138 Reports and Proceedings — 



sequence) ; that its crystalline condition does not resemble that of 

 the schist-series, but is rather such as is common in a rock of its 

 age ; that it contains mica and other minerals of derivative origin, 

 and in places rock-fragments which precisely resemble members of 

 the Piora schist series. 



(b) The Val-Canaria Section. — This section, described by Dr. 

 Grubenmann, is discussed at length. It is shown that the idea of a 

 simple trough is not tenable, for identical schists occur above and 

 below the rauchwacke ; that there is evidence of great pressure, 

 which, however, acted subsequently to the mineralization of the 

 schists ; and that in one place the rauchwacke is full of fragments 

 of the very schists which are supposed to overlie it. 



(c) Nufenen Pass, etc. — Other cases, further to the west, are 

 described, where confirmatory evidence is obtained as to great 

 difference in age between the rauchwacke and the schists, and the 

 antiquity of the latter. The apparent interstratification is explained 

 by thrust-faulting. 



(4) Tlte Jurassic EocTcs, containing Fossils and Minerals. 



The author describes the sections on the Alp Vitgira, Scopi, and 

 the Nufenen Pass. Here indubitable Belemnites and fragments of 

 Crinoids occur in a dark, schistose, somewhat micaceous rock, which 

 is often very full of "knots" and "prisms" of rather ill-defined 

 external form, something like rounded garnets and ill-developed 

 staurolit.es. These rocks at the Alp Vitgira appear to overlie, and 

 in the field can be distinguished from the black-garnet schists. In 

 one place the rock resembles a compressed breccia, and among the 

 constituent fragments is a rock very like a crushed variety of the 

 black-garnet mica-schist. These Jurassic " schists " are totally 

 different from the last-named schists, to which they often present 

 considerable superficial resemblance ; for instance, their matrix is 

 highly calcareous, the other rock mainly consisting of silicates. 

 Some of the associated mica may be authigenous, but the author 

 believes much of it and other small constituents to be derivative. 

 There is, however, a mineral resembling a mica, exhibiting twinning 

 with (?) simultaneous extinction, which is authigenous. The knots 

 are merely matrix clotted together by some undefinable silicate, and 

 under the microscope have no resemblance to the " black garnets." 

 The prisms are much the same, but slightly better defined ; they 

 present no resemblance to the staurolites, but may be couseranite, 

 or a mineral allied to dipyre. Hence, though there is rather more 

 alteration in these rocks than is usual with members of the Mesozoic 

 series, and an interesting group of minerals is produced, these so- 

 called schists differ about as widely as possible from the crystalline 

 schists of the Alps, and do not affect the arguments in favour of the 

 antiquity of the latter. In short, they may be compared to rather 

 poor forgeries of genuine antiques. Incidentally the author's 

 observations indicate (as he has already noticed) that a cleavage 

 foliation had been produced in some of the Alpine schists anterior 

 to Triassic times. 



