254 DR. J. W. GREGORY ON THE WALDENSIAN [May 1 894, 



south-eastern limit of the gneiss as crossing the main valley at the 

 confluence of the Balma and the Chisone ; we went for some little 

 distance beyond this point, and failed to find anything but the brown 

 mica-schists. If the gneiss does, however, occur, it cannot be con- 

 tinuous with that of the Bocciarda and the Pelvo, or we should have 

 seen it in our traverse to the north. Abundance of the gneiss, how- 

 ever, occurs on a talus slope to the south-west of Castel del Bosc, by 

 the first fork after crossing the Chisone, along the bridle-path leading 

 to the hamlet of Garner. Erratics of the same rock are found 

 on the grass slopes west of the summit of Punta Medio Muret, 

 and probably indicate its occurrence somewhere along the ridge 

 between this peak and Punta Raccias ; but a dense cloud pre- 

 vented any search for the rock in situ at this point. With these 

 exceptions the whole of the rocks crossed between Castel del Bosc 

 and Perrero were of the schist series, with intrusive amphibolites 

 and interbedded limestones and dolomites. The last are well seen in 

 some crags on the south-eastern ridge of Punta Medio Muret, between 

 the summit and the point marked 2001 metres ; the dolomite is 

 much contorted, and is associated with some mica-schists containing 

 enormous garnets. The actual summit of Punta Medio Muret is 

 made up of the gneissoid mica-schist which so often occurs in the 

 neighbourhood of the intrusive gneisses. Between Castel del Bosc 

 and Garner the schists have a prevalent east-and-west strike ; but 

 between Massello and Perrero the strike has worked round to 

 W. 30° N. 



Near Perrero occur several large beds of amphibolite, as at a crag 

 above Maniglia and east of Quin, which is apparently intrusive 

 along the strike. A similar rock, probably an epidiorite, is worked 

 for road-metal at a quarry \ kilometre east of Perrero. It occurs 

 here in a position on which Zaccagna has marked ' central gneiss.' 

 There did not seem to be any evidence of the existence of that rock 

 at this point. There is a good exposure of mica-schist, richer in 

 mica and paler in colour than is usual, at the sharp bend of the 

 road about 1 kilometre from Perrero ; here a foot-bridge crosses the 

 Germanasca and a bridle-path leads south to Grangette and Poet 

 Soprano, as far as which all the exposures noted were of the coarse 

 gneissoid mica-schist. Above the latter, large garnets become 

 abundant; farther up, where the path bends round the flank of 

 Bocca del Cavalupo at a part where it ruus level for some hundreds 

 of yards, there is an amphibolite which is clearly intrusive into the 

 gneissoid mica-schists. The path thence rises to the ridge between 

 Rocca Bianca and Bocca del Cavalupo, which it crosses by a col at 

 the height of about 2025 metres. 



Prom this point we kept south along the main ridge as far as 

 Punta Cornour. The whole line is marked by Zaccagna as ' central 

 gneiss,' and it is therefore advisable briefly to refer to the main 

 types of rocks which compose it. At the col between Bocca Bianca 

 and the Bocca del Cavalupo, the rock is a pure white, massive, 

 crystalline, saccharoidal limestone, which has been there quarried for 

 the kilometre-posts on the new military road. The limestone is 



