GEOLOGY OF THE WESTERN ALPS. 167 



known, but it is more specialised than any as yet known 

 from the Ordovician or Silurian. It may therefore show 

 that the schists are Devonian ; but no stress can be laid 

 upon the evidence as to age while the Palaeozoic radiolaria 

 are as imperfectly known as they are at present. 



Though, therefore, the gneisses are later than the 

 schists, this does not help us to assign any definite age to 

 them. For a nearer approximation we have to rely on 

 indirect evidence, and notably on the relation of the 

 gneisses to the earth-movements of the district, and the 

 first appearance of fragments in the sedimentary series. 

 The latter only shows that the Waldensian gneisses are 

 pre-Pleistocene, while, if the evidence of Dr. Gianotti can 

 be fully relied on, the Paradiso gneiss was pre-Miocene. The 

 earth-movements, however, give more definite conclusions. 

 These can be classified into six series ; one of these is 

 known to be Miocene, and the Waldensian gneisses were 

 intruded later than this. To the east of the Cottian area 

 the Pliocene beds have been upraised to the height of over 

 1500 feet, so that great earth-movements in this area 

 happened in the Pliocene. There is, however, no evidence 

 to show to what extent these affected the line along which 

 the gneisses occur. The intrusion of the gneisses may 

 therefore have happened either in the Pliocene, or as the 

 last of the series of earth -movements which occurred 

 between the Middle and Upper Miocene, when the forces 

 that raised the Western Alps attained their maximum 

 intensity. The author therefore concludes that instead of 

 the so-called "central gneiss" of the Cottians being the 

 oldest rock in the district, and according to Gastaldi 

 possibly the oldest in Europe, it is, with the exception 

 of the Pliocene and the drifts, the newest rock in the 

 Cottians. 



The largest work issued during the year on the district 

 is a monograph by M. Termier on the massif of the 

 " Grandes-Rousses " (9). This group is situated on the 

 north side of the well-known pass of the Col du Lauteret, 

 opposite the principal mountain mass in France, and to the 

 east of the town of Grenoble. The massif consists of a 



