115
HOLTON GRAVEL PIT
A BOREHOLE AT WENHASTON, NEAR HALESWORTH HOWARD MOTTRAM In 1984 I logged some boreholes that were drilled in the Blyth River Gravel Pit at Wenhaston. One borehole (BH 5) went through the Paleogene (Lower Tertiary) strata which are relatively thin hereabouts and are poorly documented in drillers’ well logs. Although the original log of this, and other boreholes drilled at the site, have been supplied to the BGS on a few occasions, the information still doesn’t appear in Onshore Borehole Records in the BGS Information Hub. Since the time when I logged the borehole, the identification and naming of the various Paleogene strata found in the region has evolved; - Knox et al., 1990; Moorlock et al., 2000; Aldiss, 2012; 2014; 2015; King, 2016. It is therefore worthwhile not only of taking the opportunity of putting the log into the public domain but to also provide it in an updated form. Notes • In the table overleaf, names of Paleogene strata have been italicised for clarity. • The pebbles in the gravels of the Westleton Beds were composed of flint. No quartzose pebbles were found in the borehole. • The beds here attributed to the Upnor Formation are muddier and less sandy than is usual for this stratum. Here the beds are more akin to the lower part of the “Hales Clay” (HC1) which may be considered as a northerly equivalent of the Upnor Formation. • The top 30mm of the Chalk was very strong and resembled porcellaneous limestone. • The BGS had a borehole drilled in 1992 at TM 4178 7627. This was 850m eastsouth-east of BH 5 and the BGS borehole (“Halesworh Borehole”) encountered the tops and bases of the different Paleogene facies and the top of the Chalk at very similar levels to those in BH 5. References Aldiss, D. T. (2012). The stratigraphical framework for the Palaeogene successions of the London Basin, UK. British Geological Survey, Open Report OR/12/004. Aldiss, D. T. (2014). The stratigraphical framework for the Palaeogene successions of the London Basin, UK., version 2 with minor revisions. British Geological Survey, Open Report Open Report OR/142/008. Aldiss, D. T. (2015). Paleogene. In Lee, J.R., Woods, M.A. & Moorlock, B.S.P. (eds), British Regional Geology: East Anglia. 81-89. British Geological Survey, Keyworth. King, C. (2016). (ed. Gale, A. S. & Barry T. L.). A revised correlation of Tertiary rocks in the British Isles and adjacent areas of NW Europe. Special Report Number 27. The Geological Society of London. Knox, R. W. O’ B., Morigi, A. N., Ali, J. R., Hailwood, E. A. & Hallam, J. R. (1990). Early Paleogene stratigraphy of a cored borehole at Hales, Norfolk. Proc. Geol. Ass. 101, 145-151. Moorlock, B. S. P., Hamblin, R. J. O., Booth, S. J. & Morigi, A. N. (2000). Geology of the country around Lowestoft and Saxmundham. Memoir of the British Geological Survey, Sheets 176 and 191 (England & Wales). British Geological Survey, Keyworth. H. B. Mottram
salhow@talktalk.net Trans. Suffolk Nat. Soc. 58 (2022)