﻿L «1 ] 

 L. Proceedings of Learned Societies, 



GEOLOGICAL SOCIETY. 

 [Continued from p. 245.] 



April 11th, 1894.— Dr. Henry Woodward, F.R.S., 

 President, in the Chair. 



THE following communications were read : — 

 1. ' Mesozoic Rocks and Crystalline Schists in the Lepontine 

 Alps.' By T. G. Bonney, D.Sc., LLJ)., P.R.S., F.G.S., Professor of 

 Geology in University College, London, and Fe^ow of St. John's 

 College, Cambridge. 



The author described the results of an examination of the infold 

 of Jurassic rock in the Urserenthal, undertaken in the hope of 

 finding some definite evidence as to the relations of the marble, 

 exposed near the old church at Altkirche, and the adjacent Jurassic 

 rocks. Good sections are few and far between ; for the comparatively 

 perishable nature of the rock causes it usually to be masked by 

 debris and turf. 



The easternmost of the sections described occurs high up on the 

 slopes north of the Oberalp road. Read off from the northern side 

 it exhibits (1) gneiss, (2) phyllites with bands of subcrystalline 

 limestone, etc. — Jurassic, (3) a little rauchwacke, (4) 'sericitic' giie'ss. 

 The next section (about 250 feet above the St. Goihard road at 

 Altkirche) gives (1) gneiss, (2) covered ground, (3) slabby marble, 

 (4) phyllite, (5) thicker mass of slabby marble, (6) phyllite, etc., 

 (7) ' sericitic ' gneiss. The third section (just above the church) 

 runs thus, using numbers to correspond with the last : — (1) gneiss, 

 (4) phyllite, (5) slabby marble, (6) phyllite, etc., (7) ' sericitic ' 

 gneiss. It must be remembered that on the slopes of the Oberalp 

 farther south, between the • sericitic ' gneiss and the ' Hospenthal 

 Schists,' another dark phyllite is found, generally considered by the 

 Swiss geologists to be Carboniferous. The marble in the third section 

 is in places distinctly banded with white mica, and passes on the 

 northern side into fairly normal mica-schist and quartzose schist. 

 The fourth section, about a mile away, on the left bank of the 

 lleuss valley, gives a practically continuous section in phyllite and 

 dark limestone, without any marble. In the fifth section, rather 

 more than a mile farther, if any marble is present, it is very thin and 

 shattered. At Realp, about 3| miles farther, the next good section 

 is obtained. Here the rocks go in the following order (from the 

 northern side): — (1) gneiss; (2) phyllite and limestone ; (3) sub- 

 crystalline limestone, looking very crushed ; (4) the marble ; (5) 

 phyllite, etc. ; (6) Hospenthal Schists. The last group of sections 

 occurs near the Purka Pass. In the first, crossed by the high road, 

 there is no marble, but a little rauchwacke on the southern side. 

 The next one, on the slopes below the pass, seems to show two masses 

 of the marble parted by a subcrystalline limestone like that at 

 Realp, with phyllite above and below. Of the two masses of marble 



