﻿Geological Society. 501 



The book will then be a very serviceable introduction to quaternions, 

 although we should like to see a more logical and thorough hiving 

 down of the foundations of the calculus. Especially does the 

 whole question of vector and versor require careful presentation. 

 else w r ill the triple dynasty of antiquaternionic vector analyses 

 let loose their invective, their scorn, and their specious pleadings. 



LX. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 



[Continued from p. 423.] 



May 9th, 1894.— Dr. Henry Wcodward, E.R.S., President, 

 in the Caair. 



The following communications were read : — 

 HPHE following communications were read : — 

 -■- 1. ' Ca rock Fell: a Study in the Variation of Igneous llock 

 masses. — Part I. The Gabbro.' By A 1 red Harker, Esq., M.A., 

 F.C.S. 



The paper opers wibh an accourt of the general relations of the 

 intrus've rock-masses of the district, ana proceeds to deal more 

 particularly with the gabbro, which forms the earliest intrusion. 



A penological description of the Carrock Pell gabbro is followed 

 by a study of the variations observed in different parts of the mass. 

 The rock becomes progressively more basic from the centre to the 

 margin, passing from a quartz-gabbro with as much as 59 \ per cent, 

 of silica to an ultrabasic type with as little as 32 1. The latter in 

 extreme cases contains nearly 25 per cent, of iron-ores, partly 

 titauiferous. This is compared with the igneous iron-ores described 

 by Vogt in Scandinavia, &c, and the probable physical cause of the 

 remarkable variation in the gabbro is discussed. 



Other modifications of the gabbro are briefly noticed, due on the 

 one hand to metamorphism of the rock by a somewhat lf.ie: 

 intrusion of granophyre, on the other hand to the gabbro-magma 

 having enclosed considerable masses of the basic lavas of the 

 district, which are themselves highly metamorphosed. 



2. ' The Geology of Monte Chaberton.' By A. M. Davies, Esq., 

 B.Sc, P.G.S., and J. W. Gregory, D.Sc, F.G.S. 



The importance of the Chaberton district, as affording a key to 

 the general geology of the Cottians, is explained, and the opinions of 

 previous observers referred to. The mountain was examined from 

 three sides — that of the Grand Vallon; the approach from Mont 

 Genevre by the Col de Chaberton; and that of the Clos des Morts 

 Valley. The following are the conclusions arrived at : — 



(1) The well-known Chaberton serpentine is intrusive into the 

 calc-schists, and yields fragments to the cargneules of the Trias : it 

 is therefore a pre-Triassic intrusion. 



(2) There are on the mountain other fairly basic schistose rock 



