44 Reports and Proceedings — Geological Socieh/ of London. 



(a) The andesitic dykes in the neighbourhood of Allen Crags and 



Angle Tarn. 



(b) The dykes of the spherulitic and felsitic group on Yewbarrow 



and High Fell. 



(c) The dioritic ('bastard granite') bosses of Peers Gill, Lingwell 



Crag, and Bursting Knotts, with their associated dykes. 



(d) The Eskdale Grranite, with the granite-porphyry dyke running 



from Great Bank to Wasdale Head and thence to Kirkfell 

 Crags. 

 ((?) The dolcrite dykes, having a general north-west to south-east 

 trend. 



The dykes of series (a) bear a very strong petrological resemblance 

 to the Borrowdale volcanic rocks, into which they were intruded. 

 Furthermore, they are weathered to much the same extent and have 

 developed the same secondary minerals, among which- epidote is 

 conspicuous. They appear to the author to be of Borrowdale age, 

 and roughly contemporaneous with the lavas and ashes into which 

 they are inti'uded. The spherulitic and more acid series (b) are 

 considered to be also of Borrowdale age, though probably somewhat 

 later than the andesitic series. The rocks of the dioritic group (c) 

 are considered to be the holocrystalline and hypabyssal equivalents 

 of the Borrowdale Lavas, and the author is of opinion that they also 

 are of Ordovician age. 



The Eskdale and Wasdale Granites (d) are much more acid, and 

 show little sign of alteration except that due to weathering and 

 dislocation. They are undoubtedly intrusive into the Borrowdale 

 Series, but seem to be pre-Triassic. Thus the intrusion is probably 

 Devonian, like the neighbouring granite of Shap, which, with the 

 exception of its large phenocrysts of orthoclase, is not dissimilar to 

 some of the varieties of the Eskdale granite. The basic intrusions (e) 

 have only been examined where they come into proximity to the 

 granite. They may well be connected with the great Tertiai'y basic 

 flows of Antrim, as has been suggested by Mr. Harker. 



The granite becomes progressively more and more acid as its margin 

 is approached, until in some places the percentage of silica amounts to 

 96-16. This is explained by the assumption that the magma as 

 a whole was more acid than the eutectic mixture of quartz and 

 orthoclase, and that consequently the excess of silica separated in the 

 marginal portions, which were the first to solidify. 



December 2, 1908.— Professor W. J. 8ollas, LL.D., Sc.D., F.R.S., 

 President, in the Chair. 



The President announced that a Special General Meeting would be 

 held on Wednesday, February 10, 1909, in order to consider the 

 result of^ the vote of the Fellows on the question of the Admission of 

 Women into the Society. 



The following communication was read : — 



'• The Geological Interpretation of the Earth-Movements associated 



