284 Geological Society : — 



January 22.— W. T. Blanford, LL.D,, F.R.S., President, 

 in the Chair. 



The following communication was read : — 



" On the Crystalline Schists and their relation to the Mesozoic 

 Rocks in the Lepontine Alps." By Professor T. Gr. Bonney, D.Sc, 

 LL.D., F.R.S., F.G.S. 



Tn the debate upon the paper " On two Traverses of the Crystal- 

 line Rocks of the Alps" (read Dec. 5, 1888) it was stated that rocks 

 had been asserted on good authority to exist in the Lepontine Alps, 

 which contained Mesozoic fossils, together with garnets, staurolites, 

 &c, and thus were undistinguishable from crystalline schists re- 

 garded by the author as belonging to the presumably Archaean 

 massifs of that mountain- chain. In reply, the author stated that 

 he regarded this as a challenge to demonstrate the soundness or un- 

 soundness of the hypothesis to which he had committed himself. 

 The present paper gives the result of his investigations, undertaken 

 in the month of July, 1889, in company with Mr. James Eccles, 

 F.G.S. , to whom the author is deeply indebted for invaluable help. 

 The paper deals with the following subjects : — 



(1) The Andermatt Section. 



By the geologists aforesaid, a highly crystalline white marble which 

 occurs on the northern side of the Urserenthal trough, at and above 

 Altkirch, near Andermatt, is referred to the Jurassic series (mem- 

 bers of which undoubtedly occur at no great distance, almost on the 

 same line of strike). The author describes the relation of the 

 marble to an adjacent black schistose slate, and discusses the signifi- 

 cance of some markings in the former which might readily be con- 

 sidered as organic, but to which he assigns to a different origin. He 

 shows that there are most serious difficulties in regarding these two 

 rocks as members of the same series, and explains the apparent 

 sequence as the result of a sharp and probably broken infold, as in 

 the case of the admitted band of Carboniferous rock at Andermatt 

 itself. That the section is a difficult one on any hypothesis the author 

 admits, but in regard to the former of these, after a discussion of the 

 evidence, he concludes " that tendered on the spot demands a ver- 

 dict of ' not proven ' — that obtainable in other parts of the Alps will 

 compel us to add, ' not provable.' " 



(2) The Schists of the Veil Flora. 



These schists, already noticed by the author in his Presidential 

 Address to the Society in 1886, occur in force near the Lago di 

 Ritom, and consist of two groups : — the one, dark mica-schists, some- 

 times containing conspicuous black garnets, banded with quartzites, 

 the other, various calc-mica schists ; between them, apparently not 

 very persistent, occurs a schist containing rather large staurolites or 

 kyanites. On the north side is a prolongation of the garnet-actino- 



