North-west Region of Charnwood Forest. 143 



mingled with those of the deep-seated ones (Teifengesteine). These 

 have, aside from the porphyritic structure, a schlieren structure re- 

 vealed by a peculiar fluted weathering (illustrated by a photograph) 

 and the presence of pseudo-crystals in the form of leucite. 



Stratigraphically the Tingua foyaites lie in sheet-like masses like 

 lava-flows, extending from the higher to the lower portions of the 

 mountain, the underlying gneiss being revealed at nearly all levels, 

 wherever the mass has been scored by streams. The general frag- 

 mentary character of the rock seems to be due to the undermining 

 of these sheets. 



Specimens and photographs illustrating the peculiar pseudo- 

 crystals in the form of leucite that occur in both the foyaites and 

 phonolites of Tingua (although no leucite has been detected in the 

 rock) were exhibited and discussed. 



2. " The Variolitic Diabase of the Fichtelgebirge." By J. Walter 

 Gregory, F.G.S., of the British Museum (Natural History). 



The author has examined the variolitic diabases in the neigh- 

 bourhood of Berneck, and adduces evidence of their having been 

 intruded into the Devonian rocks before the latter were affected by 

 the great earth-movements which have folded the palaeozoic rocks of 

 the district. He finds that the variolitic structure occurs in two 

 different arrangements : (a) on the surfaces of spheroidal masses of 

 compact diabase, which are comparable with those of Mt. Genevre : 

 (b) as a true contact-product on the selvage of the diabase, the latter 

 being comparatively rare, and the varioles less perfectly developed. 



He gives proofs that the varioles are true spherulites, and not 

 fragments of Devonian rocks, as supposed by von G umbel. He 

 argues that though they are the product of rapid cooling, too sudden 

 a solidification of the diabase may prevent their formation, and that 

 for a similar reason the amygdaloidal is less variolitic than the com- 

 pact diabase, the loss of the water that occupied the vesicles having 

 diminished the fluidity of the rock. Finally, he maintains that the 

 " pseudo-crystallites " are rifts and fissures due to contraction, and 

 that the remarkable optical properties described by Michel-Levy are 

 due to the filling-up of cracks by felspathic matter deposited in optical 

 continuity with the crystalline fibres on each side. 



January 7, 1891.— Dr. A. Geikie, F.R.S., President, in the Chair. 



The following communications were read : — 



1. " On the North-west Region of Charnwood Forest, with other 

 Notes." By the Rev. E. Hill, M.A., F.G.S., and Prof. T. G. Bonney, 

 D.Sc, LL.D., F.R.S., V.P.G.S. 



The paper contains the results of a re-examination of the North- 

 west Region, when the authors had the advantage of using the six- 

 inch Ordnance-map, published since the completion of their former 

 work. In this they had expressed the opinion that the rock of 

 Peldar Tor and that of High Sharpley were somewhat altered pyro- 

 clastics, being much influenced by the non-igneous origin asserted 



