93 



mals lived and died, the finer volcanic ejections having, it is pre- 

 sumed, led to the formation of the volcanic sandstone. 



6. That subsequent to these contemporaneous classes, other trap 

 rocks have been forcibly intruded, amidst deposits of all ages, from 

 the oldest grauwacke up to the strata of the coal measures, pro- 

 ducing great derangement, fracture, and alteration in the beds which 

 they penetrate, exhibiting, at the points of contact, siliceous schists, 

 porcellanite, many crystallized substances, veins, quartz rock, &c. 



7. Special attention is invited to that change by which sand- 

 stone has been converted into quartz rock, because it appears to 

 explain how the so-called^rmary quartz rock may have been formed, 



8. It is inferred that all the metalliferous veins in the country 

 described are due to the presence of the contiguous trap rocks, and 

 that therefore this inquiry has amply corroborated the theoretical 

 speculations of M. Necker*. 



June 4. — A paper was first read, entitled, " Observations on 

 the Strata penetrated in sinking a Well at Diss, in Norfolk," by 

 John Taylor, Esq., Treas. G. S. 



The well alluded to in this communication affords the only details, 

 hitherto made public, of the thickness and character of the chalk 

 in that part of Norfolk in which Diss is situated. 



The well was sunk by Mr. Thomas Lombe Taylor, and the fol- 

 lowing list gives the order and thickness of the beds : 



Clay 50 feet. 



Sand 50 — 



Chalk, without flints, soft and of a marly nature 100 — 



Chalk, with flints in layers of single stones, distant ~1 „„„ 

 about a yard from each other j 



Grey chalk, with an occasional layer of white chalk, 1 „^ 

 and free from flints J 



Light bright blue chalk, approaching to clay, with 1 „^ 

 white chalk stones j 



Sand 5 — 



615 

 On penetrating the light blue chalk, the tools sunk rapidly for 

 about 5 feet, and the water rose to within 47 feet of the surface, at 

 which height it is stated to have continued. 



A paper, entitled, *' Observations on a Well dug at Lower 

 Heath, on the South Side of Hampstead," by Nathaniel Wetherell, 

 Esq., F.G.S., was next read. 



The strata penetrated in making this well are stated by Mr. 

 Wetherell to be as follows : 



London clay 285 feet. 



Rock 5 — 



Plastic clay 40 — 



330 

 * Proceedings, vol. i. p. 392. 



