the Inferior Oolite Series (of which the Northampton Sands represent the basal zones) is found to be missing, as is also the upper or Yeovilian division of the Upper Lias. Limestones which succeed the sandy beds and which have previously been considered to be Chipping Norton Limestone are correlated mainly with the Taynton Stone of West Oxfordshire and Gloucestershire. Thick marly strata next in succession, previously correlated with the “Neaeran” Beds of North Oxfordshire, are shown to be a continuation of the Hampen Marly Beds of West Oxfordshire and the Cotswolds. A lateral passage is thus traced from the Hampen Marly Beds into the Upper Estuarine Series of Northamptonshire and the Eastern Counties. A detailed description of the White Limestone and “Forest Marble” is also given and the component parts are correlated with their representatives elsewhere.

Notes on the geology of Raasay

General Remarks. The geology of Raasay, although varied, is not of great complexity. The northern end of the island is rugged ground formed of Lewisian Gneiss, but the fundamental rock in the area to the south is the Torridon Sandstone. The Jurassic strata are faulted against this old group of rocks beyond Carn Dearg and South Screapadal on the north; and the red rocks of the Trias are seen to rest on Torridon Sandstone to the south-east of Suisnish Hill, by Eyre Burn, on the south. Macculloch in 18191 gave a capital account of the general structure of the island, noted the true sequence of the main rock-divisions, and recognised the Liassic aspect of some of the fossils. Eight years later, Murchison, who paid a visit to the Hebrides in company with Sedgwick, determined the occurrence of Lias, Inferior Oolite, and Great Oolite.2 Thirty years elapsed before any further attention was given to the subject. Then, in 1857, Sir Archibald Geikie constructed a geological map of Raasay on the scale of about 2⅓ inches to a mile.3 Six divisions of the Jurassic rocks were represented; these included the Lower Lias limestones and overlying Pabba shales, the Middle Lias Scalpa Beds, and three divisions of the higher sandstones and shales of the Oolitic Series. This survey was utilised in the preparation of the “First Sketch of a Geological Map of Scotland” by Murchison and Geikie, published in 1861, and in other maps issued by the latter author. The

III. A petrified Williamsonia from Scotland

The account of Scotch Jurassic floras given by Hugh Miller in the ‘Testimony of the Rocks’ deals chiefly with plants from the neighbourhood of Helmsdale, on the coast of Sutherland, and from Eathie, near Cromarty. The Sutherland species have recently been described in a paper published by the Royal Society of Edinburgh, which includes also a description of the majority of the Eathie specimens. Some of the latter were, however, reserved for separate treatment. It is the most interesting of these that forms the subject of the present communication. Miller referred the Helmsdale plants to the Oolitic series, and those from Eathie he regarded as Liassic. The great majority of the Sutherland plants are from rocks now recognised as Kimmeridgian, and there is no reason to suppose that the Eathie specimens are not, approximately at least, of the same age, though the limestone nodules in which they are preserved indicate by their weathered appearance and by the occurrence of pits made by boring organisms that they were picked up on the beach, and not found in situ .

VI.—On the Stratigraphical Distribution of the Inferior-Oolite Vertebrates of the Cotteswold Hills and the Bath-Doulting District

Vertebrate-Remains are by no means abundant in the Inferior-Oolite rocks of the Cotteswold Hills and Bath—Doulting Distriet. Mr. H. B. Woodward, F.R.S., has written—“The Inferior Oolite Series has yielded a rich and varied Invertebrate fauna, but the remains of Saurians and Fishes are very rare.“The Reptilia that have been found include Megalosaurus and Steneosaurus, and the Fishes are represented by Hybodus, Strophodus, etc.”

III.—Note on a Small Anticline in the Geeat Oolite Series at Clapham, North of Bedford

In the broad Alluvial tract which borders the Ouse between Oakley and Clapham, north of Bedford, there is a gravel-pit in which a small anticline of the Great Oolite was abruptly encountered amidst the regularly stratified river-deposits. The pit is situated immediately north of the Oakley road and east of the Midland Railway.