GEOLOGY 



Chesterford, Hadstock, and Sturmer near Haverhill, includes at its base 

 the Melbourn Rock, named from the Cambridgeshire village of Mel- 

 bourn. This is a hard rocky chalk with marly and nodular layers, about 

 ten feet in thickness. The mass of the Middle Chalk above is well 

 bedded in layers that appear to be lenticular or wedge-shaped, and it has 

 but few flints. Among the fossils are Rhynchonella cuvieri, Terebratulina, 

 and Ho/aster subglobosus. The last-named fossil is found also in a band 

 of hard cream-coloured limestone with green coated nodules and grains 

 of glauconite, known as the Chalk Rock, which separates the Middle 

 from the Upper Chalk. The Chalk Rock has been observed in several 

 places in the northern portions of the county. 



Between Heydon and Chishall the Chalk is locally disturbed, and 

 instead of the normal southerly or south-easterly dip at a gentle angle, 

 the strata are inclined at an angle of 25 N.N.W., and the flints are 

 fractured. This high dip increases to the south-west in Hertfordshire. 

 Whether the disturbance is due to faulting or to the surface derange- 

 ments produced by glacial agents has not been satisfactorily determined. 

 That glacial action has been potent is manifest from the deeply excavated 

 trough near Newport, to which reference will be made. 



The Upper Chalk, which lies about 43 feet below the surface 

 near the Thames at Beckton, appears above ground at Grays and Purfleet 

 in south Essex ; and in the north it may be seen at Farnham and 

 Clavering in the Stort valley, at Quendon, Newport, Audley End and 

 Saffron Walden in the Cam valley, and eastwards at Great Yeldham and 

 Middleton, near Sudbury. It consists of soft chalk with layers of flints, 

 and yields remains of the saurian Leiodon (allied to Mosasaurus), of fishes 

 such as Ptycbodus polygyrus, molluscs including Inoceramus and Lima, 

 brachiopods such as Terebratula carnea, the echinoderms Cu/aris and 

 Goniaster, as well as crinoids and corals. 



At Purfleet, Grays and West Thurrock the Chalk has been largely 

 used in the manufacture of whiting, lime and cement. 



At Hangman's Wood a remarkable series of excavations known as 

 Deneholes occur. These are shafts carried through about 50 or 60 feet 

 of gravel and Thanet Sand, and 20 feet or more into the Chalk, but 

 as their interest is mainly archaeological they will be described else- 

 where. 



There is no doubt that the Chalk has been used 'from time im- 

 memorial ' for chalking the land, and more extensively in old days. 

 Arthur Young in 1768, after remarking on the badness of the road 

 between Billericay and Tilbury, observed that ' to add to all the infamous 

 circumstances, which concur to plague a traveller, I must not forget 

 the eternally meeting with chalk-waggons.' He mentioned also that 

 Chalk was brought from Kent by sea to Maldon. 1 



At Stifford the Chalk has not only been worked in open pits, but 

 also by means of shafts or ' chalk-wells,' evidence of which was brought 



1 A Six Wteki Tour through the Southern Counties, p. 72 ; see also hi General P'ten eftbe Agritulture 

 of Essex, vol. ii. (1807) p. 206. 



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