TRANSACTIONS OF THE SECTIONS. 53 



which break through the strata even as late as those containing oolitic fossils, and 

 consequently must be regarded as younger than the oolitic period, but, as far 

 as researches have yet shown, are probably not posterior to the deposition of the 

 cretaceous strata. In this case, instead of quartz veins carrying the gold from 

 the granite into the neighbouring strata, we have veins of metallic sulphides and 

 arsenides acting in the same manner, and find the gold imbedded in its metallic 

 state in the compounds of sulphur and arsenic, with iron, copper, &c. ; and from 

 some unknown cause the more superficial parts of these veins appear as a rule to 

 be much richer in gold, which by the miners is generally supposed to decrease in 

 depth. 



The minerals commonly found in these veins are not the same as in the metallic 

 veins mentioned as also occurring with the granitic rocks under the first head, and, 

 as far as observations have gone, the metals tin, tellurium, tungsten, titanium, sele- 

 nium, &c, are never found in these auriferous veins of later date. 



Nothing could be more conclusive than the totally distinct age of these two sets 

 of auriferous eruptive rocks, which the author believes to represent the only ages 

 at which gold has been introduced into the upper crust of the globe, and thinks it 



n-obable that this generalization may be carried into other parts of the globe, if it 



e not altogether universal. 



E 



On the Igneous Hocks of South Staffordshire. 

 By David Forbes, F.li.S. 



At the request of the Local Committee of this Section, I undertook to investigate 

 and report upon the igneous rocks of Staffordshire, and at first had some hopes of 

 laying before the Section, at this Meeting of the Association, a more complete re- 

 port upon the chemical and mineralogical nature of these rocks. Upon getting 

 deeper, however, into the subject, I found that all the results which I could collect 

 from the labours of previous investigators were but of little service, and contained 

 so many discrepancies that I was compelled to commence the investigations ab initio. 

 As my time could not be exclusively devoted to this inquiry, it was evident that 

 in the few months (from March) which would elapse before the Meeting of the 

 Association took place this year, it would be quite impossible to do any justice to 

 the subject, especially as the careful chemical examination of many rocks as were 

 desirable would in itself take up some months' labour. I come forward, therefore, 

 with the present communication simply to report progress, and to show that the 

 investigation has not been neglected, and I trust that at the next year's Meeting of 

 the Association I may be enabled to present a more complete and detailed commu- 

 nication. I shall therefore merely give a sketch of the system pursued in the in- 

 quiry, and shall leave the details until I have the honour of laying a second report 

 before the Section. 



After having collected all the published information on the subject that was 

 attainable, of which by far the most important is contained in Mr. Beete Jukes's 

 valuable "Memoir on the South Staffordshire Coal-Field," I found that our chemi- 

 cal knowledge was confined to some two or three analyses made at random, if I 

 may so speak. The two analyses of Eowley Rag and Whiterock-trap, made by 

 Mr. Henry, and inserted in Mr. Beete Jukes's Memoir, represent, no doubt, the 

 exact composition of the hand specimens sent to Mr. Henry, whose skill was un- 

 questionable ; yet I have quite satisfied myself that they do not represent the com- 

 position of the rock-masses in general, aud would not be such as a geologist would 

 select to represent what he considered as a fair specimen of what the rock-mass 

 really was. 



In these investigations it is absolutely essential that the chemist, geologist, and 

 mineralogist should go hand in hand in the inquiry. It was therefore resolved to 

 make a personal visit to each of the principal localities where these rocks occurred, 

 and to select carefully specimens which would fairly represent the unaltered rock- 

 mass, distant as far as possible from the external surface, which, naturally, are in- 

 variably more or less altered by the action of air, water, carbonic acid, &c, as also 

 from the intermixture and absorption of more or less of the surrounding strata 

 with which they come into contact. It is quite evident that without such precau- 



