GEOLOGY OF THE WESTERN ALPS. 155 



The paper deals with two different areas — Altkircke on the 

 north of the St. Gothard Pass, and the Val Canaria and 

 Val Bedretto to the south of it. The southern area is the 

 more easily disposed of. It is described as affording 

 further evidence of the truth of Professor Bonney's view, 

 that the Swiss geologists have confused a set of Mesozoic 

 phyllites with a series of Archean schists. They therefore 

 maintain the Mesozoic age of the latter rocks. It will 

 simplify the question to leave the age of the schists un- 

 certain ; for to call them Archean introduces a theoretical 

 view which must be settled on general probabilities, and 

 cannot be definitely decided in the field in this area. But 

 with this reservation it is difficult to compare the arguments 

 used by Professor Bonney in his " Lepontine " paper and 

 Professor Heim's criticisms without feeling that the con- 

 clusions against which the former contended cannot be 

 accepted without much fresh evidence in their favour. 

 Professor Bonney now further supports his position, which 

 Professor Heim's criticism has really only strengthened. He 

 shows (i) that the dark-mica schist and black-garnet schist 

 of the south side of the Val Bedretto are the same beds as 

 those of the north side of this valley; (2) that these can be 

 shown on the ground to be continuous with the disthene 

 schists ot Nufenen ; (3) that as the Triassic rocks contain 

 fragments of the three rocks (dark-mica, calc-mica and 

 disthene schists) with which the garnet schists are inter- 

 stratified, these cannot be of Jurassic, but must be of pre- 

 Triassic age. Their exact age cannot be definitely decided. 

 But it must be admitted that Professor Bonney has proved 

 that they are older than the oldest fossiliferous rocks in the 

 district. 



With the other part of Professor Bonney's paper the 

 evidence is less satisfactory. The Altkircke marble occurs 

 in a series of Jurassic phyllites, and it is claimed by the 

 Swiss geologists to be, therefore, also Jurassic. Professor 

 Bonney, however, contends that it belongs to a much older 

 period. He describes the occurrence of several outcrops 

 of this marble in the Jurassics, and Dr. Stapff states that 

 there are many more. The evidence is admitted by Pro- 



