188 Reports and Proceedings — 



LL.D., F.E.S. ; Sir John Evans, K.C.B., D.C.L., LL.D., F.R.S. ; Prof. A. H. 

 Green, M.A., F.E..S. ; J. W. Gregory, D.Sc. : Alfred Harker, Esq., M.A. ; G. J. 

 Hinde, Ph.D.; T. V. Holmes, Esq.; W. H. Hudleston, Esq., M.A., F.E.S. ; 

 J. W. Hulke, Esq., F.E.S. ; Prof. J. W. Judd, F.E.S. ; Prof. C. Lapworth, 

 LL.D., F.E.S. ; E. Lydekker, Esq., B.A. ; Lieut.-General C. A. McMahon ; 

 J. E. Marr, Esq., M.A., F.E.S. ; H. W. Monckton, Esq., F.L.S. ; Clement Eeid, 

 Esq., F.L.S. ; F. Eutlev, Esq.; J. J. H. Teall, Esq., M.A., F.E.S.; Prof. T. 

 Wiltshire, M.A., F.L.S. ; Eev. H. H. Winwood, M.A. ; Henry Woodward, LL.D., 

 F.K.S.; H. B. Woodward, Esq. 



Officers: — President: Henry Woodward, LL.D., F.E.S. ; Vice-Presidents: Prof. 

 A. H. Green, M.A., F.E.S.; G. J. Hinde, Ph.D.; Prof. J. W. Judd, F.E.S.; 

 E. Lydekker, Esq., B.A. Secretaries: J. E. Marr, Esq., M.A., F.E.S. ; J. J. H. 

 Teall, Esq., M.A., F.E.S. Foreign Secretary: J. W. Hulke, Esq., F.E.S. 

 Treasurer: Prof. T. Wiltshire, M.A., F.L.S. 



TIL — February 21st, 1894. — Dr. Henry Woodward, F.E.S., 

 President, in the Chair. The President announced that the Sixth 

 Session of the International Geological Congress will be held at 

 Zurich from August 29th to September 2nd, 1894. The meetings 

 are to be divided into three sections : — 



1st. General Geology, etc. 



2nd. Stratigraphy and Palaeontology. 



3rd. Mineralogy and Petrography. 



Geologists having papers to present at the meetings are requested 

 to notify the same to the Committee, and to send a short abstract 

 of the subject with which they propose to deal. The Circular is 

 suspended on the Notice-Board at the Apartments of the Society 

 for the convenience of those Fellows who may desire further 

 information. 



The following communications were read : — 1. "On the Relations 

 of the Basic and Acid Rocks of the Tertiary Volcanic Series of the 

 Inner Hebrides." By Sir Archibald Geikie, D.Sc, LL.D., F.R.S., 

 F.G.S. 



After an introductory sketch of his connection with the inves- 

 tigation of the Tertiary volcanic rocks of Britain, the author 

 proceeds to describe the structure of the ground at the head of 

 Glen Sligachan, Skye, which has recently been cited by Prof. Judd 

 as affording inclusions of Tertiary granite in the gabbro, and as 

 thus demonstrating that the latter is the younger rock. He first 

 shows that the gabbro, instead of being one eruptive mass, consists 

 of numerous thin beds and sills of different varieties of gabbro, 

 some of which were injected into the others. These various sheets, 

 often admirably banded, can be seen to be truncated by the line of 

 junction with the great granophyre-tract of Glen Sligachan. A large 

 mass of coarse agglomerate is likewise cut ofi' along the same line. 

 These structures are entirely opposed to the idea of the gabbro being 

 an eruptive mass which has broken through the granophyre. They 

 can only be accounted for, either by a fault which has brought the 

 two rocks together, or by the acid rock having disrupted the basic. 

 But there is ample evidence that no fault occurs at the boundary-line. 



The granophyre becomes fine-grained, felsitic, and spherulitio 

 along its margin, where it abuts against the complex mass of 



