208 



PKOF. T. G. BONNE Y ON CETSTALLTNE SCHISTS AND THEIK 





^ 





(b) Veil Canaria Sectmi, . 



A little west of the district 

 just described is the Val 

 Canaria with the noted sec- 

 tion described by Dr. Gru- 

 benmann. His memoir is a 

 careful and elaborate study 

 in petrography, so that I may 

 pass over the minor details 

 and confine myself to the 

 petrology — that is, to the 

 inductive treatment of these 

 details — where I cannot say 

 that the author appears to 

 me to have been equally suc- 

 cessful. This section, as Dr. 

 Grubenmann states, is best 

 seen by climbing up a ravine 

 which runs roughly from 

 north to south *, and has 

 been excavated by a small 

 stream descending from the 

 Alpe Pontina to the lower 

 part of the Val Canaria. 

 Here, on either side of the 

 ravine, is a considerable mass 

 of rauchwacke, with gypsum 

 or anhydrite and some dolo- 

 mite (fig. 5). Above this a 

 thick mass of various schists 

 is ascended, and then comes 

 another thick mass of rauch- 

 wacke &c. followed by a small 

 zone of schists similar to some 

 of those below ; above which 

 we find representatives of 

 the Tremola schist and the 

 gneiss f. According to Dr. 



"^ It is not a very easy climb in 

 all parts. More than once, if we 

 had not had our ice-axes to chip 

 an occasional step in the debris, we 

 should have had to make a detour. 



t Thus far the section drawn by 

 Mr. Eccles and myself agrees with 

 that given in general terms by Di*. 

 von Fritsch, and in greater detail 

 by Dr. Grubenmann. Between our 

 own section and that of the latter 

 are some slight differences of detail, 

 but they are insignificant ; and as 

 we went only once up the ravine 

 (and the work is not easy) lie may 

 be more correct than ourselves. 



