14 Dr. Du Riche Preller—Permian in 
It then reappears— 
3. In Northern Piémont above Courmayeur, at the foot of Mont 
Blane, in the two well-known mountains Chétif and La Saxe (2,343 
and 2,358 metres), separated by the Dora Baltea, and again, some 
5 kilometres lower down the Dora Valley, in the Pian d’Arp, an 
eminence near Pré St. Didier. 
Throughout this more or less continuous belt from the Maritime 
Alps to Mont Blane the Permian exhibits the besimaudite and 
verrucano characteristics already described, and runs parallel with, 
and in normal sequence between, the Carboniferous and the Triassic 
series, so much so that the three zones, with the addition of a narrow 
Jurassic zone, all bifurcating at Col de Bonhomme, the south-western 
spur of Mount Bianc, form a belt, more or less interrupted by 
denudation, round that massif. 
Of the Permian outcrops, those of Modane and Courmayeur are of 
special interest: (1) that of Modane, because Lory and other French 
geologists included it in their great zone of crystalline metamorphosed 
‘Triassic schists, whereas its interposition between Carboniferous and 
Triassic—both fossiliferous—strata clearly proves its Permian age; 
and (2) that of Courmayeur, because Chétif and La Saxe were 
regarded as granitic spurs of the Mont Blanc massif,’ whereas 
Zaccagna recognized them as the northern extremity of a Permian 
synclinal fold, which is conformably overlain by the Triassic series, 
and whose southern extremity is the outcrop of Pian d’Arp near 
St. Didier, already mentioned. It appears again in the St. Mary 
Mountain near Aosta, some 20 kilometres down the Dora Valley. 
In Savoy the Permian zone from the Arc Valley at Modane to the 
Doron Valley south-east of Moutiers has more recently been considerably 
enlarged by Termier, more especially in the Vanoise region and in 
the Doron Valley itself.2 In Dauphiné the crystalline schists of 
Mont Genévre near Briancon have also been assigned to the Permian, 
whereas this formation only skirts the western base of that group, 
and is overlain by dark, indubitably Triassic limestone corresponding 
to the grezzoni of the Apuan Alps, while the crystalline schists with 
their diabasic and serpentinous (pietra verde) intercalations are clearly 
Archeean.? 
verde or vert des Alpes intercalations, surrounded by a Triassic belt. The 
former outcrop was regarded by Bertrand as Liassic, while Professor Lory 
included it in his Triassic metamorphosed schistes lustrés, and lastly, Zaccagna 
recognized it as schistes lustrés but of Archean age, the pietra verde intercala- 
tions being conclusive evidence by analogy with Mont Genévre, Susa, etc. 
Professor Gregory, in his searching analysis of all the evidence (Q.J.G.S., 1896, 
pp. 1-16), concludes in favour of the pre-Carboniferous age of the Mont Jovet 
schists, viz. in the absence of the Lower Paleozoic, virtually in favour of their 
Archean age. 
1 The Val Veni depression between these two mountains and the granite 
massif of Mont Blane is filled with Liassic limestone resting conformably 
against,the Permian of the former but unconformably against the latter. 
2 ‘* Btude sur la constitution géologique du massif de la Vanoise’’: Bull. 
‘Carte géol. France, vol. ii, No. 20, 1891. 
3 A sketch-section of part of the Mont Genévre group is given in Professor 
Bonney’s paper, ‘‘ Two Traverses of the Crystalline Rocks of the Alps’: 
Q.J.G.S., 1889, p. 80. The limestone at the western end is marked Jurassic, 
probably on the strength of Lory’s map as Lias compacte or calcawe 
Brianconnais. It is now included in the Trias. 
