Dr. Du Riche Preller—Crystalline Rocks, N. Prémont. 309 
peridotites, lherzolites and associated euphodites of the eastern or 
mica-schist horizon. In neither horizon do the euphodites appear as 
deep-seated rocks; they are, on the contrary, associated and inter- 
stratified with the other pietre verdi at all levels, overlying and 
underlying, and intercalated in them and the crystalline sedimentary 
schists quite as often as vice versa. As in the areas of the Maritime 
and Cottian Alps previously described, so also in the Lanzo valleys 
the pietre verdi constitute two distinct, juxtaposed, and eminently 
magnesian series of eruptive and submarine origin, contemporaneous 
respectively with the Mesozoic calc-schist and the Permo-Carboni- 
ferous mica-schist formations with which they are intimately 
associated, and jointly with which they have for long periods been 
subjected to repeated earth- HOVERS, folding, and intense pressure-, 
heat-, and hydro-metamorphism.! ° 
2. The Gran Paradiso Massif (Fig. 1).—This oval-shaped complex, 
about 30 by 20 kilometres in length and width, is bordered on the 
_ south by the Lanzo valleys and on the north by the Dora Baltea 
watershed. At its southern extremity it is traversed by the Val 
Grande Stura already referred to, while its central part is intersected 
west to east by the Orco, which rises in Punta Galisia (3,345 m.) and 
with its affluent the Soana discharges into the Po. In the northern 
part rise the Cogne and Savaranche torrents, both of which drain into 
the Dora Baltea near Villeneuve, above Aosta. ‘The Orco Valley has 
cut the original dome-shaped massif into two more or less parallel 
ridges, the southern from the treble-peaked Levanna to Monte Tovo 
(2,575 m.), and the northern which, starting from Punta Galisia, 
culminates in the classic ellipsoid or flat cupola of Gran Paradiso 
proper (4,061 m.), the highest point of the Grajan Alps. 
The massif is composed of three more or less concentric masses, 
viz., a nucleus of primitive, granitoid, porphyroid, glandular, and 
eye-gneiss with large felspar crystals up to 10 centimetres, surrounded 
by an inner belt of smaller-grained, schistose, biotitic gneiss with 
green nodules, and an outer belt of mica-schist and minute gneiss, 
often with white mica. Of the biotitic gneiss a large lenticular mass 
in the primitive gneiss crops out at Ceresole (1,613 m.) in the upper 
Oreo Valley, between La Levanna and Gran Paradiso. In this, the 
central part of the massif, the gneiss is bedded horizontally as the 
practically undisturbed fundamental substratum ; only the outer belt, 
more especially at the southern extremity, has shared in the folding 
and dipping of the Lanzo Valley region.? In juxtaposition to the 
1 In a valuable memoir, ‘‘Contribuzione allo studio delle roccie a glaucofane, 
ete., Liguria e Alpi Occid.,’’ Boll. R. Com. geol., 1903, p. 255 et seq., 
S. Franchi has shown that the crystalline sedimentary rocks of the Piémontese 
Alps, such as silico-caleareous schists (diaspri), quartzites, cale-schists and 
limestone, mica-schists, phyllites, and minute gneiss, contain glaucophane, 
epidote, sismondina, zoisite, chlorite, albite, and other secondary minerals as 
the result of metamorphism of associated and intercalated eruptive material. 
* Novarese found a granite vein in a large erratic gneiss block near the Sea 
Glacier (2,500 m.) in the south-west corner of the Paradiso massif, which may 
therefore contain intrusive granite, like the Argentera massif in the Maritime 
Alps. V. Novarese, ‘* Rilevamento Valli Orco e Soana, Alpi Occid.’’: Boll. R. 
Com. geol., 1894, p. 215 et seq. A. Stella, ‘“Rilevamento Valle Gre) Alpi 
Occid.’’: ibid., p. 343 et seq. 
