in East Anglia in Tertiary Times. 199 



parallel in that underlying the fossiliferous Cambrian rocks at the 

 Spinney Hills, Leicestershire. 1 Whatever classification may be adopted 

 for the beds reached in the boring at Saffron Walden, in North-West 

 Essex, it is clear that a good thickness of Jurassic rocks is present 

 here, and the Palaeozoic floor occurs at a greater depth than in Suffolk 

 and the London area. Dr. Morley Davies, in discussing the contours 

 of the ancient platform under the East of England, 2 has suggested that 

 the Mesozoic Rocks below Saffron Walden probably lie in a trough in 

 the Palaeozoic floor on the north-east of, and complementary to, 

 Professor Kendall's main Charnian axis through Bletchley, etc. 

 Dr. Davies indicates also the subsequent rise of the floor under Suffolk 

 (contour map, loc. cit., pi. xxxiv). Mr. H. A. Baker, F.G.S., in 

 working at the problem of the movements which have affected the 

 London Basin, 3 arrived independently at a similar conclusion, and was, 

 the writer believes, the first actually to state the opinion that a 

 secondary Charnian axis of unrest, parallel to Professor Kendall's main 

 axis, occurred diagonally across Suffolk and the Thames estuary. 

 Mr. Baker finds evidence of instability along this axis, in the 

 Mesozoic rocks north-east of Dover, as well as in the Lower 

 Cretaceous rocks of North-West Norfolk. He considers that its 

 north-westerly prolongation coincides with the Louth- Willoughby 

 anticline, a conclusion with which the writer cannot agree. It 

 seems more probable that the irregularity of the Chalk in North- West 

 Norfolk is connected with this anticline. Three anticlines of Charnian 

 trend would thus lie in echelon. 4 



Some years ago the writer ascribed the change in strike of the Chalk 

 at several points in the East of England to a possible bending over 

 the knee of the Palaeozoic platform beneath, and the coincidence of 

 strong through-valleys and breaches in the Chalk escarpment at the 

 point where the strike varied (points which might very well be termed 

 the " points of deflexion ") was commented upon. A few examples of 

 these points of weakness, due to a kind of anticlinal arrangement of 

 the Chalk, are the Wash Gap, 5 the Little Ouse-Waveney through- 

 valley, revealed by the Chalk surface-contours, and probably post- 

 Eocene and pre-Pliocene in age, the group of convergent valleys in 

 South-Kast Suffolk, the Hitchin Gap, the Goring Gap, etc. 



Somewhat later, in his Presidential Address to the Geological 

 Society, 1913, 6 Dr. A. Strahan touched upon the same question in 

 drawing attention to the Medway Gap at the change in strike of 



1 Quart. Journ. Geol. Soc, vol. lxviii, 1912, Proceedings, p. cviii. 



2 Dr. A. Morley Davies & J. Pringle, " On two deep Borings at Calvert 

 Station (North Buckinghamshire) and on the Palaeozoic Floor north of the 

 Thames " : Q.J.G.S., vol. lxix, p. 308, 1913. 



3 In manuscript, a copy of which was kindly sent. to the writer in July, 1914. 



4 Since the above was written Mr. B. H. Bastall has informed me that there 

 is evidence in Cambridgeshire of the north-easterly movement of the Charnian 

 axis through Sandy. See also Geology in the Field, pt. i, p. 140, 1909. 



5 Professor W. G. Fearnsides, whom I have to thank for discussing several 

 points with me, mentioned that Dr. J. E. Marr has drawn attention to the 

 coincidence of the Wash Gap and the change in the strike of the Chalk, but 

 Dr. Marr tells me he has not yet discussed the matter in print. 



6 Q.J.G.S., vol. lxix, Proceedings, p. lxxv, 1913. 



