Chalk Group macrofossils from the Basingstoke (Sheet 284) and Aldershot (Sheet 285) districts Geology & Landscape, Southern Britain Programme Open Report OR/07/007 BRITISH GEOLOGICAL SURVEY GEOLOGY & LANDSCAPE, SOUTHERN BRITAIN PROGRAMME OPEN REPORT OR/07/007 Chalk Group macrofossils from the Basingstoke (Sheet 284) and Aldershot (Sheet 285) districts The National Grid and other M A Woods Ordnance Survey data are used with the permission of the Controller of Her Majesty’s Stationery Office. Licence No: 100017897/2005. Keywords Chalk Group, Turonian, Coniacian, Santonian, Campanian, Lithostratigraphy, Biostratigraphy, Chronostratigraphy. Bibliographical reference WOODS, M A. 2007. Chalk Group macrofossils from the Basingstoke (Sheet 284) and Aldershot (Sheet 285) districts. British Geological Survey Open Report, OR/07/007. 25pp. Copyright in materials derived from the British Geological Survey’s work is owned by the Natural Environment Research Council (NERC) and/or the authority that commissioned the work. You may not copy or adapt this publication without first obtaining permission. Contact the BGS Intellectual Property Rights Section, British Geological Survey, Keyworth, e-mail [email protected]. You may quote extracts of a reasonable length without prior permission, provided a full acknowledgement is given of the source of the extract. Maps and diagrams in this report use topography based on Ordnance Survey mapping. © NERC 2007. All rights reserved Keyworth, Nottingham British Geological Survey 2007 BRITISH GEOLOGICAL SURVEY The full range of Survey publications is available from the BGS British Geological Survey offices Sales Desks at Nottingham, Edinburgh and London; see contact details below or shop online at www.geologyshop.com Keyworth, Nottingham NG12 5GG The London Information Office also maintains a reference 0115-936 3241 Fax 0115-936 3488 collection of BGS publications including maps for consultation. e-mail: [email protected] The Survey publishes an annual catalogue of its maps and other www.bgs.ac.uk publications; this catalogue is available from any of the BGS Sales Shop online at: www.geologyshop.com Desks. 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The Chalk succession near Tile Barn Farm [ SU 71536 48377] ((2) of report). Figure 2. The Chalk succession near Little Hoddington [ SU 7050 4856] ((3) of report). Figure 3. The Chalk succession near Roke Farm [ SU 76190 49389] ((5) of report). Figure 4. The Chalk succession at Wassels Copse [ SU 75152 49994] ((9) of report). Figure 5. The Chalk succession near Little Rye Farm [SU 77366 49890] ((11) of report) Figure 6. The Chalk succession near Up Nately [ SU 70829 51246] ((12) of report) Figure 7. The Chalk succession near Home Farm, Basingstoke [SU 65528 50489] ((16) of report). Figure 8. The Chalk succession at Odiham [ SU 73731 50622] ((18) of report). Figure 9. Key features of the Chalk succession at Odiham [SU 73731 50622] ((18) of report). See Fig. 8 for indication of scale. TABLES Table 1. The stratigraphy referred to in this report. ii OR/07/007; Released 0.1 Last modified: 2007/08/07 11:46 Summary This report provides brief stratigraphical conclusions for Chalk Group macrofossils collected from 68 sites on sheets 284 (Basingstoke) and 285 (Aldershot) during fieldwork in May 2007. iii OR/07/007; Released 0.1 Last modified: 2007/08/07 11:46 1 Stratigraphy Material collected from the Chalk Group during fieldwork in May 2007 ranges from the Turonian (T. lata Zone) to Campanian (O. pilula Zone). The stratigraphy referred to in this report is shown in Table 1. Stratigraphical conclusions for individual localities are detailed below. (1) Old chalk pit c. 525 m south of Manor Farm, Well, Hants. 1:50 000 284 (Basingstoke) NGR: SU 7618 4591 Specimen nos: WMD 12718-12742 The fauna includes the brachiopod Gibbithyris ellipsoidalis and the inoceramid bivalve Cladoceramus undulatoplicatus. Conclusion: White Chalk Subgroup, middle Seaford Chalk Formation; basal Santonian, upper M. coranguinum Zone. (2) Chalk pit c. 730 m NE of Tile Barn Farm, near South Warnborough, Hants. 1:50 000 284 (Basingstoke) NGR: SU 71536 48377 Specimen nos: WMD 12743-12756 The pit exposes 9.5 m of Chalk Group strata (Fig.1). Uintacrinus socialis and Bourgueticrinus occur in the uppermost 1.25 m of the succession. The underlying 8 m of chalk contains orange- stained, sponge-rich chalk, with horizons of Platyceramus and a flint horizon associated with several specimens of the echinoid Conulus, including C. albogalerus and possibly C. subrotundus. Conclusion: White Chalk Subgroup, upper Seaford Chalk Formation and basal Newhaven Chalk Formation; Santonian, upper M. coranguinum Zone and basal U. socialis Zone. (3) Old chalk pit near Little Hoddington, 770 m ENE of church at Upton Grey, Hants. 1:50 000 284 (Basingstoke) NGR: SU 7050 4856 Specimen nos: WMD 12757-12761 The pit exposes 4.25 m of Chalk Group strata (Fig. 2). Thick-shelled Platyceramus occurs near the bottom of the succession, and thin-shelled Platyceramus and Conulus occur around the middle of the succession. There are locally developed horizons of iron-stained, sponge-rich chalk. Conclusion: White Chalk Subgroup, upper Seaford Chalk Formation; Santonian, upper M. coranguinum Zone. 1 OR/07/007; Released 0.1 Last modified: 2007/08/07 11:46 (4) Old chalk pit c. 230 m SE of Swanthorpe House, near Well, Hants. 1:50 000 284 (Basingstoke) NGR: SU 7866 4656 Specimen nos: WMD 12762-12784 The fauna comprises very common and fragmentary echinoids in sponge-rich chalk, including Conulus, Micraster and a cidarid (spine). No evidence of Uintacrinus or Marsupites was found, favouring assignment of the fauna to the upper M. coranguinum Zone, and possibly a level close to the top of that zone where echinoids are sometimes very common. Conclusion: White Chalk Subgroup, upper Seaford Chalk Formation; Santonian, upper M. coranguinum Zone. (5) Old chalk pit c. 230 m N of Roke Farm, north of Well, Hants. 1:50 000 284 (Basingstoke) NGR: SU 76190 49389 Specimen nos: WMD 12785; ARF 1699 to 1700 The pit exposes c. 3.75 m of chalk with rounded flint nodules and a possible thin marl horizon 2.7 m below the top of the section (Fig. 3). The specimens include strongly ornamented calyx plates of Marsupites testudinarius, suggesting a level at or above the middle of the zone. The brachiopod Cretirhynchia exsculpta also occurs. Conclusion: White Chalk Subgroup, lower Newhaven Chalk Formation; Santonian, M. testudinarius Zone. (6) Excavations for new barn, c. 770 m SSW of cross roads in South Warnborough, Hants. 1:50 000 284 (Basingstoke) NGR: SU 71877 46667 Specimen nos: WMD 12793-12820 The fauna includes the following: Bivalvia: Neithea sexcostata oyster? Plagiostoma hoperi Platyceramus (shell fragments) Echinoidea: Conulus? (test fragment) Hirudocidaris hirudo (spine) The above fauna is associated with locally sponge-bearing chalk. No evidence of Uintacrinus or Marsupites was found, or of the oyster-rich fauna that usually accompanies these crinoids. Conclusion: White Chalk Subgroup, ? upper Seaford Chalk Formation; ? Santonian, ? upper M. coranguinum Zone.