GEOLOGICAL HISTORY OF SERPENTINES. 183 
in 1871 and 1874, entitled Studii geologici sulle Alpi occidentali ; in a letter to de Mortillet in 
1872; in one to Zezi in 1876, and finally in one to Sella in 1877, with a postscript in 1878. * 
These various papers are illustrated with numerous maps, plans and diagrams. In 
attempting to gather from these sources a brief statement of Gastaldi’s conclusions as to the 
geology of the Alps and the Italian peninsula, I feel that Iam both rendering a veritable 
service to science and paying a tribute to the memory of my honored friend and correspon- 
dent of many years. ; 
§ 50. The Studii, ete., contain, besides Gastaldi’s own descriptions and sections, many 
important historical details and extracts from the literature of the subject. In the second 
part will also be found reproduced two engrayed sections, the one by Gerlach, from Monte 
Rosa, by Varallo and the Lago di Orta to Arona on Lago Maggiore, and the other by Carlo 
Neri, from the same point, in a course more to the south-eastward, by Valsesia, to 
Monte Fenera, and beyond.+ A comparison of these sections with those described by Gas- 
taldi, will be found of much value for the elucidation of the questions before us. Start- 
ing from the granitic gneiss of Monte Rosa (the central gneiss of von Hauer, and the ancient 
gneiss of Gerlach and Gastaldi) we find in Neri’s section a breadth of not less than seven kilo- 
meters included in the zone of the pietre verdi, and described as a stratified series of “ ser- 
pentines, talc-schists, etc.” followed by seven kilometers additional, designated as diorites ; 
the two being classed together as a “protozoic terrane.” To this succeeds a breadth of not less 
than fourteen kilometers occupied by what is described as a more recent crystalline ter- 
rane, conjecturally referred to the paleozoic period, and consisting of calcareous schists and 
quartzites, with mica-schists, and a great mass of intruded granite. Succeeding this is a 
great breadth described as porphyry or porphyritic conglomerate, followed by limestones 
and dolomites, all of which are referred to the trias, and appear in Mount Fenera, suc- 
ceeded by fossiliferous liassic and tertiary strata. 
The section by Gerlach, from Monte Rosa to Arono, shows above the ancient 
central gneiss a great breadth described simply as diorite, having at its base a thin belt 
of micaceous schists, and above it, between Varallo and the lake of Orta, a wide extent 
of recent gneiss and granite, followed, to the east of the lake, by gneissic mica-schists, suc- 
ceeded by porphyry, until we reach the dolomitic limestone at Arona. 
§ 51. Coming now to Gastaldi’s own sections, we have one from Turin passing west- 
ward to the French frontier, and crossing a broad mass of the central gneiss; to the west 
of which, in a distance of forty kilometers, we have, first, three and a half kilometers of 
euphotide and serpentine, followed by about the same breadth of mica-schists, calcareous 
schists and diorites, and finally, by a great extent of calcareous schists, with numerous 
intercalations of serpentine and, towards the summit, gypsum and dolomite. The less 

* Studii geologici sulle Alpi occidentali; memorie del Regio Comitato Geologico, vols. I and IT; Deux mots 
sur la géologie des Alpes cottiennes ; lettre à M. de Mortillet, Comptes Rendus de l’Acad. des Sciences de Turin, 
vol. vii, 28 avril, 1872; Lettere del Prof. B. Gastaldi all’ingegnere P. Zezi, Boll. del R. Com. Geologico, 1876; Sui 
rilevamente geologici fatti nelle Alpi Piemontesi durante la campagna del 1877, lettere del Prof. Gastaldi al Pre- 
sidente Quintino Sella ; Reale Accademia dei Lincei, memorie della classe di scienze fisiche, ecc. anno CCLXXYV., 
(1877-78.) See also the writer in his Report on Azoic Rocks, p. 245, and Chem. and Geol. Essays, pp. 336, 347. 
+ The section by Gerlach is probably from his Karte der Penninischen Alpen ; Nouy. Mém. de la Soc. Helvét. 
de Sci. Nat., 1869. That by Neri is from the Boll. del Club Alpino, vol. viii, No. 22, Torino, 1874, 
