234 DR,J. W. GUEGORY ON THE WALDENSIAN [May 1894, 



Plateau of France, Britunny, and the Western Alps (Oisans), iu 

 Switzerland as at the Simplon, in Spain as in Cantal, in Germany 

 as in the Eulengebirge and the Oberpfalzerwaldgebirge, and also 

 in Canada. The same series, basal gneisses, then coarse gneissoso 

 mica-schists with amphibolites and upper less foliated schists and 

 phyllites, can be followed even farther than M. Michel-Levy has 

 done; it occurs in China, as described by Richthofen, 1 and more 

 recently by Velain, 2 who has pointed out the dose resemblance of 

 the gneiss to that of the Simplon. In Brazil the same sequence 

 occurs, on the authority of Hartt 3 and Sterry Hunt ; in Tasmania, 

 as described by Thureau 4 ; in India 5 it is represented in the Sub- 

 Himalaya by the central gneiss, the gneissose schists and foliated 

 slate series, while in some places, as around Sikkim, the middle 

 member of the ' Baling ' series contains many hornblendic schists. 

 In Scandinavia occurs the similar sequence of 'jern gneiss' (with 

 magnetite), and 'gneiss gris a grenat,' or common gneiss with am- 

 phibolites, with overlying phyllites ; in Finland the succession is 

 the same, and Lucas 6 compares it with that established by Profs. 

 Giimbel, Groth, and Bonney in Saxony, the Vosges, and the Alps 

 respectively. 



In all these localities the sequence is fundamentally the same, the 

 only variation being in the position of the amphibolites, though 

 these are always confined to the two upper divisions. 



While the accepted theory of the structure of the Cottians num- 

 bered among its advocates practically all recent writers on the 

 subject, and as it was in harmony with this almost world-wide 

 sequence, it appeared rash in the extreme to doubt its truth. Two 

 previous visits to the area and a study of its literature and maps 

 had, however, raised several difficulties which appeared insuperable. 

 If the gneiss were the oldest rock in the district, why had it escaped 

 the crumpling and contortion, the foldings and faulting to which 

 the other rocks have been so extensively subjected '? Why arc its 

 minerals so fresh when those of the schists around are so weathered 

 and altered? Why does it happen that the mica-schists near the 

 gneiss are generally so much coarser than at a distance, and so 

 frequently garnetiferous ? Again, if the gneiss is the oldest rock, 

 why have none of the intrusive sheets and dykes of serpentine and 

 amphibolites of the ' pietre verdi ' series ever penetrated it ? They 

 cut through all the other rocks, from the Mesozoic limestones to the 



1 F. von Richthofen, ' China,' vol ii. (1882) p. 7<J(i. 



2 Velain, ' Geologic de la Chine,' Bull. Soc. geol. France, ser. 3, vol. ix. 

 (1881) pp. 474-475. 



3 C. F. Hartt, ' Geology and Physical Geography of Brazil,' 1870, pp. 550- 

 551. 



1 Thureau, ' Tasmania —West Coast, Progress Reports of Mines, no. 2: 

 Mount Heemskirk and its Mineral Deposits and Mines,' Tasinaniau Pari. 

 Paners. 1881, no. 82; and Johnston, 'Geology of Tasmania,' 1888, p. 23. 



B Medlicott in ' Manual of Geology of India,' 1879, pt.ii. pp. 014, 6 16', 627. 



6 R N.Lucas, 'Notes on the Older Rocks of Finland,' Geol. Mag. 1891, 

 pp. 173, 174 ; see also Sederholin. ' Studien liber arehaischer Eruptivgesteine a us 

 dem sudwpstlichen Finn-land,' Tscbertn. Petr. u. Min. Mitth. vol. xii. (1891) 

 pp. 98-100. 



