GEOLOGY 



The Upper Chalk, consisting of chalk with nodular and tabular 

 flints, underlies the greater part of Suffolk, from Haverhill through Bury 

 St. Edmunds to Brandon, and in the country to the east, where however 

 it is so much obscured by Glacial drift and Tertiary strata that it appears 

 seldom at the surface and few fossils have been recorded. 



Chalk with Micraster occurs at Bury St. Edmunds and onwards, 

 probably to Ixworth, Fakenham and Euston Park. At Great Horringer 

 it has been extensively excavated in subterranean workings or galleries. 



The Marsupite zone probably extends through the country from 

 near Wickhambrook to Elmswell, Botesdale and Redgrave. 



Near Needham Market the Chalk yields Actimcamax quadratus, 

 Inoceramus mytiloides and Ostrea acutirostris. There are Chalk pits at 

 Coddenham, while to the north-east the Chalk appears in the Deben 

 Valley below Debenham and at Earl Soham. 



Chalk above the zone of Actimcamax quadratus might have been 

 expected along the borders of the Eocene covering from Sudbury, east- 

 wards to Claydon and Bramford near Ipswich ; but at Sudbury no indi- 

 cations of higher beds have been proved, the few fossils found there 

 including Lima hoperi and teeth of the sharks Lamna and Oxyrhina. It 

 is to be borne in mind that the thickness of Chalk proved at Combs 

 near Stowmarket is but little less than that below Stutton, where the full 

 local thickness occurs. Along the eastern borders of the county it may 

 be that higher beds occur, but information derived solely from borings is 

 necessarily meagre. 



The Chalk is the great storehouse for water, and wells and borings 

 have been carried into it in all parts of the county, excepting into its 

 lowest division of grey marl, which is impervious. Although so much 

 of the Chalk is deeply buried beneath newer strata, which consist largely 

 of impervious clays and effectually keep out the direct rainfall, yet an 

 abundant supply of good water has been obtained at Ipswich, Wood- 

 bridge and other places far from the main outcrop. Under such con- 

 ditions a supply is not always freely obtained, and it may be necessary to 

 penetrate the formation to depths ranging up to 250 feet before a fissure is 

 met with ; while along the sea borders, as at Southwold, Leiston, Orford 

 and Landguard Fort, brackish or saline waters have been encountered. 

 In west Suffolk, where the Drift coverings are neither so thick nor 

 so impervious as in central Suffolk, water is more readily obtained. Mr. 

 Whitaker has called attention to an intermittent stream or ' nailbourne ' 

 at Coddenham. After much dry weather, when the plane of saturation 

 in the Chalk is low, the brook which flows over Boulder Clay in its 

 higher course sinks into the permeable Chalk, but after long-continued 

 rain there is a continuous flow of water.' 



The Chalk is burnt for lime at Sudbury, Bramford, near Bury St. 

 Edmunds and other places; and it has been used with an admixture 

 of river-mud for cement making at Waldringfield and Burgh Castle. In 



• 'Geology of the Neighbourhood of Stowmarket,' Geol. Survey (1881), p. 18, 



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