92 Correspondence — Mr. E. B. Taivney. 



The external coating of ferric oxide must therefore have been 

 deposited subsequently to the rounding of the grains ; it could not 

 have been derived from an external decomposition of the grains 

 themselves ; and it becomes difficult to imagine in what manner the 

 superficial red coating can have been produced. The author compared 

 these grains with those of the millet-seed sandstones of Triaasic age, 

 with which they closely agree in character, but remarked that the 

 conditions of their occurrence were apparently quite different, 



4. " Analyses of five rocks from the Charnwood Forest District." 

 By E. E. Berry, Esq. Communicated, with Notes, by Prof. T. G. 

 Bonney, F.K.S., Sec. G.S. 



These analyses are of hornblendic granite from Mount Sorrel, 

 "syenite" from Markfield, Grarendon, and Croft Hill, and "porphy- 

 roid " from Sharpley. In the main they confirm the views expressed 

 b}'' Messrs. Hill and Bonney in their communications on the subject, 

 arrived at from microscopic examination, as to the nature and 

 affinities of these rocks. 



coiaiaiESiE'OZsriinEi^oiB. 



THE FOLKESTONE BEDS. 



SiK, — In the discussion at the meeting of the Geological Society 

 on Dec. 7, 1881, it was mentioned by Prof. Judd that, according 

 to Dr. Barrois, the Folkestone beds belonged rather to the Gault 

 than to the Neocomian. 



It is well known that the top bed of the glauconitic grits at Copt 

 Point contain, as mentioned by Mr. Topley (Q. J.G.S. vol. xxiv. p. 47) 

 Amm. mammillaris, A. Beiidanti, Inoceramus Salamoni, to which may 

 be added J. concentricus, etc., and for this reason, in 1860, M. Gaudry 

 proposed to separate this horizon at Folkestone and Wissant from 

 the Neocomian, and place it in the Gault. Probably most observers 

 will agree to draw the line of separation by the former Ammonite. 



But below the mammillaris-bed at Folkestone, we begin to find 

 the large Exogyra sinuata ; in my notes I find it stated that it is 

 not uncommon, whilst Janira quinquecostata was also seen in the 

 grits at Copt Point. Moreover these observations are not un- 

 supported. In the Woodwardian Museum are a series of fossils 

 from these grits and the sands between them from near Copt Point, 

 collected by Messrs. H. and W. Keeping, which make the Neocomian 

 age of the Folkstone beds a matter of no uncertainty. These are from 

 the grits, Ex. sinuata, Pecten orbicularis, Janira quinquecostata, 

 Avicula pectinota, Gucullcea fibrosa ; from the sands, Lucina Vectensis, 

 Trigonia alcpformis, Pectunculus cf. umbonatns. Sow., Cucullcea, Astarte 

 numismalis, D'Orb., Tellina, Bhynchonella cf. elegans, Sow. 



Dr. Barrois has already noted the presence of Ost. aquila (sinuata) 

 in the Folkestone sands (Ann. Soc. GeoL Nord. voh ii. p. 46), but I 

 was not aware that it occurred in the same bed with A. mammillaris 

 as he implies, though doubtless it does so in the Argonne, etc. (ibid. 

 pp. 23, 34, 58). Probably English geologists will still continue 

 indisposed to classify the Folkestone, the Sandgate, and the Hythe 

 beds as proposed (ibid. p. 56) with the Gault. 



