114 W. S. M. — Notes ami Queries on English Strata. 



B. From the time of Smith's maps ^ of England, and of Web- 

 ster's letters to Englefield (1816), the deposits between the 

 Portland beds and the Chalk were regarded as naturally 

 divided thus: — 1. Greensand; 2. An argillaceous deposit 

 (Tetsworth Clay of Greenough); 3, Ironsand. 



Conybeare and Phillips (1822) followed this division, giving 

 No. 2 the name "Weald Clay" which had been suggested 

 by P. J. Martin. 



In mapping they grouped the "Chalk Marie" with the 

 Greensand, Their small map, based on a reduction of the 

 Greenough map, piablished three years earlier, shows that 

 while in some districts advance had been made in recogniz- 

 ing the distinctiveness of formations which Smith had con- 

 founded together, yet that in other districts they still mistook 

 Lower Greensand for Hastings sand. Gait for Weald Clay, 

 and even Kimmeridge Clay for Weald Clay. The first who 

 pointed out the existence of Upper Greensand, Gait, and 

 Lower Greensand, as apart and quite distinct from Weald 

 Clay and Hastings-sand, was Fitton, in a paper in the An. 

 Phil., 1824, vol. viii., " On the Beds between Chalk and 

 Purbeck." [Sedgwick had, in 1822, in the An. Pliil., pointed 

 out that in the Cambridge district the Greensand above the 

 tenacious Blue Clay which rests on the " Ironsand " is not 

 the same as the beds so named elsewhere, i.e. the (Lower) 

 Greensand.] He shows this to be so in the I. of W. and 

 S. E. of England, and gives evidence in favour of the Gait, 

 his "Marl of Folkestone" and "Clay of Undercliff" being 

 identical with the Gait of Cambridge, and adds that the 

 greater part of England has not been examined with 

 sufficient care to admit of correlation. 

 C/. Fitton's position for his Firestone has remained unaltered, 

 but the name was changed to Upper Greensand. [I cannot be 

 sure who made the change in the first place. Firestone was 

 inapplicable in a large portion of England, and the change 

 was but a restoration of Smith's name (which Sedgwick 

 insisted on in 1826, An. Phil. p. 343). Query — When was 

 "Upper" added?] 

 HuKSTANTON Ked Limestone. A. (a) Seeley. (6) 1861. (c) An. 

 Mag. Nat. Hist. Ap., 1861. {d) Hunstanton Eed Limestone. 

 (e) Hunstanton being the typical locality. 



B. Sedgwick, in the An. Phil., 1822, hinted that it was 

 distinct from Chalk. Wiltshire, in 1859, Proc. Geol. Assoc, 

 suggested, amongst other hypotheses, that it was a formation 

 intermediate between the Chalk and Lower Greensand. 



C. Clearly separated from Eed Chalk in 1864. (Quart. Journ. 

 Geol. Soc, November, 1864.) 



^ I haye used the -word in the plural with an intention. Many modifications 

 ■were made in the mapping during the period of the issue of the different copies. 

 They were not called separate editions, but containing such differences they can 

 hardly be spoken of as the same map, — W. S, M, 



