﻿A. J. Juices Browne — On the Upper Greenmnd, etc. 357 



to class it with the Upper Greensand, but remarks that — •' In the 

 Memoir on Sheet 12 this bed was described as Chloritic Marl, and 

 was classed with the Chalk. This was done at the suggestion of 

 Prof. Edw. Forbes, 'because in Dorset and in the Isle of Wiglit 

 ibcaphtes, etc., were supposed first to appear in a bed which is con- 

 sidered to be the same as this." To this difference of opinion I shall 

 have occasion to refer again presently. 



There is another district in which a bed has often been described 

 as occupying a similar position ; this is the outlying area of Cre- 

 taceous beds in the counties of Devon and Dorset. Mr. Davidson, in 

 his Monograph of the Cretaceous Brachiopods, gives the following suc- 

 cession as seen in the neighbourhood of Chard and Chardstock : ' — 

 I. Lower Chalk without flints.. 



II. Chalk Marl, with fine siliceous and chloritic grains, and Am. Manfelli, 

 Discoidea cylmdrica, Hoi. stcbglobosus, etc. 



III. The Scaphites Bed, 3 to 9 inches thick, a compact accumulation of fossils and 



siliceous grains — Scaphites, Nautilus triangularis, ]SF. Icevigatus,- Am. 

 varians, etc. . 



IV. V. VI. The Upper Greensand in three beds. 



This " Scaphites bed " is evidently the analogue of the Chloritic 

 Marl, and the bed below is described as distinctly separated from it. 

 In 1870 Mr. Whitaker divided the Upper Greensand of Beer 

 Head from glauconitic beds above, which he doubtfully referred to 

 the Chalk Marl, and which he showed in an accompanying section 

 as overlapping the lower strata." Mr. De Eance afterwards made a 

 further subdivision of the beds in West Dorset, establishing a suc- 

 cession of five different zones. ^ 



I. Zone of Scaphites cequalis.- 



ill. Zone of Pecten asper,. 20 feet. 

 III. Zone of Exogyra conicaylb feet. 

 IV. Fox-mould, 60 feet. 

 V. Cowstones (? 40 feet); 



The first of these he considers to be the Chloritic Marl, and the 

 last he refers to the Upper Gault, leaving the three middle zones in 

 the Upper Greensand. 



In the same year Mr. C. J. A. Meyer published a paper on the 

 relative horizons of the Warminster and Blackdown deposits,'' in 

 which he divides the beds of the Beer Head district into a number 

 of zones, and groups these into four larger divisions, viz. the Black- 

 down beds, the Upper Greensand, the Warminster beds and the 

 Chalk Marl, thus limiting the UjDper Greensand still more by sepa- 

 rating from it the Warminster beds or Pecten asper zone, reducing it 

 indeed to little more than the equivalent of the Ex. conica zone of 

 Mr. De Eance. Speaking of the Warminster beds he says, "They 

 are seen to cap the Upper Greensand, and are therefore in reality 

 Chloritic Marl," a conclusion which he considers to be borne out by 

 the evidence of the fossils. 



As however the fauna of the Warminster beds has subsequently 

 been found in the Upper Greensand of the Isle of Wight below the 



1 Pal. Soc. Mem. 1852, p. 114. 



2 Quart. Journ. Geol. S^c, vol.. xxvii. p. 98. 



3 Geol. Mag. Dec. II. Vol. I. p. 196. 



* Quart. Journ. Geol. Soc. vol. xxx. p. 369. 



