330 Reports and Proceedings — 



papers which are local and original. We regret to learn that on 

 account of this rule, the Whitehaven Scientific Association has 

 severed its connection with the Cumberland Association. Surely 

 unity is strength, and surely there are members of the Whitehaven 

 Association who could aid in the progress of science without 

 departing from the salutary rules framed for the benefit of the mauy. 

 The multiplication of local " Transactions " is a serious evil. 



BEPOBTS J^JSTJD ZPIR-OCIEIEIDIISra-S. 



Geological Society of London. 



I.— May 26, 1886.— Prof. J. W. Judd, F.B.S., President, in the 

 Chair. — The following communications were read : 



1. " Further Proofs of the Pre-Cambrian Age of certain Granitoid, 

 Felsitic, and other Bocks in North-western Pembrokeshire." By 

 Henry Hicks, M.D., F.B.S., F.G.S. 



In this paper the author gave the results obtained by him during 

 a recent visit to N. W. Pembrokeshire. He stated that he had 

 further examined some of the sections referred to in his previous 

 papers, as well as others not therein mentioned, and that he had 

 obtained many additional facts confirmatory of the views expressed 

 by him in those papers. The Lower Cambrian conglomerates and 

 grits, he said, contained pebbles of nearly all the rocks in that area 

 which he had claimed as of pre-Cambrian age ; and the fragments 

 of the granitoid rocks, the felsitic rocks, the kalleflintas, and of the 

 various rocks of the Pebidian series which he had found, showed 

 unmistakably that those rocks had assumed, in all important particu- 

 lars, their peculiar conditions before the fragments were broken off. 



Moreover, he stated that there was abundant evidence to show 

 that the very newest of the pre-Cambrian rocks of the area bad been 

 greatly crushed, cleaved, and porcellanized, before any of the Cam- 

 brian sediments were deposited ; hence he maintained that there 

 was in the area a most marked unconformity at the base of the 

 Cambrian. At Chanter's Seat, near St. David's, he found that the 

 Lower Cambrian grits and conglomerates were, in parts, almost 

 wholly made up of fragments of characteristic varieties of the 

 Granitoid rocks which form the Dimetian ridge near by. 



The so-called granite of Brawdy, Hayscastle, and Brimaston, he 

 said, there was good evidence to show, was probably of the age of 

 the Granitoid rocks of St. David's. The mass of so-called granite 

 near Newgale, he stated, was composed of rhyolites and breccias, 

 undoubtedly of pre-Cambrian age. 



The Roch Castle and Trefgarn rocks, he stated, could not possibly 

 be intrusive in Cambrian and Silurian strata, but belonged to a 

 series of pre-Cambrian rocks. He referred to the important evidence 

 bearing on the age of these rocks given in a paper communicated to 

 the Society, since his last paper was read, by Messrs. Marr and 

 Boberts. These authors showed that in a quarry near Trefgarn 



