1858.] MUECHTSON NOETHEEN HIGHLANDS, ETC. 363 



reproducing this woodcut from ' Siluria ' I willingly transcribe the 

 words of that lamented author : — 



" Rising over a basement of rugged gneiss hills that present the appearance of 

 a dark tumbling sea [the dark lower rocks of the preceding sketch], we descry 

 a line of stupendous pyramids from 2000 to 3000 feet in height, which, 

 though several miles distant in the background, dwarf by their great size 

 the nearer eminences into the mere protuberances of an uneven plain. Their 

 mural character has the effect of adding to their apparent magnitude. Almost 

 devoid of vegetation, we see them bared by the line of the nearly horizontal 

 strata, as edifices of man's erection are bared by their courses of dressed stone ; 

 and, whilst some of their number, such as the peaked hill of Suilven, rise at an 

 angle at least as steep and nearly as regular as that of an Egyptian pyramid, in 

 height and bulk they many times surpass the highest Egyptian pyramid. Their 

 colours, too, lend to the illusion. Of a deep red hue, which in the light of the 

 setting sun brightens into a glowing piirple, they contrast as strongly with the 

 cold grey stone of the gneiss tract beneath, as a warm-coloured buildmg contrasts 

 with the earth-tinted street or roadway over which it rises *." 



The occurrence of powerful red conglomerates on the south- 

 western parts of the coast of Scotland, as shown by Mr. Carrick 

 Moore and myself to be intercalated in the Lower Silurian rocks f, 

 has indeed already prepared us for this identification of these still 

 older Cambrian conglomerates as rising out to the north-west of the 

 same country, where, resting upon the oldest known gneiss of the 

 British Islands, their eroded surfaces are iiTegularly overlapped by 

 quartz-rocks and limestones which are proved by their fossils to be 

 of Lower Silurian age. 



The local distribution of these Cambrian conglomerates and sand- 

 stones of the North-western Highlands, whose maximum thickness 

 as exposed to day is not less than from 2000 to 2500 feet, is demon- 

 strated by the fact, that, in proceeding a few miles only to the east, 

 or into the interior, the fundamental gneiss is either laid bare or is 

 seen to be at once covered by the powerful quartz-rock and limestone 

 series, to the exclusion of those Cambrian rocks which range from 

 various western headlands of Eoss-shire to the bold promontory of 

 Cape Wrath in Sutherland J. 



At Cape Wrath, which I had not visited since the year 1827 

 (when the lighthouse was building), I observed, on its western slope 

 and summit, that the rocks of old gneiss were covered by beds of 

 finely rounded pebbles, which disintegrate into very fine gravel. 

 These beds of the Cambrian rock dip away very slightly (8°) to the 

 W.N.W., — all the pebbles in this conglomerate varying in size from 

 one inch to i of an inch, and being made up of fragments of the sub- 

 jacent old gneiss. In following the coast-ridges to the east, or the 

 Kyles of Durness, the lowest strata of the rock (h) are seen to gra- 

 duate up into the usual red- and purple-coloured hard sandstones 



* This description was read before the Physical Society of Edinburgh in 1854, 

 in the memoir in which Hugh MiUer propounded the theory respecting the 

 quartz-rocks and limestones, to which allusion is afterwards made. The whole 

 was printed in the ' Witness ' newspaper, and ti'ansmitted by the author to myself 

 with an explanatory letter. 



t Quart. Journ. Geol. Soc. vol. vii. p. 149 ; and vol. xii. p. 359, 



\ See Trans. Geol. Soc. 2nd ser. vol. iii. p. 155. 



