,,' Professor J. W. Gregory — The Danbury Gravels. 537 



yielded the following section : Soil 1| feet, drift 41| feet, London 

 Clay 252 feet, Woolwich and Reading Beds 34^ feet, London Clay 

 repeated 53i feet, Woolwich and Heading Beds 39 feet, Thanet Sand 

 56 feet, Chalk 693 feet; total, 1,180 feet. 



Dalton (1882, p. 16) attributed this succession to a reversed fault. 

 Mr. T. Y. Holmes definitely (1891, pp. 199-200) and Mr. Whitaker 

 doubtfully (1886, pp. 168-9) accepted this view. S. V. Wood (1881, 

 p. 504; 1886, p. 79) referred the disturbance to an S-shaped fold. 

 The difference between a fold or a fault is comparatively immaterial, 

 and this bore strongly supports Wood's conclusion that a powerful 

 post-Eocene dislocation must cross Mid-Essex. This movement, 

 according to Wood & Dalton, was earlier than the high-level gravels 

 at Wickham Bishop; but according to Dr. Salter the movement was 

 later than the gravels, for it uplifted them. The probabilities are 

 in favour of Dr. Salter's view. The age was certainly pre-Glacial 

 and was probably Pliocene. This age is indicated by the following 

 considerations : — 



1. The direction of the dislocation is north-east to south-west, and 

 not east to west. 



2. The Colchester earthquake shows that the movements along 

 this line have not yet ceased. 



3. The Mid-Essex range, which extends from Tiptree through 

 Wickham Bishop, Danbury, and Billericay, was caused by this 

 uplift. The lower Chelmer was already in existence before this 

 uplift, which, being later than the Chelmer, must be much later than 

 the Danbury gravels, since they were deposited before the, erosion of 

 the Chelmer and other Mid-Essex river valleys. 



EEFEBENCES. 



Dalton, W. H. 1882. "The Blackwater Valley" : Trans. Epping Forest 



and Essex Nat. Field Club, vol. ii, pp. 15-18, pi. i. 

 Fisher, 0. 1868. " The Boulder-clay at Witham and the Thames Valley " : 



Geol. Mag., Vol. V, pp. 98-100. 

 French, J. 1891. " On the Occurrence of Westleton Beds in North-West 



Essex " : Essex Nat., vol. v, pp. 210-18. 

 Holmes, T. V. 1891. " The Geology and Scenery of the Club's Voyage 



from Maldon to Chelmsford, August 8, 1891 " : Essex Nat., vol. v, 



pp. 197-202. 



1904. ' ' Visit to the Light Bailway between Kelvedon and Tollesbury ' ' : 



Essex Nat., vol. xiii, pp. 249-50. 



Hughes, T. McK. 1868. "On the Two Plains of Hertfordshire and their 

 Gravels" : Quart. Journ. Geol. Soc, vol. xxiv, pp. 283-7. 



Meldola, B. and White, W. 1885. "Beport on the East Anglian Earth- 

 quake of April 22, 1884": Essex Field Club, Special Memoirs, No. 1, 

 x, 224 pp., pi. iv. 



Prestwich, J. 1890. " On the Belation of the Westleton Beds . . . with 

 some observations on the period of the final elevation ... of the Weald 

 and of the Thames Valley, etc. " : Quart. Journ. Geol. Soc, vol. xlvi, 

 pp. 84-181, pis. vii, viii. 



Beid, Clement. 1882. The Geology of the Country around Cromer (Mem. 

 Geol. Surv. England and Wales, Sh. 68 E.), x, 137 pp., 1 pi. 



1896. "The Eocene Beds of Dorset": Quart. Journ. Geol. Soc, 



vol. lii, pp. 490-6. 



Salter, A. E. 1905. " On the Superficial Deposits of Central and Parts of 

 Southern England " : Proc Geol. Assoc, vol. xix, pt. i, pp. 1-56. 



