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VOLUME 15 PART 3 JULY 2002 East Midlands Geological Society Contents President Vice-President Mercian News 150 Tony Morris Dr Richard Hamblin The Record Geobrowser Secretary Treasurer From the Archives Alan Filmer Mrs Christine Moore Bill Sarjeant 1935-2002 Editorial Board Dr Tony Waltham Tony Morris Book Reviews 156 Dr John Carney Mrs Judy Rigby Dr Andy Howard Mrs Judy Small Ian Jefferson, Mike Rosenbaum, Ian Smalley 157 Mercia Mudstone as a Triassic Council aeolian desert sediment Dr Beris Cox Janet Slatter Jack Brown Dr Ian Sutton Miss Lesley Dunn Neil Turner Trevor D. Ford 163 Dr Peter Gutteridge Dr Alf Whittaker Dolomitization of the Carboniferous Limestone Dr Andy Howard John Wolff of the Peak District: a review Mrs Sue Miles Jonathan D. Radley 171 Address for Correspondence The late Triassic and early Jurassic succession The Secretary, E.M.G.S. at Southam Cement Works, Warwickshire Rose Cottage, Chapel Lane, Epperstone, Nottingham NG14 6AE Reports 175 0115 966 3854 [email protected] Edgehill Quarry – Jonathan Radley Haute Provence – Alan Filmer The Mercian Geologist is published by the East Wieliczka Salt Mine – Tony Waltham Midlands Geological Society and printed by Norman Printing Ltd (Nottingham and London) on paper made from wood pulp from renewable forests, Lecture Reports 180 where replacement exceeds consumption. Gold in Britain – Bob Leake Deep geology of Britain – Alf Whittaker No part of this publication may be reproduced in The Isle of Eigg – John Hudson any printed or electronic medium without the prior Is the past the key to the future? – Chris Lavers written consent of the Society. Excursion Reports 184 Registered Charity No. 503617 Millstone Grit of South Derbyshire The Yorkshire Coast © 2002 East Midlands Geological Society Fountains Abbey and Brimham Rocks ISSN 0025 990X Nottingham Sandstone Caves Cover photograph: The eastern face of Bardon Hill Quarry, Charnwood Forest, exposing two Corrigenda 191 Triassic palaeovalleys that were cut into a hillside of Precambrian rocks and filled by red beds of the Supplement Mercia Mudstone Group [photo: John Carney, with The Geology of the Matlock Mines kind permission of Aggregate Industries UK]. by Trevor D. Ford MERCIAN NEWS MERCIAN NEWS together, it seems possible that the orientation of the Widmerpool graben faults, or of similar easterly structures in the basement, would enable them to absorb modern intraplate strains by allowing Melton Mowbray Earthquake portions of the crust to slide laterally past each other. At 4.25 pm on Sunday, 28th October, 2001, It could be this process, operating at depth and the East Midlands was affected by a sizeable involving no surface rupture, that periodically earthquake. It has been termed the ‘Melton generates earthquakes of the type we experienced Mowbray Earthquake’, although its epicentre was last year. actually located farther north, just west of Eastwell (SK770283). The UK Seismic Monitoring and Information Service, based at the British Geological Bingham Trails Heritage Association Survey offices in Edinburgh, determined its local magnitude to be 4.1 ML, a figure revised from the As part of the Society's charitable objectives of value of 3.8 that had been calculated immediately encouraging education, research and conservation after the event. According to the European in geology in the East Midlands we have Macroseismic Scale (EMS), its intensity of just over provided funding of £250 and intellectual support 5 denotes a strong earthquake… ‘felt indoors by many to the Bingham THA. Support by EMGS and people, outdoors by a few, with a strong vibration other local and regional bodies enabled the BTHA causing windows, doors and dishes to rattle, hanging to obtain lottery money administered by the objects to swing, doors to open and close and top heavy Local Heritage Initiative Fund. Phase one has seen objects to fall over’. Such effects were widely the publication of five free leaflets (including one experienced in an area between Mansfield, on geology), a display in the Old Court House and Northampton and Kings Lynn and some minor Bingham Library of a 1:10,000 geological map structural damage was also reported, involving fallen and other exhibits, and creation of a website chimneys and cracked walls. (www.binghamheritage.org.uk). The geological Contrary to media reports, this was not the leaflet, written by Andy Howard, is very ‘worst earthquake in 250 years’ in these parts. That impressive; it should bring a greater geological honour goes to the Derby Earthquake of 11th awareness to the residents of Bingham, and February, 1957, with an intensity of 6-7 EMS also provide useful publicity for the Society in (magnitude 5.3 ML) and an aftershock of 5 EMS an area where there is little surface geology to be (magnitude 4.2 ML). A chart of main shocks seen. experienced throughout the UK landmass would nevertheless place the Melton Earthquake currently at number 20. It was therefore an important event, although to keep it and the Derby Earthquake in Nottingham's medieval caves perspective, it should be noted that the ten largest It is unusual for a journal to include review of a earthquakes in the world since 1900 had magnitudes paper in any other journal, but it is appropriate of 8.5-9.5. in this case because of the Society's interest What caused the earthquake is a difficult and involvement with Nottingham's sandstone question to answer. Seismologists at BGS caves. The paper of note is Nottingham's Edinburgh calculate that one solution may be that underground maltings and other medieval caves: the shock was generated at a depth of 11.6 km architecture and dating by Alan MacCormick, on beneath the epicentre by a dextral, oblique slip type pages 73-99 of volume 105 of the Transactions of movement (ie extensional combined with dextral of the Thoroton Society of Nottinghamshire, strike-slip motion). This motion occurred along dated 2001. This is a significant paper on all the a northwards-dipping fault, the orientation of older caves (pre-dating 1950) known under which was east-west. Such a depth would place the Nottingham. These include the 28 cave maltings earthquake focus within early Palaeozoic basement that are Nottingham's speciality, unmatched rocks lying below a major rift structure known as elsewhere. It also covers the 27 other dated medieval the Widmerpool Gulf. The latter is a deep, caves, with illustrations and discussion on the sediment-filled graben of Carboniferous age that is carved pillars and ornamental detail that distinguish concealed by Triassic and Jurassic beds in this part them from the larger numbers of later and more of the Midlands. We know that the Widmerpool functional caves. Appendices include listings of all graben was controlled by very large faults, of the cave sites, and also a valuable series of broadly east-west orientation, extending deep into contemporary records of the older caves. Alan's the basement. We also know that the modern very welcome paper may not be an easy read tectonic regime of Britain is controlled by factors (though there are more than 40 drawings and that include pressures exerted by the south-easterly photos), but it is a fascinating and authoritative ‘drift’ of the Eurasian Plate, away from the Mid- account that adds greatly to the documentation of Atlantic Ridge. Putting these lines of evidence old Nottingham. 150 MERCIAN GEOLOGIST 2002 15 (3) MERCIAN NEWS/THE RECORD The Society logo THE RECORD Unusually for a society or organisation, the EMGS has thrived since its formation in 1964 without a logo. But the Society's imminent guidebook on the The Society has welcomed 18 new members, and geology of the East Midlands has required a logo to membership stands at nearly 400 at the end of 2001. go on the cover alongside that of our co-publishers, Special tributes were paid to three members who the Geologists' Association. Accordingly, members had recently died. Ben Bentley was unable to were asked for ideas, which were then considered by complete his term on Council due to illness; his Council. Hammers were rejected on conservation enthusiasm and energy, particularly in staffing the grounds, mammoths are used elsewhere and the Society display at numerous events and enthusing choice appeared to be which fossil was most geology to all who passed by, will be greatly missed. identified with the East Midlands. Charnia was the Edna Colthorpe and Josie Travis were founder front runner, but a draft appeared to be too members from 1964; both worked hard in the early botanical, the palaeontologists lost to the days of the Society to ensure its smooth operation sedimentologists and the Hemlock Stone was and to lay the foundations of its success today, and chosen. Various modern forms of lettering were tried both were regular attenders at Society lectures until but eventually a traditional form of letters encircling this year. the stone were chosen in a similar arrangement as used by the Geologists' Association. Field meetings Looking back in the Mercian Geologist, the secretary was surprised to find only a single The programme was disrupted by access problems reference to the Hemlock Stone - in Volume 1 part due to the outbreak of foot and mouth disease, but 1, of 1964, in a report by Dr Frank Taylor (still an four excursions were possible. active member of the Society) of an excursion he led In July 2001, Peter Gutteridge led a trip to the area to localities in the area west of Nottingham. The around the National Stone Centre in Derbyshire, Stone gets just six lines in the report. Happily, and Keith Ambrose led an evening visit to the Frank Taylor's views expressed in 1964 are still Millstone Grit of South Derbyshire. supported by geologists currently working in the In September, Andy Howard led a weekend area (see page 154 of this issue).