306 MESSES. A. M. DA VIES AND J. W. GEEGOEY [Aug. 1 894, 



Michelotti's figures (op. jam cit. pi. i. fig. 2), and the septa in a 

 weathered specimen collected by us (Brit. Mus. No. R. 2374) in the 

 valley of the Clos des Morts. 



Calamophyllia fenestrate,, Reuss, is the typical species of the Gosau 

 Beds, and it is therefore interesting to find that we are driven to the 

 same conclusion by the study of the coral as that which Neumayr 

 reached from the examination of Michelotti's gasteropoda. We 

 are quite conscious that to maintain the existence of Cretaceous 

 deposits in the Western Alps is a reactionary step, especially in view 

 of Kilian's 1 recent refusal to admit any of the Monte Chaberton 

 limestones as later than Jurassic, and Dr. Diener's 2 apparent re- 

 tractation of this view in a recent letter ; he had previously accepted 

 it, and claimed that the fact " was the most remarkable phenomenon 

 in the geological structure of the Western Alps." 3 Our profound 

 faith in the late Melchior Neumayr's soundness of judgment and 

 especial qualifications for expressing an opinion on this subject had 

 been somewhat shaken by Kilian's doubts. The field evidence, 

 however, has clearly shown that the coralline and shelly limestones 

 are certainly post-Triassic ; whereas Kilian's view seems to be 

 based on the correlation of these beds with those near Oulx, which 

 have yielded the Myoplwria described by Portis. 4 The latter 

 horizon is unquestionably rightly assigned by Portis to the Trias : 

 the D/pfo^orafHchafh^non Young, i.e. alga, non bryozoon) associated 

 with the Myophoria settle that point; but this bed is the represen- 

 tative of the Gyroporella-limestone at the base of the Chaberton 

 series, and not of the limestones faulted down into the dolomites. 



The question then arises, is this band of limestone the only 

 representative of the Cretaceous in the Cottians ? We think not, for 

 the Yermanagna limestones must belong to the same horizon as those 

 at Chaberton. A third representative is more doubtful, but judging 

 from Kilian's 5 description of some limestones from Dorgentil, south 

 of Moutiers, we should not be surprised if they also have gained 

 their association with Jurassic deposits only by later dislocations. 



We had thus determined the first of the two problems for which 

 we had visited Monte Chaberton, for by proving that the coralline and 

 shelly limestones are not part of the dolomite series, and are probably 

 of Cretaceous age, a fairly complete time-scale has been established. 



Let us next consider the relations of the associated igneous 

 rocks to the various divisions of this time-scale. 



The views held as to the nature and ages of these rocks are very 

 varied. Those who regard them as metamorphosed sediments 



1 W. Kilian, 'Notes sur l'histoire et la structure geologique des Chaines alpines 

 de la Maurienne, du Brian<;onnais et des Regions adjacentes,' Bull. Soc. geul. 

 France, ser. 3, vol. xix. (1891) pp. 618-620. 



2 Quoted by Kilian, ibid. p. 620. 



3 K. Diener, ' Der Grebirgsbau der Westalpen,' p. 19. 



4 A. Portis, ' Nuove localita fossilifere in Val di Susa,' Boll. R. Com. geol. 

 Ital. vol. xx. (1889) p. 175. 



5 W. Kilian, ' Sur le Lias de la Savoie,' Bull. Soc. geol. France, ser. 3, 

 vol. xix. (1890), Cpt. Rd. Seances, p. xxvi. 



