Vol. XXVII. 

 191C 



J Armitagb, Plant Remains m Olivine-Basalf. 25 



on the underlying basalts. In describing the fossil wood, he 

 says : — " Some of the upper pieces (of the Eigg pine) we found 

 in contact with the decomposing trap . . . ; but the greater 

 number .... lay imbedded in the original Oolitic grit in 

 which they had been locked up." 



Sir Archibald Geikie (12), in 187 1, regarded the pitchstone of 

 the Sgurr as a succession of lava flows which covered up the 

 eroded surface of older basaltic outpourings. 



In 1865 he (13) had said : — "At either end of the long ridge, 

 this pitchstone is seen to lie upon a hollow eroded out of the 

 underlying level sheets of basalt and filled up with compacted 

 shingle. Among the rounded stones of this shingle-bed there is 

 an abundance of coniferous wood, in chips and broken branches, 

 yet so^well preserved that, when newly taken out and still damp, 

 it might be taken, but for its weight, for the relics of some old pine 

 forest buried in a peat-bog.*' 



Sir Archibald Geikie, then, believed the fossil pine-wood frag- 

 ments to be enclosed in what he regarded as a river-conglomerate 

 underlying the pitchstone of the Sgurr. 



He says in a note (12) that " the actual position of the wood, 

 however, in the breccia and conglomerates underlying the 

 pitchstone is beyond all dispute. I myself have dug it out of 

 the bed." 



Mr. Alfred Harker (14), in a paper recently written, does not at 

 all agree with Sir Archibald Geikie's interpretation of the matter. 

 He goes into the subject very fully, and, if his views are correct, 

 the process whereby the fossil wood arrived at its present position 

 is the result of such an interesting series of events that they are 

 well worth being reviewed. 



He regards the pitchstone that composes the Sgurr as intrusive 

 into the group of basalt flows underlying the breccia containing 

 the plant remains, while the breccia itself he considers a volcanic 

 agglomerate partly re-arranged by water action. This agglomerate 

 " consists chiefly of fragments of various sizes, with a smaller pro- 

 portion of matrix, which is not always of the same nature. Sandy 

 or basaltic (perhaps ashy) material may predominate, and there 

 may or may not be sufficient calcareous and ferruginous matter to 

 make a binding cement. The fragments are of red sandstone 

 and other Torridonian (Pre-cambrian) rocks and of (Tertiary) 

 basalt, the relative proportions of these two varying, though the 

 former element is always well represented. There are angular 

 blocks of Torridonian sandstone up to four feet in diameter, 

 besides smaller fragments. Some of the pieces of basalt measure 

 from one to two feet in^diameter, and they are mostly sub-angular 

 in shape. Of more local distribution in a recognizable state is 

 the soft Oolitic sandstone. Pieces of this are abundant in places, 

 generally in a crumbling condition, and the sandy element in the 

 matrix may be attributed to this source. Mingled with the frag- 

 ments of Oolitic sandstone are fragments of brown wood." 



