454 
NATURE 
[ Sept. 10, 1885 
but that in other places they appear to be overlain conformably 
by, and even to alternate with, crystalline schists and gneisses. 
He was further able to state that the quartzites of his ‘‘ Primary 
Red Sandstone Formation” contain organic remains, some of 
which he correctly identified as the burrows of marine worms, 
while others he recognised as Orthoceratites (‘‘ Western Isles of 
Scotland” (1819), vol. ii. pp. 512, 543). It is almost painful to 
have to add that his want of appreciation of the value of 
palzontological evidence, a weakness which Macculloch shared 
with so many of the early Scottish geologists, prevented any 
attempt on his part at the correlation of this ‘‘ Primary Red 
Sandstone” with the rocks of other districts ; and thus for more 
than forty years this important discovery remained almost entirely 
fruitless. 
The next step in the history of our knowledge of these High- 
land strata which we have to record, was unfortunately a 
retrograde one. Sedgwick and Murchison, who visited the 
district in 1827, maintained that Macculloch had fallen into 
grievous error, and that his ‘‘ Primary Red Sandstone Formation ”’ 
was in fact no other than an outlying part of the Old Red 
Sandstone (Z7ans. Geol. Soc. ser. 2, vol. iii. p. 155). 
This view was strongly protested against by Hay Cunningham, 
who, writing in 1839, after a careful survey of Sutherland, 
demonstrated the justice of Macculloch’s conclusions, and even 
went beyond that geologist in showing the very intimate connec- 
tion between the quartzite and limestone. He clearly illustrated 
by numerous sections the unconformity of the ‘‘ Primary Red 
Sandstone Formation,” consisting of red sandstone, quartzite, 
and limestone, upon the gneissose rocks, and the apparently 
conformable superposition to it of other schists and gneisses 
(“On the Geognosy of Sutherlandshire,” by R. J. H. Cunning- 
ham, M.W.S. ; Zransactions of the Highland and Agricultural 
Society of Scotland, vol. xiii. (1839). 
Such was the state of geological opinion when, in the winter 
of 1854, the attention of geologists was recalled to this ancient 
formation of Macculloch by the discovery in it of fossils by one 
who fully recognised their value and importance—Mr. Charles 
Peach. These fossils, though imperfect, were sufficient to prove 
that the strata containing them must be of Pa/eozorc age. 
Three of the leaders of geological science at that day appear 
to have been deeply impressed with the importance of this dis- 
covery of Mr. Peach’s; but for a time, at least, the fruits of 
that discovery were missed, through the unfortunate retrograde 
teachings of Sedgwick and Murchison in 1827. 
Hugh Miller, whose splendid researches in the Old Red 
Sandstone had made him ready to welcome any extension of its 
boundaries, suggested that the fossils of Durness might belong 
to the marine Devonian. 
Roderick Murchison, who in his younger days had worthily 
conquered a kingdom in Siluria, and by successive annexations 
in his later years had sought to convert this kingdom into an 
empire—one which should embrace all the Lower Paleozoic 
rocks of the globe—was not unwilling to claim his native High- 
lands as part of this ever-growing realm. 
James Nicol, who had been the first to discover graptolites in 
the rocks of the Scottish Borderland, and had thus demonstrated 
their Silurian age, was so struck by the resemblance of some of 
the slaty rocks of the Highlands to the fossiliferous shales of his 
native district, that, ten years before Peach made his important 
discovery, he had suggested the probability of the Highland 
schists and gneisses being simply the Borderland shales and 
greywackes in an altered state (‘* Guide to the Geology of Scot- 
land” [1844]). Hence Nicol, equally with Murchison, was 
prepared to accept the Silurian age of the Durness limestone, 
and of the rocks associated with it. 
Murchison, still full of his old enthusiasm for discovery, 
determined to love no time in putting to the test the truth of the 
suggestion made by his old friend Nicol and himself; and 
accordingly, shortly before the meeting of the British Association, 
which was fixed to take place in the year 1855 at Glasgow, we 
find the two friends making their way into the wild district of 
North-west Sutherland. 
Unfortunately the time was too short and the weather too 
unpropitious for the task they had set before themselves. 
When this Geological Section assembled at Glasgow, 
Murchison declared his conviction that the limestone of Dur- 
ness, which had yielded the fossils to Mr. Peach, was of Silurian 
—that is, as he employed the term—of Lower Paleozoic age. 
But he, at the same time, maintained the truth of his old views, 
that the red sandstones of Applecross and Gareloch are in 
reality nothing but Old Red Sandstone (‘‘ Brit. Ass. Rep.” 
1855); Zvans. of Sec. p. 87), and in this latter contention he 
received the warm support of Sedgwick, who was also present 
at the meeting (Geikie’s ‘‘ Memoir of Sir Roderick Murchison” 
(1875), vol. ii. p. 207). 
Nicol, on the other hand, appears to have been greatly 
dissatisfied with the results of this hasty and inauspicious journey 
to Sutherland. While, however, withholding his judgment as 
to the age of the several rock-masses, he insisted, in opposition 
to the views of Murchison and Sedgwick, that the whole of the 
vast series of Red Sandstones in Applecross and Torridon is, as 
Macculloch showed, inferior to the quartzite and limestone 
(see Nicol’s ‘*Geology of the North of Scotland” (1866), 
Appendix, p. 96). 
In the summer of the next year, 1856, Nicol, so soon as he 
was released from his teaching work in this university, hastened 
back to the Western Highlands to try and resolve some of the 
doubts which troubled him concerning the age and succession of 
the strata. This summer’s labour was productive of great and 
important discoveries. In the first place, he was able to com- 
pletely confirm the conclusions of Macculloch and Hay Cunning- 
ham, that a// the Red Sandstone of the Western Islands, with 
the exception of some small patches of ‘‘ New Red,” belong to 
an old formation underlying the quartzite and limestone. But 
his researches also enabled him to show that Macculloch’s 
‘* Primary Red Sandstone” in reality consists of ¢wo formations, 
the lower—to which he subsequently gave the name of the 
“*Torridon Sandstone”—lying unconformably on the gneiss, 
and the upper (consisting of quarzite and limestone, containing 
fossils) resting everywhere unconformably upon, and overlapping, 
the sandstones. It is avery noteworthy circumstance that while 
Nicol admitted the accuracy of the descriptions of Macculloch 
and Hay Cunningham which seemed to point to a conformable 
superposition of beds of gneiss to the quartzite and limestone, 
the results of this first summer’s work had already raised serious 
misgivings in his mind as to the correctness of this conclusion, 
for he wrote as follows :—‘‘ The fact of the overlying gneiss 
having been metamorphosed 7 sz¢z, and not pushed up over the 
quartzite, is one requiring further investigation” (Quart. Fourn. 
Geol. Soc. vol. xiii., 1857, p. 35). It is not surprising, how- 
ever, to find that Nicol was so staggered by the magnitude of 
the faults which would be required to bring about such a result, 
that for more than a year he hesitated to accept this, which we 
now know to be the true, explanation of the phenomena. 
There was a suggestion—and it was nothing more than a sug- 
gestion—made by Nicol at this time, which has often been very 
unfairly quoted to his disadvantage. Convinced that Macculloch 
was right as to the infraposition of the Torridon Sandstone to 
the quartzite and limestone, and strongly inclined to accept 
Murchison’s confident assertion that this Torridon Sandstone was 
simply the ‘f Old Red,” Nicol pointed out that the only possible 
way of harmonising these two views was to suppose that the 
quartzites and limestones were of Carboniferous age; and he 
showed that the imperfect fossils which had been up to that time 
obtained at Durness were not sufficient to negative such a sup- 
position (Quart. Four, Geol. Soc. vol. xiii., 1857, p. 36). 
But during the summers of 1857 and 1858, Nicol continued 
his labours in the Western Highlands, with the result of clearing 
away many of his difficulties and perplexities. Murchison, too, 
had revisited the district, and seen that his idea of the ‘* Old- 
Red” age of the Torridon Sandstone would have to be finally 
abandoned, and that Macculloch’s views, as amended by Nicol, 
concerning the relations of the Highland rock-masses must be 
accepted. Salter, too, examining more perfect specimens of 
fossils which had in the meanwhile been obtained from the 
Durness limestone by the indefatigable Mr. Charles Peach, 
showed that they were certainly of dower Paleozoic age (Silurian 
of Murchison). 
The position taken up by Murchison, and on which he made 
his final stand, was simply arrived at by combining the strati- 
graphical conclusions of Macculloch and Nicol with the palz- 
ontological results of Peach and Salter. 
Murchison attended the meetings of this Association at Dublin 
in 1857, and at Leeds in 1858, on both occasions making use of 
the opportunity for explaining in detail his ideas concerning the 
age and succession of the Highland rocks. On the latter 
1 Colonel Sir Henry James is said to have made similar observations 
during the same season, the summer of 1856, and to have communicated 
them to Sir Roderick Murchison by letter. But there can be no doubt that 
eee ee was made quite independently, and he was the first to 
publish it. 
