Notes on the high-level (?marine), late Anglian Woolpit Beds, Suffolk

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NOTES ON THE HIGH-LEVEL, (? MARINE), LATE-ANGLIAN WOOLPIT BEDS, SUFFOLK

C. R.

BRISTOW

and Miss D . M .

GREGORY

'Brickearth' at Woolpit has been worked since at least the 16th Century (Whitaker, Bennett and Blake, 1881; Northeast, 1972) and was the source for the locally-famous bricks known as Woolpit or Suffolk Whites. Düring 1978 this area was re-surveyed by one of us (CRB) at the six-inch-to-the-mile scale (1:10 560 Sheet T L 96SE). This survey showed that the 'brickearth' overlies chalky Boulder Clay, and is locally overlain by Glacial Sand and Gravel and/or chalky Boulder Clay. The lower Boulder Clay is part of the extensive sheet of Anglian age which forms the plateau area of much of East Anglia. At Sicklesmere, some 11 km west of Woolpit, this Boulder Clay is overlain by Hoxnian deposits (Turner, 1973). In 1978 two I G S continuous flight auger holes' (Woolpit 1 & 2) were drilled into the 'brickearth'. Samples from these boreholes yielded a sparse marine Pleistocene foraminiferal fauna. This unanticipated result led to a third borehole (Woolpit 3) being drilled by taking continuous U4s ; , in order to obtain better, uncontaminated samples. In view of the distinct lithology and fauna it is here proposed to name the 'brickearth' at Woolpit as the Woolpit Beds. The Woolpit 3 borehole not only penetrated the füll thickness of the Woolpit Beds, but also continued through the Crag. The foraminifera recovered from the Crag are also listed in the faunal chart (Table 1) to enable comparison to be made between the faunas from the Woolpit Beds and the Crag, and in particular, to see whether the former could have been derived from the latter.

Stratigraphy The 'brickearth' occupies a depression in the Boulder Clay surface of approximately 1 km diameter. The deposits are at their highest around the margin where they attain a maximum height of 60 m O D . Numerous pits have been opened in the 'brickearth'; those at the margin appear to have stripped off the brickearth completely, leaving hollows now floored and flanked by chalky Boulder Clay. The largest pit [TL 982 622], and the last one 1 C o n t i n u o u s flight a u g e r — t h i s is in reality a giant screw which can be used in two d i f f e r e n t ways to obtain samples: a. by driiling into the g r o u n d without withdrawing the bit, in which case the s a m p l e travels up the a u g e r flight to the surface. This is a very quick driiling m e t h o d , but the resultant d e p t h s of the s a m p l e s a r e not k n o w n with precision. b. t h e a u g e r is drilled into the g r o u n d to fill the flights with sample and t h e n w i t h d r a w n a n d the s a m p l e r e m o v e d ; the process is t h e n r e p e a t e d . This m e t h o d gives m u c h b e t t e r control of sample d e p t h , but the driiling process is much slower as t h e r e is m u c h coupling and uncoupling of driiling stems. 2 U 4 — t h i s is the Standard t e r m for an u n d i s t u r b e d s a m p l e of 4 inches diam. S a m p l e s are o b t a i n e d by this m e t h o d by banging the U 4 tube into the Sediment until filled; it is w i t h d r a w n and the s a m p l e e x t r u d e d f r o m the U 4 t u b e .

Trans. Suffolk Nat. Soc. 18 part 4.


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