62 ME. A. HAEKEE ON THE GEOLOGICAL [Feb. I906, 



contemporaneous vegetation swept down by a river of the pitchstone- 

 epoch and entombed in a river-gravel. On the interpretation put 

 forward in the present communication the question, how far the 

 wood is contemporaneous, how far derived in a fossil state from 

 older formations, is of secondary importance, but has a certain 

 interest of its own. Tertiary wood and coal, entangled even in 

 coarse volcanic agglomerates, are not uncommon in Skye and Canna, 1 

 and the Eigg wood may conceivably have a like mode of occurrence. 

 On the other hand, it is quite possible that fossil w r ood might be 

 derivative in the same sense as the fragments of sandstone with 

 which it is associated. Examining the question on the ground, 

 I inclined to this view so far as regards the greater part of the 

 wood; and various considerations go to support this opinion. 



It is to be noticed that three distinct kinds of fossil wood have 

 been mentioned above as occurring at this place : — 



(a) the black, mostly silicified, Finites eiggensis, embedded in the decomposed 

 base of the pitchstone as well as in the breccia, but evidently derived from the 

 latter source ; 



(b) the fragments of brown wood (Araucaroxylon, as noted below, p. 63) 

 associated with pieces of Oolitic sandstone in the breccia ; and 



(c) the wood associated with the sandstone of the breccia-horizon, and partly 

 occurring as a regular bed in that deposit. 



The last is manifestly contemporaneous with its matrix, and 

 therefore of Eocene age ; but concerning the other two kinds of 

 wood the two alternative explanations may be entertained. 



As regards the Pinites^ Mr. Seward informs me that it is 

 impossible to decide, from botanical evidence, whether it is of 

 Jurassic or of Tertiary age. The state of preservation, however, is 

 perhaps significant ; for British Tertiary wood is not in general 

 silicified, while that of Jurassic age frequently is. Wood is found 

 in place in the white Oolitic sandstones on Eigg itself. At Camas 

 Sgiotaig, a small bay near Laig, famous for its ' musical sand,' it 

 occurs in two varieties, as represented by Mr. Tait's collection : 

 (a) black and perfectly silicified ; (6) brown and ligneous, the 

 resemblance to the two corresponding varieties from beneath the 

 Sgurr amounting (to the eye) to absolute identity. It might perhaps 

 be suggested that the big log enclosed in the decayed pitchstone 

 derived its silica from the decomposition of that rock, and it is true 

 that the brecciated and decayed mass in this place sometimes 

 contains siliceous veins, like flint. But the character of the fracture 

 seen on the detached branches and the places where they have been 

 broken from the trunk is such as to suggest that the wood was 

 silicified before it was broken up. Neither Mr. Tait nor myself 

 could find any adherent matrix other than that in which the wood 

 now lies. Nevertheless, the association of this kind of wood with 

 that next to be noticed, both here and at Camas Sgiotaig, leads us 



1 An interesting early record is that in the old ' Statistical Account,' vol. xvii 

 (1794) p. 293, of a log of wood embedded in the coarse agglomerate of Alman, 

 on the eastern coast of Canna. 



