234 Reports and Proceedings — Geological Society of London. 



Tlie 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 Oberald road. Eead off from the northern side 

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

 limestone, etc. — Jurassic, (3) a little rauchwacke, (4) "sericitic" 

 gneiss. The next section (about 250 feet above the St. Gothard 

 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 Eeuss 

 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 be present, it is very thin and 

 shattered. At Realp, about 3f 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 Furka 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, the southern one can be traced right across the Pass, but the 

 extent of the other is not so clear. 



Examination of the marble mentioned above shows in all cases 

 that it has been considerably modified by pressure since it became a 

 crystalline rock. The author discusses the evidence of these sections, 

 and maintains that the hypothesis that the marble is an older rock 

 intercalated by thrust-faulting among Jurassic strata leads to fewer 

 difficulties than to consider it as belonging to the same system. 



In the latter part of the paper the results of a re-examination of 

 the ravine-section in the Val Canaria, and of some studies of the 

 south side of the Val Bedretto, are described, which, as the author 

 maintains, confirm the view already expressed by him, viz. that 

 the schists with black garnets, mica, kyanite, dolomite, and calcite 



