258 Dr. Irving — On the Air oh Schists. 



were "indeterminable (unbestimmbare) but undoubted (unzweifel- 

 bafte) organic remains," ' tbe author appears to have been leaning 

 upon tbe ' broken reed ' of mere macroscopic observation. This also 

 gives way on a closer microscopic examination, as Prof. Bonney has 

 not much difficulty in showing. 



(5.) We have no right to assume, as the author does. 2 that the 

 calc-mica-schists are rocks " which were first dej)osited at the bottom 

 of the sea as limestones by the agency of organisms (durch Vermit- 

 telungvon Organismen)." The present writer has shown elsewhere 3 

 that such assumptions are unnecessary and highly improbable for 

 the crystalline marbles, calc-schists, and the quartzites of the oldest 

 series of rocks. They can be accounted for in a very different way. 

 A stratigraphical difficulty which such an assumption raises was 

 pointed out by Mr. Eccles in the discussion of Prof. Bonney's paper; 

 a difficulty which the present writer's own observations in the Alps 

 enable him thoroughly to appreciate. 



(6.) The inconstant relation of the dolomite, etc., to the schists 

 and gneiss of that region of the Alps, and the extremely fresh and 

 unaltered condition of the dolomite deprives it of all value as 

 evidence of the age of the schists in juxtaposition with which it is 

 accidentally found in the Yal Canaria section. 



(7.) In face of the evidence now to hand, it is impossible to recog- 

 nize such a succession as is implied in the following proposition : 4 — 

 " It is scarcely far from the truth, if in the original area of the 

 sedimentary trough (Mulde), the anhydrite and gypsum is regarded 

 as the deeper or older, and the argillaceous limestones as the upper 

 or younger portion." 



And a further difficulty arises when we attempt to plot out the 

 section as a ' Doppelmulde ' or double infold with a central anticlinal, 5 

 since there is no apparent symmetry between the two synclinals 

 which are supposed to have entrapped the two dolomite groups of 

 rocks. Moreover, the occurrence of the 2-mica schists (zone 7 of 

 Dr. Grubenmann's section) outside the supposed Doppelmulde is 

 strong evidence against the younger age of the same schists as they 

 occur in zones 2 and 5. 



(8, lastly.) The suggestion 6 that, "in those zones where the 

 dolomites and argillaceous limestones are mashed into one another, 

 the molecules in contact might, under enormous pressure, form 

 margarite and meroxene more abundantly and produce the 2-mica 

 schists," is seen to be worthless, from the fact that, while the 

 2-mica schists occur three times in the section, it is only in one 

 instance (zone 5) that they occur between the dolomite and the 

 supposed quondam limestones. And the further suggestion 7 that 

 the garnets may have been fabricated by the combining together 

 (Zusammenscharung) of molecules of silicates of lime and alumina 

 is still more improbable. Even if the schists could be shown to be 



1 Ibid. p. 19. 2 j^, pp- 24, 25. 



3 Chemical and Physical Studies, etc., pp. 7-13. 



4 Grubenmann, Ibid. p. 25. 6 Ibid. p. 25. 

 6 Ibid. p. 26. 7 ibid. p. 26. 



