Vol. 50.] CRYSTALLINE SCHISTS IN THE LEPONTINE ALPS. 289 



is bounded on the southern side by a low mound-like shoulder, which 

 also runs up the mountain, and can be readily traced for a consider- 

 able distance. On the northern slope of tbis shoulder the phyllite 

 extends nearly to the flattened summit 1 ; then, after about 3 yards 

 of covered ground, comes a small outcrop of a fissile grey-coloured 

 marble (?), followed, after about a yard, by another small outcrop 

 of darker rock, which appears to me on the whole to present most 

 resemblance to a variety of the marble very much crushed. 2 



In the next 4 or 5 yards are outcrops of a rather micaceous rock, 

 very fissile and rotten, which I consider to be most probably also a 

 crushed and much decomposed variety of the marble. To it succeeds 

 an outcrop of a rock generally similar, but less fissile, and about 2 

 yards from that is an outcrop of a rock distinctly crystalline, at first 

 rather micaceous, afterwards quartzose. Rocks of a like character, 

 but rather more calcareous, can be traced for some little distance 

 down the hill, roughly on the same strike. To the last-named 

 outcrop follows the white marble which is quarried a little below 

 the line of the section. On its southern side this mass forms a low 

 cliff 3 overlooking a depression occupied by Jurassic rocks. 



I must refer once more to the marble of this quarry. The lower 

 and larger opening is 10 or 11 yards wide, across the strike ; 

 the excavation apparently being limited on both sides by a less 

 pure 4 and more rotten condition of the rock. The quarried marble 

 is very crystalline and occasionally is distinctly banded with seams 

 of mica, when it resembles locally some of the calc-mica-schist 

 which in other districts of the Alps forms part of the group of 

 crystalline schists. The rock has a ' slabby ' structure parallel to 

 the seams of mica, and the surface of the slabs is ' fluted.' These 

 structures and the general aspect of the marble produce the im- 

 pression that when it was subjected to pressure it had already 

 become a crystalline rock, and this impression is confirmed by the 

 examination of several microscopic sections. As described in my 

 last paper, 5 we can trace this shoulder of marble for a considerable 

 distance up the steep mountain-side, but the section to which I 

 must draw particular attention occurs about 250 feet above the 

 high road. 6 Starting northward from this shoulder of marble, 

 already mentioned, we cross, for about 40 yards (estimate), a 

 turf slope, on which chips of phyllite abound, together with 

 (apparently) small outcrops of the same. 7 Then we come to a 



1 I omitted to eater in rny notes the distance of this from the northern gneiss, 

 but I think the breadth of the phyllite outcrop cannot exceed 35 yards. 



2 The condition of both these rocks makes it impossible to speak positively 

 as to their nature. Here No. 3 of the remarks made in the Introduction (p. 286) 

 must be remembered. 



3 I halted here, because the grass was not yet mown on the ground below, 

 and the age of this part of the section is not disputed. 



4 It contains a fair amount both of mica and of quartz. . 



5 In which details of the microscopic structure of the marble are given, 

 Quart. Journ. Geol. Soc. vol. xlvi. (1890) pp. 193-196. 



6 See the upper part of fig. 1, p. 288. 



7 I examined this slope most carefully, and was convinced that the phyllite 

 is in situ. 



