JPfofessof Boniiei/ — -Plant-steim in Gneiss. 217 



erratic blocks, incliuling that from whicli the Berne speciraen was 

 said to have been taken. 



This tiekl work ^ and subsequent microscopic study of specimens 

 strengthened my conviction that the rock was an ' arkose ' of 

 materials from crystalline rocks, and thus only an imitation of a 

 gneiss. - I may add that the other possibility — that these objects 

 were not really plants, but imitative markings, produced by earth 

 movements in a truly crystalline rock— had been present to my 

 mind throughout. It would have saved me from wasting my time 

 by a journey to Guttannen, so that, if I could, I would gladly 

 have adopted it. But the markings were accejited as plants by 

 the experts of the Swiss Survey,^ and, so far as I could form an 

 opinion, on good grounds, while the clastic structure of the rock 

 on the whole appeared to be original rather than superinduced. 

 Moreover, the grounds on which Herr Schmidt claimed the rock 

 for a true gneiss appeared to me, as I pointed out in my paper,* 

 defective in more than one respect. 



Still, though this visit to Guttannen strengthened my conviction, 

 microscopic study of the specimens did not, as I had hoped, place 

 the matter beyond all question. So in the Summer of 1895 I again 

 visited Guttannen, this time in company with my friend the 

 liev. Edwin Hill, F.G.S., and now more especially examined the 

 western flank of the valley. Everywhere the so-called Carboniferous 

 gneiss had a grit-like aspect, including a not unfrequent change 

 in coarseness perpendicular to the occasional banded structure. In 

 one place we found a thin band of rock resembling a dark phyllite, 

 but no conglomerate. We traced the ' Carboniferous gneiss ' 

 northwards nearly up to its junction with the ordinary gneiss of 

 the district, the difference between them being very marked. 

 Though the field work strengthened me in the view which I had 

 already expressed, complete demonstration was again wanting 

 and was not supplied by a microscopic study of the specimens 

 collected. Among other things, the supposed phyllite band exhibited 

 such indications of crushing as to make it an untrustworthy witness. 



I determined, however, to make a third attempt to obtain 

 decisive evidence. According to the Swiss geological map this 

 zone of 'Carboniferous gneiss ' crosses the Urbach Thai, just about 

 the foot of the Gauli Glacier. So in the Summer of 1897 I planned 

 a visit to this locality in company with Mr. J. Parkinson, F.G.S. 

 The walk to the foot of the glacier, from Im Hof, the nearest 

 halting-place, and back, takes about eight hours, so our time for 

 studying the gneiss was rather limited. The result of this ^ 

 and of subsequent microscopic examination of specimens was 



' About a month later I visited Vernayaz to look once more at the well-known 

 .Carboniferous infold, parts of which sometimes curiously resemble crystalline rocks ; 

 this time examining it as far as tlie Tete Noire. 



' This conclusion and the reasons are fully stated in a paper (Quart. Journ. Geol. 

 See., vol. xlviii, p. 390). 



^ Beitriige, ut supra, pp. 164-8. 



* Ut supra, p. 395. 



* On another day we spent a little time at Guttannen. 



