A HISTORY OF SUFFOLK 



lying strata certain slaty rocks were entered. In character they re- 

 sembled beds reached beneath the Gault at Harwich, now believed to 

 belong to the Silurian or an older formation. The enterprise at Stutton, 

 as remarked by Mr. Whitaker, was the first attempt made by the 

 Eastern Counties Coal-boring Association.^ 



An earlier boring at Culford Park to the north-west of Bury 

 St. Edmunds proved dark slaty rock and hornstone beneath the Lower 

 Greensand and overlying rocks, at depths of from 637I to 657^ feet.^ 



This is all we at present know of the Paleozoic floor in Suffolk. 



JURASSIC 



KIMERIDGE CLAY 



This formation perhaps directly underlies the alluvium in the 

 northern portion of Mildenhall Fen in a very small area in Suffolk, but 

 it may extend beneath the Lower Greensand and Gault and overlying 

 strata towards Newmarket and Mildenhall. Its thickness is not likely 

 to exceed 100 feet, and where exposed beyond the borders of Suffolk 

 it consists of dark shales and clays with nodules and bands of limestone. 

 The occurrence of limestones in the Kimeridge Clay, as at Littleport 

 north of Ely, is interesting, as in other Jurassic formations the develop- 

 ment of limestones at the expense of clays occurs in proximity to old 

 land-tracts.' The Kimeridge Clay, if not faulted against the older 

 rocks, must abut against them in the area to the west of Culford. 



CRETACEOUS 



LOWER GREENSAND 



In the boring at Culford, previously mentioned, the Pala20zoic rock 

 was immediately overlain by greyish-brown ferruginous sandstone and 

 sandy limestone with foraminifera and fragments of echinoderms, mol- 

 lusca and brachiopods, as well as lignite. These strata occurred beneath 

 the Gault, from 605 to 637I feet in depth, and they have been referred, 

 with doubt, by Mr. Whitaker and Mr. Jukes-Browne to the Lower 

 Greensand, though they mention the possibility of their being Jurassic* 



GAULT 



Although the Gault nowhere appears at the surface in Suffolk, it 

 cannot be far below ground over much of Mildenhall Fen, and it prob- 

 ably everywhere underlies the Chalk. It occurs at a depth of 532 feet 

 below Culford, and consists of a mass of grey marl 73 feet thick, in 



1 See address by W. Whitaker to Geo]. Section, Rep. Brit. Asm. for 1895, p. 667, also pp. 436, 

 693 ; and Geol. Mag. (1895), p. 466. 



* Whitaker and Jukes-Browne, ^lart. Journ. Geol. Soc. 1. 492. 



* H. B. Woodward, 'Jurassic Rocks of Britain,' vol. v. (1895), Geol. Sutfey, p. 172. 



* ^art. Joun:. Geol. Soc. 1. 493. 



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