the Alps of Prémont and Savoy. 15 
TV. Tur PERMIAN IN RELATION TO ARCH#AN AND Mesozoic Scuists. 
Intimately connected with the stratigraphical position of the 
Permian is the demarcation of the Archzan and Mesozoic schists. 
As is well known, both Elie de Beaumont in the French map (1860) 
and Sismonda in the Italian map (1862) of the Western Alps divided 
the crystalline rocks into two great zones—a lower one, comprising 
indiscriminately the Archean gneiss, and the Paleeozoic and Mesozoic 
series, as the ‘‘ metamorphosed Jurassic area’”’; and an upper one, 
embracing the Archean granite and all the pietra verde rocks, as 
intrusive and post-Jurassic. The later maps of Lory and Favre of 
the French, and of Gastaldi of the Italian side, to some extent 
disentangled that strange confusion: Lory and Favre by assigning 
the gneiss, granite, and the ‘‘ vert des Alpes” to the Archean and all 
the mica- and cale-schists indiscriminately to the Trias as “ schistes 
lustrés’’, while Gastaldi separated all the pietra verde rocks into. 
a zone per se as overlying the primitive gneiss and granite zone, and 
labelled it and the mica- and cale-schists as crystalline rocks, more 
recent, but pre-Paleozoic. The Permian did not figure in any of 
those maps. 
Such was the position in the ’eighties when Zaccagna’s revisionary 
survey showed those more or less arbitrary classifications to be obsolete 
and untenable. Accordingly he defined the Archzean as composed of 
two zones—a lower, comprising exclusively the primitive gneiss and 
granite rocks, and an upper, embracing the mica-schists (schistes 
lustrés) and the small-grained tabular gneiss; the calc-schists and 
erystalline limestone; and the great masses of pietra verde as a con- 
temporaneous part.! From the Carboniferous formation, till then held 
- to be the only representative of the Paleozoic in the Maritime and 
Western Alps, he separated the Permian besimaudite and verrucano 
zone directly overlain by the indubitably Triassic series in which he 
included Lory’s ‘‘Lias compacte”’ or Brianconnais limestone. This 
clear definition of the Lower and Upper Archean, the Upper Paleozoic, 
and the Lower Mesozoic formations harmonized the two sides of the 
Western Alps, and was embodied in the new geological map of Italy of 
1896, a preliminary sketch of the earlier results in the Maritime and 
Cottian Alps having been already exhibited at the Berlin Geological 
Congress of 1885. These were largely, if with variations, adopted by 
Vasseur and Carez in their geological map of France of the same year.’ 
Zaccagna’s conclusions were thus, in the main, signally vindicated. 
1 The small-grained tabular gneiss (gneiss minuto tabulare) is extensively 
quarried in the Susa, Chisone, and Pellice Valleys for building purposes 
in Turin. 
2 Vasseur and Carez assign the crystalline schists west of Monte Viso on the 
Italian side to the Paleozoic (Cambrian), for which, however, there is no 
warrant, the absence of the Lower Paleozoic in the Western Alps being, on the 
contrary, an important feature as marking a long interval of erosion which led 
up to the Carboniferous formation, composed of the sedimentary and calcareous 
products of that erosion in which were engulfed the vast débris-accumulations 
of a luxuriant vegetation. The Archran age of the crystalline schists was, 
after Zaccagna’s publication in 1885, affirmed also by Professor Bonney (1886 
and 1889), in relation to the Alps generally. 
