President's Address. 23 



moiis differential pressure to which they were subjected, 

 they cannot be expected to yield distinct fossil forms. The 

 strata, however, are not all equally crushed. Quite recently 

 one of my colleagues — Mr Barrow — has obtained recognis- 

 able fossils like serpulites from ^he altered limestones of the 

 Perthshire Highlands, and has found worm burrows in the 

 quartzites. This discovery is of special interest, inasmuch 

 as it shows that the beds are noc utterly destitute of organic 

 remains, and it encourages the hope that still more definite 

 forms may be found. 



West of a line drawn from Loch Eribol to Skye, the 

 Archaean rocks lie beyond the area of the terrestrial move- 

 ments of post-Silurian time. In the Archaean series there 

 is little likelihood of organisms ever being found, for, so far 

 as my observations have gone, in the North-West Highlands 

 I have never seen a bed which could be regarded as of sedi- 

 mentary origin. Indeed, the gneisses all bear evidence of 

 having been formed by the crushing and recrystallisa- 

 tion of igneous rocks, their schistosity being due to mecha- 

 nical movement of the particles produced by differential 

 pressure. Between the formation of the Archaean gneisses 

 and the deposition of the Cambrian conglomerates and sand- 

 stones an enormous lapse of time must have intervened. 

 These sedimentary deposits might yield fossils, for, in certain 

 areas, they lie comparatively undisturbed. From the coarse 

 material of which they are composed, and the indications of 

 rapid accumulation, we may naturally infer that they repre- 

 sent a great lacustrine formation. For this reason it is not 

 probable that they will readily yield remains. There is 

 nothing unreasonable in the supposition that they may be 

 the equivalents of the Cambrian rocks of Wales, which have 

 afforded some of the oldest fossils yet known. A small out- 

 lier of these Cambrian rocks caps the headland of Cape 

 Wrath ; and it is interesting to note that there, as elsewhere 

 in Sutherlandshire, the component pebbles of the conglo- 

 merate are not derived from the underlying gneiss. A large 

 percentage of the stones is made up of rocks of sedimentary 

 origin, such as greywacke, quartzite, hardened shales, and 

 cherty limestones, while a few consist of a slaggy diabase 



