.21,^ Professor Bonney — Plant-stems in Gneiss. 



.; The gneiss-plant's first introduction to English literature was, 

 I think, in 1890, when Professor Heim, in a controversial note 

 appended to my paper on "Crystalline Schists and tlieir relation 

 to Mesozoic Eocks in the Lepontine Alps," ' cited it as a pi'oof that 

 gneiss of Palgeozoic age existed in the Central Alps ; but it was 

 described and figured by Baltzer'^ two years earlier in the official 

 publication of the Swiss Geological Survey. I had, however, 

 exaniined the specimen when visiting the Museum at Berne in 

 August, 1889, and can best describe its aspect and the impression 

 it produced on me by an extract from my diary. " The rock 

 is a purplish-grey colour, rather fine-grained as a rule, containing 

 numerous small plates of brown mica, many white spots rather 

 angular in outline, apparently felspar, and quartz, in the matrix. 

 One or two quartz veins traverse the block. The rock at first sight 

 is wonderfully like a gneiss. It has evidently been compressed, 

 resulting in a sort of foliation or rude cleavage, with a brown 

 slickensided look on the surfaces of the supposed organisms (cf. the 

 Obermittweida conglomerate, Reusch's Scandinavian fossils in 

 Silurian 'schists,' etc.). The rock does not exactly resemble any 

 gneiss I have seen in the Alps. Though I cannot be quite sure that 

 I detected extraneous fragments, I thought I did. The matrix varies 

 somewhat from coarse to fine, as one traces it through the mass, and 

 its ultimate groundmass or ' paste ' has a slightly muddy look. 

 In short, the rock reminded me very much of some of the best 

 ' imitative crystallines ' of Vernayaz, and I suspect that it is really 

 an infolding of Palaeozoic or Mesozoic ' arkose.' The tree stems 

 are two in number', with obscure traces of what may be a third ; 

 the largest about 5 feet long by 8 inches wide ; it rises in a low 

 curve, with a sagitta of about 3 inches. There are some indications 

 of cross markings like the stems of calamites ; no ribbings or leaf- 

 scars that I noticed. In short, they are obscure markings, but 

 1 think it more likely that they indicate vegetable remains than 

 that the rock is a member of the crystalline series." The opinion 

 thus formed was expressed in a note on Professor Heiiu's comments 

 appended to the above-named paper.' 



I determined, however, to make a fuller investigation of the 

 question, and in 1891 found an opportunity of visiting Guttannen, 

 in company with my friend Mr. J. Eccles, F.G.S. On my way 

 from England I baited at Berne to make anotlier examination of 

 the specimen in the Museum. The :iote, written on the spot, is 

 practically an epitome of that already quoted, with the addition 

 that "one stem appears to have a kind of 'bark,' not graphite, but 

 dark carbonaceous matter, as if coaly material were mixed with 

 mud. The outer surface has a sort of brown glaze (irony) over it, 

 and so has the inner one." At Guttannen we examined the outcrops 

 of the supposed Carboniferous gneiss on the eastern side of the 

 valley, with some of those on the western, together with many 



^ Quart. Jouru. Geol. Soc, vol. xlvi, p. 237. 



2 Beitrage zur geol. Karte der Schweiz, Lief, xxiv (1888), pt. 4, p. 161. 



3 Quart. Journ. Geol. Soc, vol. xlvi, p. 238. 



MM 



