374 Geological Society : — 



It was pointed out in opposition to these views, that the observa- 

 tions of Emmons, H. D. and W. B. Rogers, Mather, Sir W. Logan, 

 James Hall, E. Hitchcock, C. H. Hitchcock, Hager, and Wing 

 prove that the Taconic schists and limestones are in conformable 

 succession and of Silurian age. The stratigraphical structure of the 

 Taconic range is, indeed, so simple that all observers who have studied 

 it have described the schists and limestones as conformable ; and 

 numerous characteristic Silurian fossils have been found in both. 

 This view had been maintained by Dr. Sterry Hunt himself till 

 1878, when he first propounded his new interpretation of the strata 

 in question ; but the latter was not based on any fresh facts or ob- 

 servations. 



The author's own observations on the subject, carried on during 

 many years, were detailed and illustrated by a map of the whole of 

 the Taconic range. In conclusion he pointed out that, even if Dr. 

 Sterry Hunt's general principle were conceded (and he was not by 

 any means himself prepared to make such a concession), it would 

 have no bearing on the point at issue ; for the supposed younger 

 strata do not dip against the Taconic schists. In opposition to the 

 view that the geological age of strata can be inferred from their 

 mineral characters, he pointed out what remarkably different rocks 

 have been produced by the metamorphism, in different degrees, of 

 the strata of the Taconic range. 



2. "On some Nodular Felsites in the Bala Group of North 

 Wales." By Prof. T. G. Bonney, M.A., E.R.S., Sec.G.S. 



These peculiar felsites are chiefly found in one or two localities 

 in the neighbourhood of Bettws-y-coed and of Conway. In the 

 former case, in the same mass are found ordinary compact felsite 

 exhibiting under the microscope fluidal structure, a peculiar rock 

 resembling a greenish schist, and various nodular felsites (with 

 cleavage) showing nodules sometimes 3 or 4 inches in diameter, 

 some being solid, others hollow or more or less filled with chal- 

 cedony, chlorite, chalybite, &c. The nodules never exhibit a radial 

 structure ; and there is no difference of importance between their 

 structure and that of the ordinary rock. The author showed that 

 the schisty rock is only an amygdaloidal felsite, in which, after 

 cleavage, a secondary (micaceous?) mineral has been deposited along 

 the cleavage-planes. As regards the nodular structure, he showed 

 that it is analogous to the spheroidal structure seen on a larger scale 

 in many igneous rocks, and on a smaller scale in perlite, and gave 

 reasons for its being frequently associated with vesicular cavities. 

 The infiltration of these cavities and consequent solidification was 

 almost certainly prior to the production of the cleavage-surfaces, 

 which are distorted by them. The Conway felsites exhibit similar 

 phenomena, except that they are practically uncleaved. 



3. " On the Cambrian (Sedgw.) and Silurian Bocks of Scandi- 

 navia." By J. E. Marr, Esq., B.A., F.G.S. 



The author has examined the following areas of Cambrian and 



