120 Notices of Memoirs—Prof. M. Bertrand— 
no other part of Europe has it been possible for geological mapping 
to be carried further, or to do greater honour to its authors. 
I. Before describing the results of the most recent work, it will 
be well to say a few words as to that which preceded it. This part 
of Northern Europe has long been famous for the discussions to 
which it has given rise. The discovery of fossils in the Durness 
limestone in 1854 induced Murchison to study the region, and it 
was he who drew attention to the peculiarities of its structure; a 
thick series of sediments, quartzites and limestones, rests to the 
west on the gneisses of the coast, and dips regularly, and at a 
somewhat low angle, beneath an enormous mass of micaceous schists 
and of other gneisses, without presenting anywhere indications of 
interruption or unconformity. Murchison concluded that the upper 
gneisses were “newer gneisses,” and that these must be regarded as 
Silurian deposits, overlying the fossiliferous beds, and metamorphosed 
at a later period. 
Professor Nicol, of Edinburgh, who accompanied Murchison on 
his first visit, was the first, on returning to the same investigation 
in the following years, to propose a different interpretation. He 
thought that the Silurian quartzites and limestones of the base were 
repeated several times by folds and by faults; that the conformity 
with the upper gneisses was only local and apparent, and that in 
reality there occurred between them a fault along which the 
gneisses of the east had been pushed over the Silurian. These 
remarkable views—destined to brilliant confirmation in the future— 
were supported by a comparison with the known phenomena of the 
Alps. They were unfortunately not accompanied by those decisive 
proofs which would at that time alone have caused such innovations 
to be accepted. Murchison’s authority prevailed, and for more than 
twenty years the existence in Scotland of Silurian gneisses was 
admitted without discussion, and unreservedly. 
The question, taken up from 1878, in the notes of Messrs. Hicks, 
Bonney, Hudleston, and Callaway, entered upon a new phase upon 
the publication of the memorable Memoir by Professor Lapworth, 
entitled “The Secret of the Highlands. Professor Lapworth, in 
1882 and 18838, set himself to make a detailed survey of the Durness 
and Erriboll districts ; he was thus led to revive the views of Nicol, 
but supported this time by decisive proofs. 
These proofs were singularly difficult to discover. Fossils were 
wanting, or nearly so; it was necessary to carry out a stratigraphical 
study based upon lithological characters only, and in order to do 
this it was requisite that a sufficient number of precise horizons 
should be singled out in a series very uniform in appearance, or at 
least in which there were only two very distinct members. I re- 
member the astonishment, I might almost say the terror, which 
seized M. de Margerie and myself the first day, when Mr. Peach 
pointed out to us the characters which differentiated these successive 
horizons ; their apparent insignificance, their almost intangible 
1 Grou. Mae. Decade IT. Vol. X. 1883, pp. 120, 133, and 137; and Proc. Geol. 
Assoc. 1884, vol. viii. p. 438. 
