Vol. 50.] BOEINGS AT CULFOED, WINKFIELD, WAEE, AND CHE8HTTOT. 507 



have found reason to place it at about 590 feet. The Upper Green- 

 sand, then, is about 40 feet thick, and cannot be more than 44 feet. 



With regard to the supposed Lower Greensand, we cannot accept 

 the idea of its existence. The material found at the base of the 

 Gault, and resting on the Wenlock Beds, is just such a basement- 

 bed as might be expected in such a position. It consists of the 

 debris of Palaeozoic rocks mixed with glauconite, and so far as its 

 mineral composition goes it might belong to any member of the 

 Cretaceous series. One of us had already suggested that this bed 

 might be the base of the Gault, though without any evidence. It is 

 satisfactory to be able to take out so very thin a representative of 

 the Lower Greensand. 



As a matter of fact, there is generally a bed of such sand at the 

 base of the Gault ; not only does it occur at Folkestone above the 

 basement nodule-bed, but also below London, in the boring at Meux's 

 Brewery, where the base of the Gault is described as follows 1 : — 



Greensand and clay 2^ feet. 



Seam of phospbatic nodules and quartzite-pebbles ^ foot. 



Again, at Richmond, the lowest bed of the Gault is very sandy, 

 full of glauconite-grains, and passes down into a pebble- bed con- 

 sisting of phosphate-nodules, fragments of Palieozoic rock, and sand, 

 from the same source. 2 



We do not know whether any phosphate-nodules occurred at 

 Ware, but the 18 inches of sand is evidently similar to that in the 

 same position at Richmond and London. 



With regard to the Wenlock Beds, these were originally described 

 by Mr. Etheridge in 1879 as ' Wenlock Shale ' ; but Mr. Hopkinson in 

 the paper before mentioned states that there were thin intercalated 

 beds of limestone. This is confirmed by the samples before us, which 

 are all either of hard mudstone or of limestone ; and also by the 

 specimens preserved in the Museum of Practical Geology. Mr. 

 Rudler informs us that the core referred to by Mr. Etheridge is over 

 3 feet long and has a circumference of 3| feet ; it consists of dark- 

 grey mudstone, slightly calcareous, and including thin bands of 

 brownish limestone ; it is marked as coming from 82b' feet. This 

 is probably the depth of the base of the core, as samples of similar 

 material were sent us from 827 feet. There are also at Jermyn Street 

 three specimens from 820 feet, one a limestone containing Stro- 

 pliomima rhomboidalis, the others of mudstone containing PhacojJS 

 caudatus and Ischadites Kcenir/i. 



In calling these beds ' Wenlock Shale ' Mr. Etheridge probably 

 used the term in a stratigraphical, not in a strictly lithological 

 sense ; but considering the frequency and purity of the limestones, 

 which are not merely calcareous concretions, it is quite as likely 

 that the beds represent the Wenlock Limestone as the Wenlock 

 Shale. It will be safer, therefore, to speak of them merely as 

 Wenlock Beds. 



1 Quart. Journ. Geol. Soc. vol. xxxiv. (1878) p. 912. 



2 Op. cit. vol. xl. (1884) p. 7^7. 



