300 PROF. T. G. BONNET ON MESOZOIC ROCKS AND [Aug. 1 894. 



mass of schist to the other, but think it needless to publish them. 

 The point of main interest is this — that a group of stratified 

 saccharoidal dolomites or marbles, very different in character from 

 the rauchwacke, is associated here, apparently in due sequence, with 

 schist indistinguishable from that in the Val Piora, and from some of 

 that in the Val Canaria ravine. A similar dolomite or marble is 

 interstratified in the Binnenthal with the dark-mica schists of that 

 locality, in which also the black-garnet schist occurs, and all these 

 rocks as a whole appear to me inseparable from the schists, generally 

 calcareous and micaceous, which extend along the Pennine range 

 far away to the west, by the districts of the Simplon, of Saas, and of 

 Zermatt, not to mention places yet more distant. 



From these and other investigations I draw the following con- 

 clusions and inferences : — 



(i) That the dark-mica schist and the black-garnet schists 

 (though the latter are less frequent and the minerals not quite so 

 large) on the south side of the Val Bedretto cannot be distinguished 

 from the rocks which bear those names on the north side of the 

 same valley. 



• (ii) That in the one case they are associated with much sacchar- 

 oidal dolomite or marble, in the other with calc-mica-schists and 

 some bands of marble. Of these rocks also hand-specimens might 

 be collected which very often would be indistinguishable. 



(iii) That in the latter locality thin bands of disthene-schist 

 (i. e. the two-mica-schist) also occur. These, however, I did not 

 see in the Campolungo district, but they exist farther west on the 

 Nufenenstock. 1 



(iv) Hence, if the schists north of the Val Bedretto (Val Canaria, 

 Val Piora, etc.) are Jurassic rocks, so are those south of the same 

 valley. 



(v) But the group of schists, etc., south of the Val Bedretto can be 

 traced westwards by the Nufenenstock and its vicinity to the 

 Binnenthal. The dark-mica schists maintain the same general 

 character; in the Nufenen district they are associated with black- 

 garnet and so-called disthene-schists, in the neighbourhood of Binn 

 with black-garnet schist and dolomitic marble. Hence these schists, 

 etc., are also Jurassic. 



(vi) But the rauchwacke (Triassic) in the Val Piora, Val Canaria, 

 at Airolo, on the Nufenen Pass, and in the Binnenthal contains 

 fragments of one or more members of this group of rocks, e. g. the 

 dark-mica-, the disthene-, and the ordinary calc-mica-schists. 2 



(vii) Hence these Jurassic rocks are pre-Triassic, which, as Euclid 

 says, is absurd. 



1 Quart. Journ. Geol. Soc. vol. xlix. (1893) p. 89. Very probably they do 

 exist about Campolungo : I speak only of what I have myself seen. 



2 It is true that I have not yet succeeded in finding the black-garnet schist : 

 but though to lay on the table a piece of rauchwacke containing this rock 

 would be tempting as a coup de theatre, I have never cared to spend much time 

 or go out of my way to search for it. When of three kinds of rock, inseparably 

 associated, two occur in a conglomerate or breccia, the positive argument resting 



