222 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [Nov. 16, 



after laborious walks, by Professor Kamsay on the Duke of Suther- 

 land's map, which I submit to the inspection of the Society ; but I 

 would here observe that no attempt can be made to insert all these 

 faults with accuracy until accurate Ordnance Survey Maps of the 

 region shall have been completed. 



As bearing on the resemblance of these quartzose and calcareous 

 rocks to their equivalents in America, I may mention that a recent 

 comparison of several of the American so-called fucoids has enabled 

 Mr. Salter satisfactorily to refer them in many cases to the vertical 

 tubes, or, rather, filled-up burrows of large marine worms. He par- 

 ticularly cites the Phytopsis tubulosus of the " Calciferous Sand-rock" 

 of the American geologists ; the celebrated " Birds' Eyes " {Phytopsis 

 eellulosus) of the " Birds'-eye Limestone," and the Buthotrepkis 

 succulens of the Trenton group, as being of this nature. The part 

 played by A nu elides in the older palaeozoic epoch -was, we thus know, 

 very conspicuous. 



Let us now pass to the other parts of the section, fig. 3, which shows 

 the principal or lower limestone resting upon the lower quartz - 

 rock, and succeeded by the vast overlying masses of upper quartz- 

 rock, constituting the lofty range of Ben More in Assynt, the summit 

 of which rises to 3235 feet above the sea. 



Section of Ben More of Assynt. — Viewed on the great scale, 

 as just described, the limestone which lies to the west of the 

 church and village of Assynt occupies a thickness of about 700 or 

 800 feet, whence it spreads out to the east and south over the 

 extensive upland plateau above Stromchrubie, where, however, many 

 quartzose strata prevail in it. As soon as the explorer has passed 

 the small inland lake (Maoloch-corry), well known to sportsmen by 

 containing the " Gillaroo trout," this limestone, so thick and broadly 

 expanded on Loch Assynt, has already diminished to a thin band, of 

 less pure character, which, as you climb to the Bealloeh, or pass 

 under Ben More, is seen to dip beneath the stupendous mass of 

 upper quartz-rock which constitutes the Coniveall, or culminating 

 point of the range. Nowhere is the contrast between the lower and 

 upper quartz-rock more strongly marked ; for, whilst the former is 

 well exposed as a grey rock (c 1 , fig. 2), which weathers white, on the 

 northern flanks of Canisp, where it descends from that mountain to 

 dip under the limestone of Stromchrubie, the upper quartz is pre- 

 sented in the form of a lofty escarpment, the beds of which in their 

 outcrop distinctly overlie the limestone. Here again the pinkish or 

 roseate colour of the overlying mass is strikingly contrasted with the 

 lower quartz, immense quantities of the higher rock having fallen 

 clown upon the edge of the calcareous zone. Whilst I ascended to this 

 pass, where the order is so clearly recognized, Prof. Ramsay com- 

 pleted the proofs by climbing to the summit of the chain, all of 

 which he still found, at a height of 3235 feet, to be composed of 

 quartz-rock, in parts pebbly*. "Wrapping round the sinuosities of 

 the older rocks, these great masses of upper quartz-rock, whether 



* These upper pebbly beds are locally called " Button-stones." 



