Vol. 63.'] ATTRIBOTED TO THE SAVOY AND SWISS ALPS. 297 



it sometimes becomes friable under severe pressure, it is very dif- 

 ferent from the ' powdery ' rauchwacke which is occasionally found, 

 either alone or underlying dark schistose Jurassic rock, in this 

 region of the Alps, and can be readily distinguished from the pale, 

 buff-coloured, compact subcrystalline Triassic dolomites, so familiar 

 to travellers in the Southern Tyrol. It is, in short, the type of 

 rock which, whenever its stratigraphical relations are carefully 

 studied, is always found to be associated with true crystalline schists 

 of much greater antiquity than the Secondary Era. 1 The ' schistes ' 

 also in the same sections (with the possible exception of a small 

 portion on the northern flank of the Simplon section, which may 

 belong to a belt of schistose slate well known to me from outcrops 

 near the Pont Napoleon above Brieg and in one or two other places) 

 are members of a well-marked and readily-recognizable group 

 which can be traced along the Alpine chain (to speak only of what 

 I have myself seen) from Monte Yiso to the Gross Glockner. It is 

 generally more or less calcareous, passing often rather rapidly into 

 the above-named marbles, and sometimes (I think usually at its 

 base) into a quartz-schist. One or two bands rich in staurolites 

 occur, and the darker beds locally contain numerous black garnets ; 

 in short, this great ' calc-mica-schist ' group is, as I have elsewhere 

 pointed out, 2 later in age than the ordinary gneisses of the Alpine 

 region, but earlier than anything that can be dated. One by one, 

 the reference of these crystalline schists and limestones to Mesozoic 

 or later Palaeozoic ages has been shown on closer study to be 

 erroneous. 3 The constituents of these crystalline rocks in the 

 Simplon-Ofenhorn district though sometimes crushed by subsequent 

 pressure, are all authigenous, not less so than in a marble or a 

 schist which has been locally produced by contact- action from 

 sedimentaries of known geological age. That is to say, even 

 granting these two sections to be accurately represented so far as 

 the outcrops are concerned, the progressive overfolds exhibited by 

 them are only hypothetical, for they depend on an erroneous 

 identification of an important member. 4 



A third section may be briefly noticed, since it affords a typical 



. 1 See especially this Journal, vol. xlv (1889) p. 67, & vol. xlvi (1890) p. 187 ; 

 also Proc. Geol. Assoc, vol. xv (1897) p. 7. 



2 Quart. Journ. Geol. Soc. vol. 1 (1894) p-p. 297-301 & the papers just cited. 



3 The Swiss geological maps still permit an ' alternative ' existence to one 

 group in the neighbourhood of Zermatt. Knowing its members well, I can 

 only wonder on what grounds their Mesozoic age was asserted. Its advocates 

 will perhaps call upon the Carrara marbles for support. Of these also I have 

 some personal knowledge, and venture to say that when this region is studied 

 by a petrologist accustomed to work in the field, we shall hear little more of 

 identification with deposits of either Triassic or Carboniferous age. 



4 More than one of the authors whom I have named above, as generally 

 supporting Prof. Lugeon's views, assume the crystalline limestones to be Triassic, 

 and confuse under the one name — schistes lustres — the two types of rocks 

 which I maintain to be distinct in character and widely different in age. As 

 their sections and interpretations depend on these fundamental errors (as. I 

 deem them), I think it needless to say more than that I have not overlooked 

 their contributions to the literature of the subject. 



