Ian West, Romsey, Hampshire
and Visiting Scientist atOcean and Earth Science ,
Webpage hosted by courtesy of iSolutions, Southampton University
Website archived at the British Library
Click here for the full LIST OF WEBPAGES
Home Page and Contents || Osmington - Introduction |Osmington - Osmington Mills to Ringstead |Osmington - Bencliff Grit |Osmington - Osmington Oolite | |Osmington - Black Head | Osmington - Corallian Fossils |
Osmington - Pt. 1 - Introduction
Osmington - Pt. 2 - Osmington Mills to Ringstead
Osmington - Pt. 3 - Bencliff Grit
Osmington - Pt. 4 - Osmington Oolite
Osmington - Pt. 5 - Black Head
Osmington - Pt. 6 - Corallian Fossils
Osmington - Pt. 7 - Bibliography
Purbeck Formation - Bibliography
Kimmeridge and Kimmeridge Clay - Bibliography
Osmington Mills and Corallian - Bibliography
Lias and Lyme Regis - Bibliography
References and Bibliography - Books and Papers
Allen , P.A. and Underhill, J.R. 1989. Swaley cross-stratification by unidirectional flows, Bencliff Grit (Upper Jurassic), Dorset, U.K. Journal of the Geological Society, London, 146, 241-252.
Arkell , W.J. 1927. Corallian rocks of Oxford, Berkshire and north Wiltshire. Philosophical Transactions of the Royal Society, London, Series B, 242, 283-246. [Not on Dorset but relevant]
Arkell, W.J. 1929. Monograph of the British Corallian Lamellibranchia. Palaeontographical Society Monographs.
Arkell, W.J. 1933. The Jurassic System in Great Britain. Clarendon Press, Oxford, 681 pp.
Arkell, W. J. 1935a. The Ammonites of the English Corallian Beds. Part 1. The Perisphinctids of the Dorset Trigonia clavellata Beds. Palaeontographical Society Monograph.
Arkell, W.J. 1935b. On the nature, origin and climatic significance of coral reefs in the vicinity of Oxford. Quarterly Journal of the Geological Society, London. 91, 77-110. [not on Dorset but dealing with the Corallian where coral reefs do occur.]
Arkell, W.J. 1935-1948. A Monograph on the Ammonites of the English Corallian Beds. Palaeontographical Society, London. 420 pp. 78 large plates, many folding, each with several monochrome photographs. Issued in 15 parts from 1935 - 1948 and bound together as one volume. By W.J. Arkell, M.A., D.Sc., F.R.S. [This classic large monograph contains much interesting material, and excellent illustrations. See particularly: Section 1. - The Perisphinctids of the Trigonia clavellata Beds of Dorset, and Section 5, Stratigraphical Conclusions, 4, Dorset. ]
Arkell, W.J. 1936. The Corallian Beds of Dorset. Part 1. The Coast. Proceedings of the Dorset Natural History and Archaeological Society, vol. 57 for 1935 (published 1936), 59-93. [Contents: Introductory and Historical, The Lithology and Bionomics of the Corallian Sea Bed, Ringstead Bay to Osmington Mills, Osmington Mills to Black Head and Shortlake, Ham Cliff, Redcliff and Jordan Hill, Weymouth: Nothe Point to Sandsfoot Castle, The East Fleet near Wyke, Broadway to Abbotsbury, The Abbotsbury Iron Ore, The Ammonite Succession, List of Works to which Reference is Made. .. The Corallian Beds of the Dorset coast attain a thickness of just over 200 feet. Deposited as they were during a predominantly shallow-water episode between the epochs of the Oxford and Kimmeridge Clays, they present exceptional variety and interest in both their palaeontology and their lithology....(This publication is the source of the standard maps and cliff sections and descriptions of the Corallian strata of Osmington Mills and elsewhere. Most have been reproduced in Arkell, 1947 - Memoir. There are photographs and details, however, which have not been reproduced).]
Arkell, W.J. 1947 (reprinted 1953). The Geology of the Country around Weymouth, Swanage, Corfe and Lulworth. Memoir of the Geological Survey, 386 pp.
Arkell, W.J. 1948. Oxford Clay and Kellaways Beds, Weymouth. Proceedings of Dorset Natural History and Archaeological Society, 69 (for 1947), 122-124.
Arkell, W.J. 1951. the structure of the Spring Bottom Ridge, and the origin of the mud-slides, Osmington, Dorset. Proceedings of the Geologists' Association, 62, 21-30. Abstract: A hitherto undetected normal fault explains several anomalies in the complicated geology around Osmington Mills, including the origin of the 'mud glaciers'. The Angular Flint Gravel is shown to be a weathered form of the Clay-with-Flints. Paper received 19 December 1949. By W. J. Arkell, M.A., D.Sc., F.R.S.
Arkell, W.J. 1956. Jurassic Geology of the World. Oliver and Boyd, London. 800 pp.
Blake , J.F. 1875. On the Kimmeridge Clay of England. Quarterly Journal of the Geological Society of London, 31, 196-237. By the Rev. J.F. Blake. M.A., F.G.S. (read January 13, 1875). [See particularly p. 198-199 "Section on the Coast at Kimmeridge, between Chapman's Pool and Hen Cliff. This lists from top downward 43 units. There is a summary of the fauna, in old terminology. Towards the end there is long faunal list and there are figures of 16 species of molluscs. Note that the paper considers the Kimmeridge over a wide area of England and is not as detailed on the Kimmeridge coast section, as might be expected. There is some detail on the "Kimmeridge Passage-Beds" of the Weymouth area, including Ringstead Bay and Osmington Mills.]
Blake , J. F. and Hudleston, W.H. 1877. On the Corallian rocks of England. Quarterly Journal of the Geological Society, London, 33, 260-405.
British Geological Survey (BGS). (Compiler Wood, M.A.) 2011. Geology of South Dorset and South-East Devon and its World Heritage Coast.
Special Memoir for 1:50,000 geological sheets 328 Dorchester, 342 West Fleet and Weymouth and 342/343 Swanage and parts of sheets 326/340 Sidmouth, 327 Bridport, 329 Bournemouth and 330 Newton Abbott. Compiled by M.A. Woods. By Barton, C.M., Woods, M.A., Bristow, C.R., Newell, A.J., Westhead, R.K., Evans, D.J., Kirby G.A., and Warrington, G. Contributors: Biostratigraphy - J.B. Riding; Stratigraphy - E.C. Freshney; Economic Geology - D.E. Highley and G.K. Lott; Engineering Geology - A. Forster and A. Gibson. British Geological Survey, Keyworth, Nottingham, 2011. 161 pp. This is the new version of the Geological Survey Memoir for the Dorset Coast etc. and replaces Arkell (1947) and the earlier memoir by Strahan (1898). It covers a wider area than these old memoirs, though, and includes all of "Jurassic Coast", UNESCO World Heritage Coast. It is a key reference work. Available from BGS Online Bookshop at 24 pounds stirling (in Jan. 2012).
Brookfield , M.E. 1970. Eustatic changes of sea level and orogeny in the Jurassic. Tectonophysics, 9, 347-363.
Brookfield, M.E. 1973. The palaeoenvironment of the Abbotsbury Ironstone (Upper Jurassic) of Dorset. Palaeontology, 16, 261-274.
Brookfield, M.E. 1978. The lithostratigraphy of the upper Oxfordian and lower Kimmeridgian Beds of south Dorset, England. Proceedings of the Geologists' Association , 89, 1- 32.
Bruce , P. 1989, 2nd Edition 1996, 3rd Edition 2001. Inshore along the Dorset Coast. Boldre Marine, Lymington. First edition has115pp + charts. 3rd Edition has 134 pp. By Peter Bruce. [Apart from its primary purpose for yachting, it very useful for local names and descriptions of coastal detail. It gives the names of offshore rocks and small headlands and bays. It cover the coastline from Christchurch Bay to Portland. The Third Edition has excellent colour plates including aerial photographs. ]
Buckland , W. and De La Beche, H.T. 1836. On the geology of the neighbourhood of Weymouth and the adjacent parts of the coast of Dorset. Transactions of the Geological Society, London, Series 2, vol. 4, pt. 1, p.1-46 .
Buckman , J. 1878. On some slabs of Trigonia clavellata from Osmington Mills, Dorset. Proceedings of the Dorset Natural History and Archaeological Field Club, 2, 79-80.
Buckman, S.S. 1909-1912. Yorkshire Type Ammonites. 1. London.
Buckman, S.S. 1913-1919. Yorkshire Type Ammonites. 2. London.
Buckman, S.S. 1919-1921. Type Ammonites. 3. London.
Buckman, S.S. 1922-1923. Type Ammonites. 4. London.
Buckman, S.S. 1923-1925. Type Ammonites. 5. London.
Buckman, S.S. 1925-1927. Type Ammonites. 6.London.
Callomon , J.H. and Cope, J.C.W. 1995. The Jurassic Geology of Dorset. In Taylor, P.D. ed. Field Geology of the British Jurassic. Geological Society, London, 51-104.
Cecca , F. Martin Garin, B., Marchand, D.. Lathuiliere, B. and Bartolini, A. 2005. Paleoclimatic control of biogeographic and sedimentary events in Tethyan and peri-Tethyan areas during the Oxfordian (Late Jurassic). Palaeogeography, Palaeoclimatology, Palaeoecology, 222, 10-32. Abstract: The paleobiogeographical distribution of Oxfordian ammonites and coral reefs in northern and Central Europe, the Mediterranean area, North and East Africa, and the Middle East and Central Asia is compared with the distribution in time and space of the most important lithofacies. Interest in the Oxfordian is focused on changes in facies and in biogeographical patterns that can be interpreted as the results of climatic events. Paleotemperature trends inferred from oxygen isotopes and paleoclimatic simulations are tested against fossil and facies data. A Late Callovian–Early Oxfordian crisis in carbonate production is indicated by the widespread absence of Lower Oxfordian reefal formations. There is a gap (hiatus) in deposition on epicontinental platforms, with Middle Oxfordian deposits resting paraconformably on Upper Callovian, while shales accumulated in adjacent intracratonic basins. Simultaneously, in Mediterranean Tethys, radiolarites accumulated in deep troughs while Rosso Ammonitico facies formed on pelagic swells. However, deposition on swells was also discontinuous with numerous gaps (hiatuses) and sequences that are much reduced in thickness. Middle Callovian deposits are generally overlain by Middle Oxfordian limestones. The dearth of carbonates is consistent with a cooling event lasting about 1 My. By the middle Oxfordian a warming, leading to “greenhouse” type conditions, is suggested on the basis of both biogeographical (mostly coral-reef distribution) and geochemical data. Carbonates spread onto an extensive European platform while radiolarites reached a maximum development in the Mediterranean Tethys. Two distinct latitudinal belts, with seemingly different accumulation regimes, are therefore inferred. Similar latitudinal belts were also present in the late Oxfordian, when carbonates were widespread. The distribution of reefal facies in the late Oxfordian–early Kimmeridgian fits relatively well with GCMs simulations that imply low rainfall in the Tethyan Mediterranean area and slightly higher precipitation in central and northern Europe. Local salinity variations, reflecting more arid or humid conditions, may bias the paleotemperature signal inferred from del 18 O values. Biogeographical and facies distributions, combined with del 18 O values, unravel the ambiguity and support a Late Callovian–Early Oxfordian cooling followed by warming in the later Oxfordian.
Chowdhury , A.N. 1980. Geochemistry and Sedimentology of the Corallian Sediments of Southern England. Unpublished Ph.D. Thesis, Geology Department, Faculty of Science, University of Southampton, 579 pp. By Ahad Newaz Chowdhury. [This is a particular good and large thesis]
Corallian rocks from outcrops on the Dorset coast, and from boreholes at Baulking and Uffington in Berkshire and from Warlingham in Surrey were subjected to petrographical, mineralogical and geochemical investigation. Pronounced mineral-variation exists between the studied localities: well-crystallised montmorillonite [smectite] shows highest concentrations in the Lower Calcareous Grit Group of Berkshire with reduced crystallinity and concentration in Dorset and at Warlingham, where it is subordinate to illite and kaolinite. In the Baulking and Uffington Boreholes authigenic zeolites of the clinoptilolite/heulandite type, low tridymite-crystobalite, euhedral biotite and apatite accompany the montmorillonite [smectite]. This association is thought to be genetically related, of volcanic origin, formed by the decomposition of air-fall ashes both on adjacent landmasses and in the area of deposition. Upward decrease in montmorillonite content suggests that volcanicity took place in the early phases of Corallian sedimentation. The volcanic phase seems to have been contemporaneous with the shoaling which initiated Corallian sedimentation in southern England suggesting a common tectonic control. The westward increase in montmorillonite content locate the volcanoes in this direction: Jurassic - early Cretaceous volcanic rocks reported from the South Western Approaches (Harrison et al. 1979) provide the probable source.
Geochemical investigation of 27 elements was mainly by X.R.F. analysis. Variation occurs both between localities and within localities, mostly reflecting clay mineral variation. Highest concentrations of most of the elements occur at Warlingham suggesting that element-concentration was mainly controlled by the detrital clays which dominate this area: upward increase in element concentration occurs in all three areas, implying an upward-increasing dominance of detrital clays and a lessening volcanic influence. A small group of elements (Cr, Mo, Ni, Pb, S, V, Zn) known to be associated with organic carbon, reach their maxima at the Dorset coast outcrops rather than Warlingham. This may result from an analytical artefact, sampling concentrating on mud rocks which are poorly represented at Warlingham. The differences between Dorset and Berkshire relate to the greater preservation of organic matter in in the former area, where reducing conditions prevailed: Berkshire samples show abundant signs of reworking and little of post-burial reducing conditions. The Upper Calcareous Grit is distinct from the lower Groups: it is enriched in various elements (Al, Fe, Ti, Mn, Ni, Pb, Cr, Cu, V, P, Ce, Y, As, Zn) attributable to intense chemical weathering during the protracted period of deposition (it spans three ammonite zones compared to two zones spanned collectively by the lower three Groups.
Corallian limestones are mostly shoal calcarenites and lagoonal micrites: calcirudites are few, thin and occur with calcarenites. Coral patch reefs are common in Berkshire. Bioturbation is widespread, leading at its most intense to rubbly limestones. The Corallian Limestones display the textures of phreatic diagenesis and lack signs of compaction indicating that each limestone unit was almost fully lithified before successive younger sediments were deposited. The variation. The variation in Sr-content from subreef oolite shoals to patch reefs in Berkshire is primarily related to permeability and diagenesis, including the relative timings of lithification of oolites and reefs. Post-reef exposure and uplift is indicated by the development of vuggy porosity in the Coral Rag. Exceptional concentrations of iron in the Red Beds of the Trigonia clavellata Beds of the Dorset coast is a consequence of penetration of iron-rich fresh waters from the Sandsfoot Clay, in the form of a phreatic lens. Geochemical studies confirm a lagoonal origin for the Sandsfoot Clay and further attest to the lagoon containing fresh water. Element concentrations vary with rock-type, Sr most notably.
Detailed analysis of the tectonic and depositional events of the Mesozoic Era reveals that the area of deposition consisted of fault-bounded blocks, each showing repetition of more or less similar tectonic and depositional events from at least Lower Jurassic times onwards. Groups of blocks associated to form persistently elevated Massifs or persistently subsiding troughs, the two usually separated by other groups of blocks called Shelves which tended to lie close to sea-level, either above or below, and subject to intermittent accumulation and loss of sediment. The Oxford Clay, which underlies Corallian rocks, is dominated by a detrital illite-kaolinite assemblage and denotes uniform marine conditions over both Troughs and Shelves. The Corallian rocks show sharp contrasts between clay-dominated Troughs and carbonate/quartz sand - dominated Shelves, with marked shoaling in the latter accompanied by evidence of volcanic activity to the west. Within the Shelves, individual fault-bounded blocks moved independently. For example the Berkshire Shoal covers the Oxford Block whereas deeper muddy environments occurred on the adjacent Aylesbury Block. Uplifts extended to the Massifs, particularly those in the west, which supplied abundant quartz sands and occasional pebble horizon. These detrital sands spread rapidly eastwards across adjacent shelves to lodge in the nearest Trough. They did not reach Warlingham nor the East Kent Shelf. Earlier authors have identified cycles of sedimentation, either three or four, but have never satisfactorily applied them in Kent. Tectonic uplifts generating pulses of detritus can readily explain these cycles, far better than eustatic movements of sea-level. These tectonic movements resulted in the release of silica-rich connate waters which encouraged abundant sponge populations in Dorset and along the Wheatley Fault which separate the Oxford and Aylesbury Blocks; they also caused local uplifts such as the one which elevated the Oxford Block after Coral Rag was deposited and one which warped the Winchester and Portsdown areas, preventing deposition of the Berkshire and Osmington Oolite Groups. A final tectonic movement downwarped the entire area and permitted deposition of the Kimmeridge Clay. [end of abstract]
Chowdhury, A. N. 1982a. Variations in diagenetic environments of the Coral Rag and underlying oolite of the Osmington Oolite Formation (Upper Oxfordian) of the Oxford - Berkshire area, U.K., and their implications. Sedimentary Geology, 32, 247-263.
Chowdhury, A.N. 1982b. Smectite, zeolite, biotite and apatite in the Corallian (Oxfordian) sediments of the Baulking area in Berkshire, England. Geological Magazine, 119, 487-496.
Coe , A.L. 1995. A comparison of the Oxfordian successions of Dorset, Oxfordshire and Yorkshire. In: Taylor, P.D. (ed.). Field Geology of the British Jurassic. Geological Society, London, 151-173.
Cope , J.C.W., Duff, K.L., Parsons, C.F., Torrens, H.S., Wimbledon, W.A., and Wright, J.K (editors). 1980. A Correlation of the Jurassic Rocks in the British Isles, Part 2: Middle and Upper Jurassic, Special Report No. 15 of the Geological Society of London, 109 pp. ISBN 0- 632-00714-1, paperback. Blackwell Scientific Publications, Oxford.
Corbett , P.W.M., Stromberg, S.G., Brenchley, P.J. and Geehan, G. 1994. Laminaset geometries in fine grained shallow marine sequences: core data from the Rannoch Formation (North Sea) and outcrop data from the Kennilworth Member (Utah, USA) and the Bencliff Grit (Dorset, UK). Sedimentology, 41, 729-745.
Abstract: Sandbodies from storm-dominated marine. and marginal marine environments commonly contain intervals of laminated fine sandstones: A characteristic of such lamination is the presence of low angle cross lamination. In order to model correctly the effects of such lamination on a waterfiood of an oil-bearing shoreface sequence it was necessary to quantify the geometry of the laminaset elements. This challenge has been greatly complicated by the lack of outcrop of the formation of interest. The Middle Jurassic Rannoch Formation of the North Sea only occurs in the subsurface where it is not possible in core to measure the aspect ratio of laminasets directly. In this study, the laminaset geometry data that can be obtained from core (e.g. apparent set thicknesses) were collected for the Rannoch Formation. These data were compared with similar data from potential outcrop analogues in (1) the Cretaceous Kennilworth Member of the Blackhawk Formation in Utah, USA and (2) the Upper Jurassic Bencliff Grit from the Dorset coast, UK. A quantitative analysis of laminaset geometries has been used to compare subsurface core with potential outcrop analogues. The Rannoch Formation core is characterized by numerous low angle truncations. We have measured these features in two wells (means of 7.20 and 12.10). Mean apparent set thicknesses were 0.24 and 0.19 m. In the outcrop sections studied. truncation angles ranged from 9.60 to 13.40 and mean set thicknesses from 0.24 to 0.34 m. Mean bounding surface dips of 5,8° and 8.6°. and mean laminaset lengths of 2.3 and 4.1 m .were also measured, directly in the field and by using photomosaics. On the basis of this comparison, the Kennilworth Member in Utah was found to be the most suitable and the geometries (i.e. aspect ratios) measured there were used to generate an appropriate geometry of Rannoch laminaset geometries for use in engineering studies: laminaset length, 2.0 m; laminaset thickness, 0.2 m.
Cosgrove , M.E. and Salter, D.L. 1966. The stratigraphical distribution of kaolinite in the post-Armorican of south-west England. Proceedings of the Ussher Society, 1, 249-252.
Cox , B.M. and Gallois, R.W. 1981. Stratigraphy of the Kimmeridge Clay of the Dorset type area and its correlation with some other Kimmeridgian sequences. Report of the Institute of Geological Sciences, No. 80/4, 144.
Robert Damon, 1814-1899, was a well-known Dorset geologist and collector of and dealer in fossils. He was born in Weymouth, with origins in a Flemish family. He ran a fossil shop at Augusta Place, the Esplanade, Weymouth. This shop is now a fish and chip shop (information kindly provided by his great, great grandaughter - Carole Burridge - nee Carole Damon, who lives in Bridport). Robert Damon was a Member of the Imperial Natural History Society of Moscow, and visited Russia in 1883, bringing back samples. His books are extremely interesting, with many diverse footnotes and sidelines. Robert Damon made a private collection of 400 Dorset fossils to illustrate his books. The Victoria Museum, Australia has ichthyosaurs from Damon, and many other museums contain fossils of his.
Damon , R. 1860. Handbook to the Geology of Weymouth and the Isle of Portland; with Notes on the Natural History of the Coast and Neighbourhood. By Robert Damon. Accompanied by a map of the district, geological sections, plates of fossils, coast views, and numerous other illustrations. London, Edward Stanton, 6 Charing Cross, 1860. This edition is available online in Google Book Search. The second edition, listed below is mostly the same but with some additions.
, R. 1884. Geology of Weymouth, Portland, and Coast of Dorsetshire, from Swanage to Bridport-on-the-Sea: with Natural History and Archaeological Notes. New and Enlarged Edition (2nd Ed.), Weymouth, R.F. Damon, London, Edward Stanford. 250p. With a colour geological map of part of the Dorset coast, and including a log of the Purbeck strata of Durlston Bay, Swanage, by H. W. Bristow and Prof. E. Forbes (although note that it contains a small error). (A copy of Damon's second edition is in the possession of Ian West)
Preface to Second Edition
Since the issue of the First Edition increased attention has been given to the Geology of the coast of Dorsetshire, especially in the contributions of Messrs. Blake and Hudleston, and Professor Prestwich, which in part have been embodied in the present volume.
Elementary and explanatory notes are given for the use of those young in the study of the science.
A description of the geological formations of Swanage and Bridport, the two extremes of the district under consideration, is for more convenient reference placed towards the end.
The Geological Survey of this district was almost entirely made by Mr. Henry W. Bristow, Senior Director of the Geological Survey of Great Britain. To him I am greatly indepted for a final revision of the work. Mr. W. Topley, of the Survey, has also kindly given much assistance, as have also Messrs. G. Sharman and E. T. Newton with the lists of fossils. Mr. Etheridge has favoured me with the Bridport portion of his unpublished sections of the Oolitic rocks of England.
The works I have consulted are necessarily very numerous, and to their respective authors I acknowledge my great obligations.
To the above and other friends, who have kindly responded to my enquiries for information, my sincere thanks are rendered.
Weymouth, October 1884.
Davidson , T. 1874-1882. Monograph of the British Fossil Brachiopoda. Vol. 4, Palaeontographical Society.
, G.M. 1935. The Dorset Coast. Adam and Charles Black, London (2nd Edition, 1956)
Delair , J.B. 1958. The Mesozoic reptiles of Dorset, Part 1. Proceedings of Dorset Natural History and Archaeological Society, vol. 79, pp. 47-72. (see also Part 2 and Part 3 - separate papers).
De Wet , C.B. 1998. Deciphering the sedimentological expression of tectonics, eustasy and climate. A basinwide study of the Corallian Formation, southern England. Journal of Sedimentary Research, 68, 653-667.
Donovan , D.T. and Stride, A.H. 1961. An acoustic survey of the sea floor south of Dorset and its geological interpretation. Philosophical Transactions of the Royal Society, Series B, 244, 299-330. Offshore outcrops of the Corallian.
Dorset Geologists' Association Group . 2003. Coast and Country: Geology Walks in and Around Dorset (including excursions within the World Heritage Site). Compiled by members of the Dorset Geologists' Association Group to celebrate 10 years of their existence 1993-2003. Published by the Dorset Geologists' Association Group 2003, ISBN 0-9544354-0-0, 208pp. Following an introduction by the late Professor Michael House, there are 28 field excursions given by different authors. Some individual excursion guides in this book may be referred to separately in these bibliographies. See Raggett for Osmington Mills.
Falcon , L.F. and Kent, P.E. 1960. Geological results of petroleum exporation in Britain 1945-1957. Geological Society of London, Memoir No. 2, 56 pp.
Folk , R.L. 1962. Spectral subdivision of limestone types. American Association of Petroleum Geologists, Memoir No. 1, 62-84.
Fursich , F.T. 1973. Thalassinoides and the origin of nodular limestones in the Corallian Beds (Upper Jurassic) of southern England. Neues Jahrb. Geol. Palaeont. Abhandlungen, 3, 136-156.
Fursich, F.T. 1974. Corallian (Upper Jurassic) trace fossils from England and Normandy. Stuttgarter Beitr. Naturk, B13, 1-52.
Fursich, F.T. 1975a. Trace fossils as environmental indicators in the Corallian of England and Normandy. Lethaia, 8, 151-172.
Fursich, F.T. 1976. The use of macroinvertebrate associations in interpreting Corallian (Upper Jurassic) environments. Palaeogeography, Palaeoclimatology, Palaeoecology, 20, 235-256.
Fursich, F.T. 1976. Fauna-substrate relationships in the Corallian of England and Normandy. Lethaia, 9, 343-356.
Fursich, F.T. 1977. Corallian (Upper Jurassic) marine benthic associations from England and Normandy. Palaeontology, 20, 337-385.
Fursich, F.T. 1978. Eustatic cycles in the Jurassic. Palaeogeography, Palaeoclimatology, Palaeoecology, 23, 1-32.
Goldring , R., Astin, T.R., Marshall, J.E.A., Gabbott, S. and Jenkins, C.D. 1998. Towards an integrated study of the depositional environment of the Bencliff Grit (Upper Jurassic) of Dorset. In: Underhill, J.R. 1998. Development, Evolution and Petroleum Geology of the Wessex Basin. Geological Society of London, Special Publication, No. 133, Geological Society Publishing House, Bath, 420 pp. ISBN 1-897799-99-3. Symposium of papers from a Petroleum Group Meeting of the Geological Society of London at Burlington House, Piccadilly from 27th to 28th June, 1985, convened by Dr John R. Underhill, Department of Geology, Edinburgh, Scotland.
Grieves , I.A.T. 1986. A Depositional Model for Part of the Corallian Sequence (Oxfordian), Dorset Coast. Unpublished M.Sc. Thesis. University of Reading.
Hathaway , E. 1994. Smuggler: John Rattenbury and his Adventures in Devon, Dorset and Cornwall 1778-1844. Shinglepicker Publications, Swanage. 199 pp. with an index and a short but useful bibliography. [Not geological, not specifically on Osmington Mills, but with reference to Weymouth, Portland, Swanage and particularly Beer in Devon. It provides much detail on smuggling operations because it is based on the memoirs of a smuggler published in 1837. ]
House , M.E. 1993 (and earlier edition in 1989). Geology of the Dorset Coast. Geologists Association Guide No. 22. 2nd edition, 164 pages plus plates. ISBN 0 7073 0485 7.
Howe, J.A. 1910. The Geology of Building Stones. Arnold's Geological Series. General Editor, Dr. J. E. Marr, F.R.S. By J. Allen Howe, B.Sc., F.G.S. London, Edward Arnold, 455 pp.
Hudson , J.D. 1982. Pyrite in ammonite-bearing shales from the Jurassic of England and Germany. Sedimentology, 29, 639-667.
Hudson, J.D. and Martill, D.M. 1991. The Lower Oxford Clay: production and preservation of organic matter in the Callovian (Jurassic) of central England. In Tyson R.V and Pearson, T.H. eds., Modern and Ancient Continental Shelf Anoxia. Geological Society Special Publications, 58, 363-379.
Kenig , F., Hayes, J.M., Popp, B.N. and Summons, R.E. 1994. Isotopic biogeochemistry of the Oxford Clay Formation (Jurassic), UK. Journal of the Geological Society, London, 151, 139-152.
Kent , P.E. 1985. U.K. onshore oil exploration, 1930-1964. Marine and Petroleum Geology, v 2(1), pp 56-64, 7 figs, 15.
Lees , G.M. and Cox, P.T. 1937. The geological basis for the search for oil in Great Britain by the D'Arcy Exploration Co. Ltd. Quarterly Journal of the Geological Society, London, 93, 156-190. Oil in the Bencliff Grit. Oil Seep at Bran Point.
Lord , A.R., Copestake, P., Boomer, I.D., Sheppard, L.M., Fuller, N.G., Clements, R.G., Bown, P.R., Riding, J.B., Batten, D.J., Lister, K.K. and MacLennen, A.M. 1987. Jurassic. Pp. 3-78. In: Mesozoic and Cenozoic Stratigraphical Micropalaeontology of the Dorset Coast and Isle of Wight, Southern England. British Micropalaeontological Society, Guide Book 1. Field Guide for the 20th European Micropalaeontological Colloquium. 183pp. [See pages 44-57 - listing of foraminifera, ostracods, calcareous nannofossils, palynomorphs (pollen, dinoflagellates and acritarchs); for Nothe Grit, Nothe Clay, Osmington Oolite, Trigonia clavellata beds etc.]
Morley , G. 1994. Smuggling in Hampshire and Dorset 1700 - 1850. Countryside Books, Newbury, Berkshire. 220 pp. First published 1983, reprinted 1984, 1985, 1987; revised and reprinted 1990, 1994. [Interesting non-geological book with chapters on the Isle of Purbeck, and on Weymouth, the West Dorset Coast, and Lyme Regis. With a glossary of smuggling terms and an index. See pp. 193-195 re Osmington Mills.]
Newell , A. J. 2000. Fault activity and sedimentation in a marine rift basin (Upper Jurassic, Wessex Basin, UK). Journal of the Geological Society, London, 157, 83-92. Abstract: Shallow-marine carbonates and siliciclastics of the Corallian Formation (Oxfordian - Early Kimmeridgian) accumulated on and around an intrabasinal high in the extensional Wessex Basin. Four sequences can be recognised. Sequences 1-3 accumulated under conditions of thermal subsidence on a ramp-type margin. The initial sequence was siliciclastic. Highstand sedimentation in this sequence reflects the supply of sandy mud from a recently emergent intrabasinal high. During transgression and regression this muddy sediment was reworked into cleaner sandstone bodies by landward or basinward migrating zones of shoreface erosion. Carbonates dominate the second and third sequences when rising sea-level increased the area of carbonate production and reduced siliciclastic input. Oolite bodies developed as both transgressive barrier bars and highstand sheets. The fourth sequence formed during the activation of major normal faults. This caused the breakdown of the ramp system and patterns of sediment accumulation were strongly controlled by tectonic subsidence patterns. [Discusses the Abbotsbury Ironstone as the result of sediment starvation at the time of maximum flooding.]
Norris , M.S. & Hallam, A. 1995. Facies variations across the Middle-Upper Jurassic boundary in western-Europe and the relationship to sea-level changes. Palaeogeography, Palaeoclimatology, Palaeoecology, 116, 189-245.
Page , K.N. 1994. A review of the suitability of key British Callovian-Oxfordian and Oxfordian Kimmeridgian sites as Global Stratotype sections and Points (GSSPs) for stage boundaries (Abstract). In (Atrops, F., ed.) Guide book and abstracts. 4th Oxfordian and Kimmeridgian Working Groups Meeting, Lyon, France, June 1994, 15-16.
Page, K.N., Melendez, G., Hart, M.B., Price, G.D., Wright, J.K., Bown, P. and Bello, J. 2006. Integrated stratigraphical study of the candidate Oxfordian Global Stratotype Section and Point (GSSP) at Redcliff Point, Weymouth, Dorset, UK. Volume 4, 7th International Congress on the Jurassic System, 200-201.
Pearce , C.R., Hesselbo, S.P. and Coe, A.L. 2005. The mid-Oxfordian (Late Jurassic) positive carbon-isotope excursion recognised from fossil wood in the British Isles. Palaeogeography, Palaeoclimatology, Palaeoecology, 221, Issues 3-4, 343-357. By Christopher R. Pearce, , Stephen P. Hesselbo, and Angela L. Coe. Abstract: The carbon-isotope ratios of fossil wood have recently been confirmed as a proxy for changes in the isotopic composition of palaeoatmospheres. Carbon-isotope data from fossil wood samples collected from the Jurassic (Oxfordian) Staffin Shale Formation on the Isle-of-Skye, Scotland (Boreal/Sub-Boreal ammonite zonation) reveal a long-term positive carbon-isotope excursion of at least 3‰. This excursion reaches a maximum in the mid-Oxfordian, and closely matches the carbon-isotope ratios previously reported from belemnites collected from the same section and carbon-isotope data from carbonates in other European sections. This confirms that the mid-Oxfordian positive carbon-isotope excursion affected the total exchangeable carbon reservoir. Fossilised wood samples collected at a higher stratigraphic resolution, but over a shorter interval from the Corallian Group in Dorset, England (antecedens, parandieri and cautisnigrae subzones; NW European ammonite zonation) show considerable scatter in their carbon-isotope ratios, and no trends are discernable. The combined Isle-of-Skye and Dorset dataset shows that the long-term Oxfordian positive carbon-isotope trend coincides with a long-term relative sea-level change, and that the most positive carbon-isotope ratios occur across the plicatilis–transversarium biozonal boundary (Sub-Mediterranean ammonite zonation). This implies that the carbon-isotope excursion was not caused by the well-documented rise in sea-level in the transversarium Zone. Although very low carbon-isotope ratios from fossil wood samples are recorded from the Nodular Rubble Member (parandieri Subzone) of Dorset, there is not a sufficiently coherent signal to ascribe these values to the gas–hydrate dissociation event previously hypothesized from the carbon-isotope ratios of Tethyan marine carbonates. A microscopal analysis of the charcoalified debris from the Staffin Shale Formation indicates a prevalence of the wood genus Cupressinoxylon [the Purbeck fossil tree, described in the papers of Jane Francis], derived from a cheirolepidiaceaen conifer.
Penn , I.E., Chadwick, R.A., Holloway, S., Roberts, G., Pharaoh, T.C., Allsop, J.M., Hulbert, A.G. & Burns, I.M. 1987. Principal features of the hydrocarbon prospectivity of the Wessex-Channel Basin, UK. Pp. 109-118 in Brooks, J. and Glennie, K., Petroleum Geology of North West Europe, Graham and Trotman, London. vol. 1, 598p + xxiii,
Perkins , J.W. 1977. Geology Explained in Dorset. David and Charles, Newton Abbott, 224 pp. ISBN 0 7153 7319 6.
Price, G. D. and Page, K.N. 2008. A carbon and oxygen isotopic analysis of mollusc an faunas from the Callovian-Oxfordian boundary at Redcliff Point, Weymouth, Dorset: implications for belemnite behaviour. By Gregory D. Price & Kevin N. Page. Proceedings of the Geologists' Association, 119, 153-160.
Abstract: Macrofossils (belemnites, Gryphaea and ammonites) from the Callovian-Oxfordian boundary at Redcliff Point, Weymouth, Dorset were examined using petrographic, isotopic and geochemical methods to investigate the environmental conditions within which they were formed. The belemnites (Hibolithes hastata), Gryphaea and ammonites (Cardioceras sp.) exhibit the petrographic and geochemical criteria for being well preserved. Values of 8180 for Gryphaea provide palaeotemperature ranges of c. 9.8-14.1 °C (mean 11.8 °C); belemnite palaeotemperature ranges of c. 1O.8-15.8°C (mean 12.8°C); and cardioceritid ammonites palaeotemperature ranges of c. 12.7-19.6°C (mean 15.4°C). The data define a predictable depth-related temperature gradient. The estimated range of palaeotemperatures derived from the belemnites straddle both Gryphaea and ammonite ranges. Hence, rather than being strictly nektobenthonic, belemnites may have migrated vertically within the water column in search of food, warmth, or for evasion from predators. The del 13C profile revealed is less clear and may result from either carbonate precipitated in reduced salinity surface waters characterized by more negative carbon isotopes than open-marine conditions or it may reflect the effects of non-equilibrium fractionation.
Raggett , G. 2003. Osmington Mills: excursion guide. Pp. 132-139 in: Dorset Geologists' Association Group. 2003. Coast and Country: Geology Walks in and Around Dorset (including excursions within the World Heritage Site). Compiled by members of the Dorset Geologists' Association Group to celebrate 10 years of their existence 1993-2003. Published by the Dorset Geologists' Association Group 2003, ISBN 0-9544354-0-0, 208pp.
Salfeld , H. 1917. Monographie der Gattung Ringsteadia gen. nov. Palaeontographica, 63, p. 69.
Scotchman , I.C. 1991. The geochemistry of concretions from the Kimmeridge Clay Formation of southern and eastern England. Sedimentology 38, 79-106. [Notes: Three types of nodules. - calcareous concretions, septarian calcareous concretions and pyrite/calcite concretions. Septarian - long history - early initiation, several phases of burial. Non-septarian concretions began growth in sulphate reduction zone. Pyrite/calcite concrets formed in sulphate-reduction to methanogenesis transition zone. Calcareous concretions form in swell areas and also in basin during low sedimentation rate. Pyrite/calcite concretions occur in organic rich mudstones deposited in basin under high sedimentation rates. Ferroan dolomite nodules grew under very high sedimentation rates. Curtis zones. Sulphate reduction known as SR zone, Methanogenesis is Me zone, decarboxylation zone is D zone. Due to lack of sulphate in the Me and D zone porewater carbonates are predominantly dolomitic. Nodule locations can be controlled by high organic matter horizons or biogenic carbonate. In fractures early brown cement and later white cement. Fibrous outer calcite is synchronous with septarian fracture infills. Burial history curves. Useful isotope data.]
Sellwood , B., Wilson, C. and West, I.M. 1990. Jurassic Sedimentological Congress, August 22-26th, 1990. Field Guide to Dorset and Yorkshire Coast. Leaders Bruce Sellwood and Chris Wilson. Assisted by Andy Clitheroe. 89 pp.
Selley , R. C. and Stoneley, R. 1987. Petroleum habitat in south Dorset. Pp. 139-148 in Brooks, J. and Glennie, K., Petroleum Geology of North West Europe, Graham and Trotman, London. vol. 1, 598p + xxiii.
Stoneley , R. and Selley, R.C. 1986. A Field Guide to the Petroleum Geology of the Wessex Basin. Imperial College, London, Geology Department.
Stockey , R.A. 1980. Jurassic araucarian cone from southern England. Palaeontology, 23 (3), 657-666. [An araucarian cone (monkey puzzle tree family) was found in presumably Corallian limestone at Black Head, similar to those of the Bunya tree of Queensland. This is interesting evidence that such a tree once lived in the Northern Hemisphere.]
Strahan , A. 1898. The Geology of the Isle of Purbeck and Weymouth. Memoirs of the Geological Survey, England and Wales. 278pp. with coloured map and sections. Printed for Her Majesty's Stationery Office by Wyman and Sons, Ltd., Fetter Lane, E.C. London. By Aubrey Strahan, M.A., F.G.S.
Stow , D.A.V. 2005. Sedimentary Rocks in the Field: A Colour Guide. Manson Publishing, London, 320pp. By Professor Dorrik Stow, School of Ocean and Earth Science, National Oceanography Centre, Southampton University.
The world of sediments and sedimentary rocks is exciting and dynamic. It is fundamental to our understanding of the whole Earth System and of the wide range of environments that characterize its surface. It also provides the key to a plethora of natural resources - industrial, chemical, metallic, water, and energy resources - that shape the way we live.
Ideas and concepts in sedimentology are fast changing, but fundamental fieldwork and data collection remain at its heart. In the first instance, it is an observational science, closely followed by laboratory, experimental, and theoretical work. The primary skill lies in knowing how and what to observe and record in the field, and then how best to interpret these data. For me, this has always been a distinctly visual process. The unique aspect of this guide, therefore, is in the wide range of graphic material that draws together the very latest ideas and interpretations (over 50 line drawings), coupled with over 425 photographs (from 30 differentcountries) of the principal types of sedimentary rocks and their characteristic features. It is intended for ease of field use by students, professionals, and amateurs alike.
All the field photographs illustrated have been carefully selected from my own collection, except where otherwise acknowledged. All figures have been redrawn and many specially compiled from the latest research knowledge, always with a view to providing the best aid to recognition, classification, and interpretation in the field. The key emphasis is to help with field observation and recognition of the main features of sedimentary rocks. Some pointers are given towards their preliminary interpretation, but further endeavour in this area must remain the province of the broader sedimentological literature, and will depend on the nature of the work in progress. Many different disciplines and sub-disciplines of geology and oceanography, as well as sedimentology, require a field understanding of sediments and sedimentary rocks. They include: geophysics and geochemistry, paleontology and Quaternary geology, physical geography and soil science, archeology and environmental science. Above all, and for all, this is a book to take into the field and use!
Sun , S.Q. 1989. A new interpretation of the Corallian cycles of the Dorset coast. Geological Journal, 24, 139-158.
Sun, S.Q. 1990. Facies related diagenesis in a cyclic shallow marine sequence: the Corallian Group (Upper Jurassic) of the Dorset coast, southern England. Journal of Sedimentary Petrology, 60, 42-52.
Sun, S.Q. 1990. Discussion on swaley cross-stratification produced by unidirectional flow, Bencliff Grit (Upper Jurassic), Dorset. UK. Journal of the Geological Society, London, 147, 396-400.
Sun, S.Q. 1990. Sedimentation, diagenesis and reservoir evaluation of the Corallian (Upper Jurassic) Group, southern England. Unpublished Ph.D. Thesis, University of Reading.
Taitt, A. H. and Kent, P.E. 1939. Note on an examination of the Poxwell Anticline, Dorset. Geological Magazine, vol. 76, pp. 173-181.
The discovery of an active oil seepage in Corallian sandstones at Osmington Mills, near Weymouth, led in 1937 to an examination of the adjacent Poxwell or Moigns Anticline by geologists of the D'Arcy Exploration Company, a subsidiary of the Anglo-Iranian Oil Company, Ltd. [now well-known under its modern name - "BP"]. The investigations, carried out by Dr. C.T. Barber in the earliest stages, and subsequently by the junior author, consisted of surface mapping assisted by pits, trenches, auger holes, and shallow bore-holes, and culminated in the drilling of a test well in the crestal area of the anticline. This note summarises the more important information obtained with regard to stratigraphy and tectonics.
The general form of the Poxwell Anticline, which was ably described by Strahan (1898), is a dome, greatly elongated in an east-west direction, separated in the west by a small saddle from the larger Sutton-Poyntz anticline. In order to locate a bore-borehole to test the oil-producing possibilities of the Corallian it was, however, necessary to obtain informtion concerning the Ridgeway fault, which separates the the Jurassic and Cretaceous rocks on the northern flank of the structure.
Three shallow bore-holes were drilled along a north-south line across the presumed trace of the fault near Poxwell village. The most northerly borehole (lat. 50 degrees, 39 minutes, 14.3 seconds N, long. 2 degrees, 21 minutes, 52 seconds W.) penetrated 120 feet of Chalk, of which the lowest 22 feet was of the Micraster cortestudinarium Zone. A bore-hole 120 feet south of this, 40 feet deep, drilled through 20 feet of Chalk and Purbeck Limestone debris before encountering solid Chalk of the Rhynchonella cuvieri Zone. No. 3 bore-hole, 166 feet farther south, started in Purbeck and entered the Portland Sand at 171 feet, and at 230 feet the Upper Greensand, in which formation the well was completed at a depth of 432 feet (Fig. 2).
The true thicknesses, allowing for dip of the formations encountered in No. 3 borehole were Purbeck [but not complete Purbeck sequence] 80 feet [24 metres], Portland Stone 40 feet [12 metres], Portland Sand 42 feet [13 m.], and Upper Greensand c. 100 feet [c. 30m.].
The thickness of the Portland Stone, obtained by allowing for the dip of 42 degrees, shown in the cores of the Purbeck, proved to be less than anticipated. Dr. Arkell suggested that the apparent attenuation might be the result of normal faulting, but augering over the mapped Portland Stone outcrop on both flanks of the anticline showed that the recorded outcrop was too wide. The amended boundaries agreed with an approximate thickness of 40 feet for the Portland Stone.
In the light of the evidence obtained in the three shallow boreholes a location was chosen (lat. 50 degrees, 39 minutes, 4.7 seconds N., long. 2 degrees, 21 minutes, 23 seconds W.), with the object of penetrating the Corallian in the crestal area of the anticline and on the upthrow side of the Ridgeway Fault. Drilling was commenced on 24th May 1937, and completed at a depth of 1,666 feet [508 m.] two months later.
The following is a brief account of the formations penetrated in the Poxwell deep borehole.
Portland Beds: True thickness: 162 feet [49m.] in the borehole, 152 ft [46m.] true thickness.
Portland Stone. Soft buff limestone with rare chert bands. 0 to 28ft [8.5m] in borehole [not normal to the strata].
Portland Sand. Dark grey sandy clay and argillaceous sandstone. 28 - 160 ft in bh.
Kimmeridge Clay: 842 ft in borehole [247m]. True thickness: 700 ft [213m.] [conversion: 0.83]
Dark calcareous clays, rather silty in the upper part. 160 - 485 feet [325 feet, 99m.] in borehole, not at right-angles to the strata. [true thickness conversion: 82m. thick].
Oil shale with Saccomoma [Kimmeridge Blackstone] - depth in the borehole (oblique to bedding) 485-490 ft. [Thickness along borehole 5 ft or 1.5m, corrected to true thickness 1.26m. This is probably too thick for the Blackstone itself, about 60cm at Kimmeridge in the basin, and may include adjacent oil shale.]
Dark grey calcareous clays; abundant Aulacostephanus [Lower Kimmeridge Clay ammonite] in cores between 590 [180m] and 600 feet 183m.] in the borehole; Aulacostephanus with Amoeboceras and Aptychi between 750 [229m.] and 770 ft [235m.] in the borehole; Rasenia [ammonite from near the base of the Kimmeridge Clay] at 890 ft. [271m.] in the borehole, and Ostrea fragments [presumably the flat oyster Liostrea delta of the basal Kimmeridge Clay] below 965 ft [294m.]. Depths 490 - 1002 ft [149m - 305m in borehole, [apparent thickness in borehole - 185m, converted to vertical thickness 151m.]
Corallian Beds. 305 ft drilled. True thickness: 245 feet [75m.]
Ringstead and Sandsfoot Beds.
Brown and dark green sandy clay with scattered ironshot ooliths. 1002-1067 ft in the borehole. [not corrected for angular difference]
Rich oolitic ironstone [like the Abbotsbury Ironstone] with Chlamys midas. 1067 - 1075 ft in borehole. i.e. 8 ft in the borehole. Corrected - 6.4 ft = 1.95 m. [almost 2m of oolitic iron ore, an unusual feature, not seen on the coast at Ringstead].
Oolite of calcareous ooliths in a dark green matrix. 1075-1090 feet in borehole.
Trigonia clavellata Beds.
Hard grey crystalline limestone with abundant Trigonia and bands of marl and sandstone. 1090-1101 ft in the borehole. 1090-1101 ft in borehole.
Osmington Oolite Series.
Pale nodular limestone and dark clay ("Nodular rubble" [sponge spicule beds]). 1101-1117 in borehole.
Nodular oolitic limestone and marl. 1119-1142 ft in bh.
Light oolitic limestone. 1142-1152 ft in bh.
Dark grey oolitic marl with oolitic limestone nodules and pisolite. 1152-1176 ft in bh.
Soft grey sandstone and marly sandstone [notice not yellow underground and unoxidised]. 1176 - 1200 in bh. 24 ft in bh = 7.3m. Corrected 5.8m. vertical thickness approx.
Dark grey silty clay with Trigonia hudlestoni. 1200 - 1238 ft in bh.
Trigonia hudlestoni Bed
Oolitic limestone with abundant Chlamys fibrosa, Pleuromya sp. and Gryphaea sp. 1238-1256 ft in bh.
Calcareous sandstones and sandy limestones with large Gryphaea sp. and Cercomya undulata. 1256-1307 ft. in bh.
223 ft in borehole. True thickness 185 ft [56m.]
Dull grey silty clay with Cardioceras sp. at 1320 ft. and again at 1445 ft.
Great Oolite Series - 136ft drilled.
Forest Marble - 74 ft. drilled.
Hard light grey raggy limestone with Chlamys sp. 1530-1535.5 ft. in bh.
Hard grey-green marl with conchoidal fracture. Rare small Rhynchonella sp. in the lower part. 1535.5 - 1602.5 ft in bh.
Hard grey green marl with conchoidal fracture. Rare small Rhynchonella sp. in the lower part. 1535.5 - 1602.5 ft in bh.
Grey marl and limestone with abundant Goniorhynchia boueti, Ornithella cf. digona and Chlamys sp.
Fuller's Earth. 62 ft [18.9m.] drilled.
Hard light grey marl with limestone nodules. 1604-1612 ft in bh.
Hard light grey marl with conchoidal fracture, with scattered plant fragments and Oppelia fusca at 1646ft. 1612-1666. [end of borehole log]
[This is interesting in showing a very well-developed oolitic facies in the upper part. There is a rich oolitic iron ore with Chlamys midas in the Ringstead and Sandsfoot Beds. This is of Abbotsbury Ironstone facies, but within the Corallian not the Kimmeridge Clay. Another interesting aspect is the presence of green material, probably berthierine in the iron-rich Ringstea and Sandsfoot Beds. All this is suprising in view of the proximity to the coast section at Osmington Mills.]
[The subdivisions of the Corallian sequence are given as top and bottom depths in a borehole that is inclined in relation to bedding, and the figures are in feet. Therefore they need conversion before they become useful in comparision with the Osmington Mills coast section.]
[The paper continues for three more pages of text and one diagram. These further details are not reproduced here, but the short paper is in a well-known journal and probably very easily obtainable.]
[Of interest is mention of the early recognition by Lees and Cox of the thick Triassic salt sequence beneath the Poxwell area. This was understood even though it was not penetrated in the borehole. Here is a short extract from p. 180.]
There are a number of points of interest about this succession. The Kimmeridge Clay shows marked attenuation as compared with the standard succession at Kimmeridge, so that the Gravesia and Subplanites zones [i.e. Pectinatites Zones](from the "Blackstone" oil shale to the highest Aulacostephanus) measure less than 100 ft [30m.], as compared to 210 ft. [64m.] in the type section.
The unexpected development of Oolite and Oolitic Ironstone in the upper part of the Corallian is comparable with the facies at Abbotsbury, but the Ironstone here occurs at a lower horizon. The remainder of the Corallian is, as would be expected, closely similar to the outcropping beds at the well-known Osmington Mills sectin, 1 and a half miles distant. The Nothe Beds yielded a specimen of the lamellibranch Cercomya undulata, which was interesting in showing punctation, a feature usual in France, but previously unrecorded in England.
The beds below the Corallian were greatly reduced in thickness or absent. [continues]
Talbot , M.R. 1973. Major sedimentary cycles in the Corallian beds (Oxfordian) of southern England. Palaeogeography, Palaeoclimatology, Palaeoecology, 14, 293-317.
Talbot, M.R. 1974. Ironstones in the Upper Oxfordian of southern England. Sedimentology, 21, 433-450.
Tanner , L. 1993. Calcite veining in the corallian of Dorset: its tectonic and diagenetic implications. Unpublished B.Sc. Undergraduate Project, Department of Geology, University of Southampton, 63 pp.
Thomas , J. and Ensom, P. 1989. Bibliography and Index of Dorset Geology. Dorset Natural History and Archaeological Society, Dorchester, Dorset, 102p. See Corallian and Osmington references. See also the internet version.
Todd , J.E. 1903. Concretions and their geological effects. Bulletin of the Geological Society of America, 14, 353-356. [Not specifically on the Corallian, but a significant and under-used paper sensibly explaining features of nodular concretions, such as seen in the Corallian, the Kimmeridge Clay and other formations.]
Tyson , R.V., Wilson, R.C.L. and Downie, C. 1979. A stratified water column environmental model for the type Kimmeridge Clay. Nature, 277, 377380.
Underhill , J.R. 1998. Development, Evolution and Petroleum Geology of the Wessex Basin. Geological Society of London, Special Publication, No. 133, Geological Society Publishing House, Bath, 420 pp. ISBN 1-897799-99-3. Symposium of papers from a Petroleum Group Meeting of the Geological Society of London at Burlington House, Piccadilly from 27th to 28th June, 1985, convened by Dr John R. Underhill, Department of Geology, Edinburgh University, Scotland.
West , I.M. 1973. Carbonate cementation of some Pleistocene temperate marine sediments. Sedimentology, 20, 229-249. [No specific reference to the Corallian. Included only because of mention of poikilotopic calcite cements as in the Bencliff Grit.]
West, I.M. 1993. Natural hydrocarbon seepages and surface oil impregnations of the Wessex Basin: A review. Unpublished report of the Geology Department, Southampton University. [This briefly reviews the Dorset oil and gas seepages from east to west, mostly from the literature. Seepages include those of Osmington Mills.]
Wethered , E.B. 1889. The microscopic structure of the Jurassic pisolite. Geological Magazine, 7, 196-200.
Williams , M.E. 2003. The development of hiatal surfaces in the Osmington Mills Ironstone Member of the Upper Jurassic Ringstead Formation of south Dorset, England. Proceedings of the Geologists' Association, London, 114, No. 3, pp. 193-210. Abstract: The Osmington Mills Ironstone Member, a Corallian hiatal-condensed bed, contains a varied, mainly in situ fauna. It developed over a relatively short time (less than 0.33 Ma) and is part of a transgressive systems tract. A sharp deepening in sea-level, which has not been previously identified, marks its base; its top, the Oxfordian–Kimmeridge boundary, is a recognized maximum flooding surface. Although it is the only Corallian bed in south Dorset that contains corals, it comprises ooidal ironstone in places. Replacement of corals by ooidal ironstone indicates how the local depositional environment changed and explains lateral variation in the unit. Hiatal surfaces in the unit formed in different ways. Firm grounds and increased bioturbation record surfaces developed over the shortest time. Coral masses that have been modified by biomechanical processes indicate hiatal surfaces formed over longer periods. Reworked bioclasts and mixed fossil assemblages mark longer hiatuses. Early near-surface diagenesis, resulting in formation of berthierine, apatite and siderite, indicates hiatal surfaces formed over the longest time. Fundamental processes controlling bioturbation, destructive taphonomic patterns and early diagenetic mineralization interact with each other during the formation of hiatal surfaces. Integrated approaches to the identification and analysis of hiatal surfaces will help to unlock their potential use in sequence stratigraphy.
Wilson , R.C.L. 1965. The Petrology of Certain English Jurassic Limestones and Associated Sediments. Unpublished Ph.D. Thesis, University of Sheffield, Sheffield, 230 pp.
Wilson, R.C.L. 1966. Silica diagenesis in Upper Jurassic limestones of southern England. Journal of Sedimentary Petrology, 36, 1036-1049. Abstract: Silica diagenetic fabrics occurring in the Portland and Corallian Beds of southern England are described. On the basis of their morphology, five major fabric types are distinguished: mosaic quartz, chalcedonic overlays, spherulitic chalcedony, lutecite, and microcrystalline granular quartz. Of these, the first three may be cementation fabrics, and all except chalcedonic overlays may exhibit replacement features. The silica fabrics are dated according to their relation to carbonate diagenetic fabrics. Two major stages of silicification are demonstrated, the first being pre-calcite cement fabrics and the second post-calcite cement fabrics; each was probably accompanied by calcitization of sponge spicules. The latter occur in sufficient quantities throughout the sediments to account for the silica fabrics. Lack of silicification in the Corallian Beds, despite their high spicule content, is probably caused by calcite cements effectively reducing porosity early in their diagenetic history. This contrasts with the extensive development of cherts in the Portland Beds, in which high porosities are maintained after deposition to the present day.
Wilson, R.C.L. 1967. Diagenetic carbonate fabric variations in Jurassic limestones of southern England. Proceedings of the Geologists' Association, 78, 535-554.
Wilson, R.C.L. 1968a. Carbonate facies variation within the Osmington Oolite Series in southern England. Palaeogeography, Palaeoclimatology, Palaeoecology, 4, 89-123.
The Osmington Oolite Series of 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 only a very short period of 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) 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) Oolite Freestone Facies. This facies is dominated by rounded lumps derived from the Coral Limestones to the north and contains large (15m thick) accretion sets.
(3) Coral Limestone Facies. These sediments accumulated in a coral patch reef environment, in which formed coral biolithites and coral debris biomicrites.
Wheatley Limestone Facies. This facies consists of fine skeletal debris, largely micritised that was swept northwestward off the reef area.
Phyllosilicate Clay Facies. These sediments formed in 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.
Wilson, R.C.L. 1968b. Upper Oxfordian palaeogeography of southern England. Palaeogeography, Palaeoclimatology, Palaeoecology, 4, 5-28.
Wilson, R.C.L. 1980. Changing Sea-Levels: a Jurassic Case Study. Open University Press, 120pp.
Woodward , H.B. 1895. The Jurassic Rocks of Britain, vol. 5. Memoirs of the Geological Survey of England and Wales.
Wright , J.K. 1980. Oxfordian Correlation Chart. In: A Correlation of the Jurassic Rocks in the British Isles, Part 2: Middle and Upper Jurassic, edited by Cope, J.C.W., Duff, K.L., Parsons, C.F., Torrens, H.S., Wimbledon, W.A., and Wright, J.K., Special Report No. 15 of the Geological Society of London, 109 pp.
Wright, J.K. 1981. The Corallian rocks of north Dorset. Proceedings of the Geologists' Association, 92, 17-32.
Wright, J.K. 1986. The Upper Oxford Clay at Furzey Cliff, Dorset: stratigraphy, paleoenvironment and ammonite fauna. Proceedings of the Geologists' Association, 97, 221-228.
Wright, J.K. 1986. A new look at the stratigraphy, sedimentology and ammonite fauna of the Corallian Group (Oxfordian) of south Dorset. Proceedings of the Geologists' Association, 97, 1-21.
Wright, J.K. 1996. Perisphinctid ammonites of the Upper Calcareous Grit (Upper Oxfordian) of North Yorkshire. Palaeontology, 39, 433-469. [This is mostly, as the title suggests, on Yorkshire perisphinctids but the Spaunton Sandstone contains Osmington species (see p. 464). The reference list gives important relevant palaeontological publications on strata of this age in other countries, and is useful for the palaeontological specialist. These papers are generally not listed here.]
Wright, J.K. 2009. Osmington. Extract from Geological Conservation Review, vol. 21: British Upper Jurassic Stratigraphy (Oxfordian to Kimmeridgian), Chapter 2: Upper Jurassic Stratigraphy from Dorset to Oxford. Site Osmington (GCR ID: 910). OS Grid Reference: SY697816 - SY752813. Online pdf file:
Osmington by J.K.Wright. (text with diagrams but without photographs).
Introduction: The Oxford Clay Formation (Weymouth Member) and the Corallian Group are exposed in cliff and foreshore exposures for 5 km from Bowleaze Cove eastwards to Ringstead Bay (Figure 2.5). These exposures are the standard for the Oxfordian Stage in southern Britain, and constitute a site of international importance. A near-complete Lower and Middle Oxfordian succession is available, and the Upper Oxfordian is well developed, though having substantial gaps in the succession owing to intraformational erosion. The section has both stratigraphical and historical interest; it includes the type localities for several stratigraphical units, and has produced the type and figured specimens of many fossil species.
The geological prominence of the Osmington exposures first became apparent in the early 19th century when the site was described by Adam Sedgwick (1826). Both Fitton (1827) and Buckland and De la Beche (1836) later provided brief accounts. The first full descriptions of the stratigraphy were those given by Blake and Hudleston (1877, pp. 262–72), Damon (1884, pp. 22, 29, 38–46, plus map) and Woodward (1895, pp. 82–8). Woodward's account was based largely on the work of Blake and Hudleston (1877), these latter authors providing the most complete descriptions of the site in the 19th century.
Buckman (1923–1925, pp. 63–5) described the succession at the site, introducing several new stratigraphical terms, and figuring ammonites collected here. However, it was Arkell's classic studies of the rich bivalve and ammonite faunas (1929–1937, pp. 387–92 with distribution table and 1935–1948, pp. 66–7, 385–6 (lists of figured and cited specimens from the Dorset coast)) that best emphasize the key role played by this site in the studies of Oxfordian geology. Furthermore, Arkell's classic memoir on the geology of south Dorset (Arkell, 1947a), which describes the Osmington site in detail, is still in print some 60 years after it was written.
Wright, J.K. 2011. The ammonite faunas of the Osmington Oolite Formation (Jurassic, Middle Oxfordian) of the Dorset coast. Proceedings of the Geologists' Association, vol. 122, Issue 3, pp. 484-491.
A detailed study of the lithologies of each of the beds present in the Osmington Oolite Formation of south Dorset is used to allocate numerous loose-collected ammonites to their correct stratigraphic horizons. Much new material has been collected by the author in addition to the limited amount of material available in museum collections. The age of the faunas of the three constituent members of the Osmington Oolite Formation is each assessed and placed into the context of Middle Oxfordian ammonite sequences elsewhere in England and in Europe.
Ziegler , B. 1962. Die Ammonitengattung in Oberjura (Taxonomie, Stratigraphie, Biologie). Palaeontographica, A119, pp. 1-172.
To continue the Osmington Corallian Field Guide go to the section of interest:
- Osmington - Pt. 1 - Osmington Mills Introduction
- Osmington - Pt. 2 - Osmington Mills to Ringstead.
- Osmington - Pt. 3 - Bencliff Grit
- Osmington - Pt. 4 - Osmington Oolite
- Osmington - Pt. 5 - Black Head
- Osmington - Pt. 6 - Corallian Fossils
- Osmington - Pt. 7 - Bibliography
- Portland Harbour - Corallian
© 2013 Ian West, Tonya Loades, Catherine West and Joanna Bentley. All rights reserved. This is a purely academic website and images and text may not be copied for publication or for use on other webpages or for any commercial activity. A reasonable number of images and text may be used for non-commercial academic purposes, including field trip handouts, lectures, student projects, dissertations etc, providing source is acknowledged.
Geological fieldwork involves some level of risk, which can be reduced by knowledge, experience and appropriate safety precautions. Persons undertaking field work should assess the risk, as far as possible, in accordance with weather, conditions on the day and the type of persons involved. In providing field guides on the Internet no person is advised here to undertake geological field work in any way that might involve them in unreasonable risk from cliffs, ledges, rocks, sea or other causes. Not all places need be visited and the descriptions and photographs here can be used as an alternative to visiting. Individuals and leaders should take appropriate safety precautions, and in bad conditions be prepared to cancel part or all of the field trip if necessary. Permission should be sought for entry into private land and no damage should take place. Attention should be paid to weather warnings, local warnings and danger signs. No liability for death, injury, damage to, or loss of property in connection with a field trip is accepted by providing these websites of geological information. Discussion of geological and geomorphological features, coast erosion, coastal retreat, storm surges etc are given here for academic and educational purposes only. They are not intended for assessment of risk to property or to life. No liability is accepted if this website is used beyond its academic purposes in attempting to determine measures of risk to life or property.
Disclaimer: Geological fieldwork involves some level of risk, which can be reduced by knowledge, experience and appropriate safety precautions. Persons undertaking field work should assess the risk, as far as possible, in accordance with weather, conditions on the day and the type of persons involved. In providing field guides on the Internet no person is advised here to undertake geological field work in any way that might involve them in unreasonable risk from cliffs, ledges, rocks, sea or other causes. Not all places need be visited and the descriptions and photographs here can be used as an alternative to visiting. Individuals and leaders should take appropriate safety precautions, and in bad conditions be prepared to cancel part or all of the field trip if necessary. Permission should be sought for entry into private land and no damage should take place. Attention should be paid to weather warnings, local warnings and danger signs. No liability for death, injury, damage to, or loss of property in connection with a field trip is accepted by providing these websites of geological information. Discussion of geological and geomorphological features, coast erosion, coastal retreat, storm surges etc are given here for academic and educational purposes only. They are not intended for assessment of risk to property or to life. No liability is accepted if this website is used beyond its academic purposes in attempting to determine measures of risk to life or property.
Webpage - written and produced by:
Ian West, M.Sc. Ph.D. F.G.S.