258 DE. J. W. GREGORY ON THE WALDENSIAN" [May 1 894, 



north. Five minutes' walk along this, in a field north of the 

 path, there is an exposure of a pale-coloured, foliated, fine gneiss. 

 The rock is worked here, and the quarry is known to the peasants as 

 the ' Rocca Bianca.' The actual junction cannot be seen, but brown 

 mica-schists can be found at a little distance above and below it. 

 The foliation dips about 20° west, and is approximately the same 

 as that of the surrounding schists. In the Cruello Valley there 

 are numerous blocks of gneiss scattered about the lower part of 

 the stream ; as this is followed to the north, the schists become 

 coarser and very contorted. The valley, however, is closed by two 

 vertical side-walls and a waterfall, which may mark the junction 

 with a northern mass of gneiss. But the path towards Malpertus shows 

 only the ordinary mica-schists, and the peasants whom I asked 

 could not tell me of any place where the gneiss occurred, except at 

 llocca Bianca ; and as they all immediately recognized the specimens 

 from that quarry, some value may be attached to their evidence. 



All, therefore, that can be safely asserted about the gneiss here is 

 that it occurs as a thin sheet or dyke, which is probably only an 

 offshoot from a mass to the north, between Bobbio and Cima 

 Chiapis, though it is possible that it is not at all or but slightly 

 exposed on the surface. 



A more extensive exposure in the Pellice Valley occurs on the 

 south bank east of Villar Pellice ; the rock is here a coarse augen- 

 gneiss, with the minerals as usual all strikingly fresh and pale. It is 

 worked in a number of quarries, the line of which is connected by a 

 series of crags which stand out above the soft schists and talus. 

 Being unfortunately compelled to leave the Pellice rather hastily, 

 we were unable to examine the field relations of this band of gneiss. 

 It must therefore be here also left doubtful whether the rock is 

 anything more than an intrusive sheet. The northern slopes of the 

 Pellice Valley all appear to be made up of the schist, and there is 

 therefore seemingly no connexion between the gneiss on the southern 

 bank of the Pellice and the outcrop in the Angrogua Valley. 



6. Barge.— Gastaldi has described the occurrence of the ' central 

 gneiss ' at Barge, and has inferred therefrom that it is a continuation 

 of the same rock seen farther west near Ostana, here brought up to 

 the surface by a fold. Zaccagna, however, whose Section II. crosses 

 the country a little north of this town, does not admit the 

 occurrence of the gneiss there. The rock is one of the pale-coloured, 

 coarse augen-gneisses, exactly similar to that which he has else- 

 where described as ' central gneiss.' The foliation dips S.W., as 

 does also that of the mica-schists which succeed it to the west : I had 

 not, however, the time to search for a junction, and indeed should 

 hardly expect to find one that would be at all satisfactory. 



After passing the 788 -metre point the schists dip eastward, but 

 they subsequently become horizontal, and at a sharp bend in the road 

 at the 833-metre level the schists are black and dip south-west. 



7. Crissolo. — Zaccagna's main section through the Cottians 

 crosses the valley of the Po at Crissolo and thence continues east- 



