GNEISSES IN THE COTTIA.N SEQUENCE. 



257 



Vol. 50.] 



The evidence of this exposure is unquestionable. There can be 

 no doubt of the iutrusive character of the dykes, nor that these are 

 composed of an acid rock in which all gradations can be traced from 

 a compact aplite or granulite to a fairly coarse, well-foliated gneiss. 

 It appears that the d\kes are an offshoot from a large mass below, 

 which has not been exposed ; its existence can be inferred from the 

 elevation of the overlying beds into an anticlinal, as is shown by the 

 photograph here reproduced. 



East of the exposure which has just been described, along the 

 path through Angrogna to Torre Pellice, the beds all consist of the 

 ordinary mica-schist, dipping south-east. 



Kg. 9. — Veins of gneiss {ajjlile) in the ' j>ietre verdi ' series, 

 Angrogna Valley. 



I -^ -•- ... »■-- ..****• -' 











* ;■ ' 







_^» ..**& _ Sow! 





^S^^^-'-^^^lU- 'fat 





. . . ■■■" 







The aplite- veins run obliquely upward across the right-hand lower corner ; one 

 occurs just above the lower margin and below the oblique series. 



5. The Pellice Valley. — According to Zaccagna's description and 

 map, 1 the ' central gneiss ' crosses the Pellice Valley near Bobbio 

 Pellice ; it occupies the area between the Rio Subiasco and the Bio 

 Cruello, the town being on the eastern margin. At Bobbio the main 

 valley is occupied by moraine, and the hill-slopes are so wooded 

 and cultivated that no exposures could be found ; to the west, how- 

 ever, a small footpath (named the Via Podio) branches from the 

 Villanova bridle-path and ascends through some orchards to the 



1 'Sulla Geologia delle Alpi accidental!,' Boll. R. Com. geol. Ital. vol. xviii. 

 (1887) p. 384, pi. xi. 



