562 Dr. Du Riche Preller — The Carrara Marble District. 



Subsequently, in 1883 and 1885, Zaccagna, who at that time surveyed 

 both the Grajan and the Western Maritime Alps on the Italian side, 1 

 showed conclusively that not in the former (nor in the St. Gothard 

 schists), but in the latter is found the analogy with, and the 

 equivalent of, the Apuan central schists, the uniform parallelism of 

 the schists and the overlying grezzoni being in both cases precisely 

 the same. Moreover, the fossils found in the Maritime Alps, notably 

 in the Tanaro valley, were confirmed by Professor Portis 2 of Pisa as 

 indubitably Upper Palaeozoic, and hence it is due to Zaccagna that the 

 long debated age of the Apuan central schists was finally determined 

 as Lower Permian. 3 



Between the Permian and the Upper Triassic schists there is a very 

 essential difference. Apart from their totally different stratigraphical 

 position, the Permian schists are distinguished by their dark and 

 predominantly gneissose, the Upper Triassic schists by their lighter, 

 essentially micaceous and lustrous, sericitic texture. On the eastern 

 side of the range, the upper schists often pass into so-called 

 pseudomacigno sandstone ; it is only on the western side that they 

 are more crystalline, sericitic, and chloritic, and, owing to minute 

 quartz nodules, sometimes simulate a gneiss-like appearance. In the 

 extremely rare cases where the lower and upper schists appear in 

 juxtaposition, e.g. for a short instance near Canevara in the Frigido 

 valley (Massa), owing, not to any faulting, but to the lenticular 

 thinning out of the normally intermediate strata, they graduate into 

 each other. The Permian schists, moreover, nowhere — except in 

 a similar case of lenticular thinning out in the Arni region — are seen 

 in direct contact with the principal marble zone, whereas the Upper 

 Triassic schists are frequently associated with the marble of the 

 upper and also of the principal zone. This intimate association of 

 all the members of the Triassic series, their constant alternation, 

 thinning out — sometimes completely — and compensating each other, 

 and the consequent absence of faulting, constitute indeed the great 

 characteristic feature of the lenticular structure of that Apuan 

 formation. 



The maximum outcrop of the Permian schists occurs in the middle 

 part of the Prigido valley (Massa), whence they extend south-east 

 to the Stazzema division, north-west to Monte Sagro and beyond, 

 and east to Monte Tambura and the Arni region. The Upper Triassic 



1 "Alpi Graje": Boll. K. Com. Geol., 1892, p. 322. " Alpi Occidentali 

 (Marittime) " : ibid., 1887, p. 416. 



2 "Piante fossili Valle Tanaro, Alpi Marittime": ibid., 1887, p. 417. 

 The fossils of the Middle Trias grezzoni were determined by De Stefani, 

 P.V.S.T. Sc. Nat., vol. 1880; tbose of the Upper Trias series by Meneghini, 

 "Fossili Triassici Alpi Apuane " : ibid., vol. v, p. 693; and by Canavari, 

 ibid., vol. v, p. 184. Tbus, tbe palseontological evidence of tbe Apuan Alps is 

 practically complete. The best palseontological and penological collection of 

 tbe range, apart from tbe local one of Carrara, is that of tbe University of Pisa. 



3 Tbe present writer proposes to deal more fully in a future paper with this 

 Lower Permian formation as distinguished from tbe Upper Permian verrucano 

 formation. Tbe Permian range of tbe Maritime Alps forms tbe divide between 

 Soutbern Piemont and tbe Italian Eiviera, known as tbe Montgioje Mountains, 

 where tbe Tanaro, an affluent of tbe Po, has its source. 



