Crinoid localities of the Devonian of the British Isles     

Stephen K. Donovan  Fiona E. Fearnhead 《Geology Today》2020,36(3):113-119

Who collects the Devonian crinoids of south-west England? Since the nineteenth century, almost nobody. Few palaeontologists pursue these fossils, undoubtedly handsome in life, but indifferently preserved. Herein, we make a survey of four of the most important crinoid sites, all of which have the potential to produce new specimens.  相似文献   

A quantitative analysis of the prototype [WCL] star CPD-56° 8032     

Paul A. Crowther  Orsola De Marco  M. J. Barlow  P. J. Storey 《Astrophysics and Space Science》1996,238(1):119-123

We present a detailed, quantitative study of the standard [WC10] Wolf-Rayet central star CPD-56^o 8032 based on new high resolution AAT UCLES observations and the Hillier (1990) WR standard model. Our analysis of CPD-56^o 8032 gives the wind properties (T _*=34500K, lg (L/L )=3.8, lg (M/M a^–1)=–5.4,v =225 km s^–1) and chemistry (C/He=0.5, O/He=0.1, by number), the latter suggesting an intimate relationship with the Ovi PN central stars and the PG 1159-035 objects. A comparison between the wind properties of CPD-56^o 8032 and Sk-66^o 40 (WN 10) indicates that low excitation, low wind velocity WR winds are common to both low mass PN central stars (WC sequence) and high mass post-LBV's (WN sequence).  相似文献   

Design of backfilled thin-seam coal pillars using earth pressure theory     

James G. Donovan  Mario G. Karfakis 《Geotechnical and Geological Engineering》2004,22(4):627-642

In underground coal mining any increase in coal recovery rate is dependent on a decrease in pillar size. Backfilling is one way of reducing the required size of pillars and hence the volume of coal left underground. Therefore any comparisons made between a self-supported mine layout and backfill supported mine layout are based directly on pillar design. The most effective way to examine the effect of backfill on pillar support, and subsequently the rate of recovery, would be to incorporate the mechanisms of backfill support directly into the current design procedure for coal pillars. This paper presents a review of the mechanics of backfill support, a method of estimating the magnitude of that support based on earth pressure theory, and an example that incorporates backfill support into current coal pillar design.  相似文献   

The Upper Pliocene Bowden shell beds,southeast Jamaica     

Stephen K. Donovan  Ron K. Pickerill  David G. Keighley 《Geology Today》2014,30(6):232-238

The Neogene fossil record of the Antilles is particularly rich and can satisfy the interests of most collectors, from foraminifers to vertebrates. The molluscs are among the commonest and most diverse groups, being found in both terrestrial and marine deposits. The Pliocene Bowden shell beds of southeast Jamaica, best known for its hundreds of species of molluscs, also yields diverse members of other groups, the total exceeding 800 species from a mere 5 m of stratigraphical section.  相似文献   

The Pebbles on the Beach: A Spotter’s Guide by Clarence Ellis,new edition,Faber & Faber,London (2018). xiii+218 pp., Pbk., ISBN: 978-0-571-34793-3. £9.99     

Stephen K. Donovan 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(6):798-799

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Anthropocene: A Very Short Introduction,Erle C. Ellis,Oxford University Press,Oxford (2018). xxii+183 pp., Pbk., ISBN: 978-0-19-879298-7. £7.99.     

Stephen K. Donovan 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(5):693

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Fossils of Folkestone,Kent, Philip Hadland,Siri Scientific Press,Manchester (2018). 148 pp., Pbk,ISBN: 978-0-9957496-5-8, £15.00     

Stephen K. Donovan 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(4):581

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Reading the Rocks: How Victorian Geologists Discovered the Secret of Life,Brenda Maddox,Bloomsbury, London (2017), xii+254 pp., Hbk., ISBN: 978-1-4088-7958-0. UK£20.00     

Stephen K. Donovan 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(1):92

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Two intriguing pluricolumnals (Crinoidea) from the Lower Palaeozoic of Powys and Shropshire     

Stephen K. Donovan  Anthony Butcher 《Proceedings of the Geologists' Association. Geologists' Association》2021,132(2):170-173

Complete fossils must be preferred to fragments for most palaeontological studies, but disarticulated specimens are nonetheless potential sources of noteworthy data. Two crinoid pluricolumnals are recorded from the lower Palaeozoic; informed discussion shows each is a basis for palaeobiological interpretation. Both are gracile and are probably belong to disparids. Floricrinus (col.) sp. is from the Silurian of Wenlock Edge, Shropshire, either from the Much Wenlock Limestone Formation (Wenlock) or, more likely, the Lower Elton Formation (Ludlow). This is the first crinoid from the Silurian of the British Isles with a pentapetaloid arrangement of the areola, a geometry common in the Middle-Upper Ordovician and higher in the geologic column. Pluricolumnal gen. et sp. indet. is from the Lower Llanvirn of Powys. One end of the otherwise straight specimen is tightly coiled. This is likely the proxistele, the most flexible region of the column, and the coiling occurred after the crown was lost by autotomy in response to an environmental disturbance.  相似文献   

Louis Leakey and Piltdown Man     

S. Kenneth Donovan 《Proceedings of the Geologists' Association. Geologists' Association》2021,132(3):405-406

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