124 Prof. C. Lapworth—The Secret of the Highlands. 
the base, overlain unconformably by (6) a second metamorphic series ; 
composed, in ascending order, of the quartzite, the gneisses of Sango 
Bay, etc., etc., and the flaggy schists of Fair Head, Loch Hope, and 
Central Sutherland. He infers that the Paleozoic Durness Limestone 
was deposited upon the contorted gneiss, and owes its apparent infra- 
position to the latter merely to the effects of faults.’ 
I]J.—Results in the Durness Area. 
In my study of the Durness area I ascertained that the following 
facts, among many others, are easily made out upon a careful mappin 
of the ground. 
1. The Lower Quartzite rests at a gentle angle unconformably 
upon the almost vertical edges of the Lewisian or Hornblendic gneiss. 
2. The highest bed of the Quartzite is a flaggy zone pierced by 
innumerable vertical annelide tubes. (Pipe-rock of Nicol.) 
3. The Durness Limestone, though at first sight apparently homo- 
geneous, of great thickness and of very gentle inclination, is actually 
made up of a few distinct lithological zones, repeated again and 
again in a series of faults or inverted folds. It is hardened and 
more or less crystalline throughout, but contains abundant relics of 
Maelurea, etc., upon one special horizon. 
4. The Limestone is visibly overlain in excellent readable sections 
and at a very low angle by a series of wrinkled shales, micaceous 
flagstones and slaty schists, with intercalated zones of hornblendic 
eneissose schists; and even where transversely faulted against the 
limestone, this overlying series agrees precisely with the underlying 
limestone zones in dip, strike, and apparent amount of convolution. 
As this physically overlying series is the Upper Flaggy gneiss 
series of Murchison, it would appear, at first sight, that his theory 
of the sequence, so far asthe Durness area is concerned, is absolutely 
impregnable. 
Such, at least, would be the unhesitating conclusion of any geolo- 
gist whose field experience had been confined to the study of the 
gently inclined and slightly folded rocks of the Newer Paleozoic 
and more recent formations of Britain. But to those who, like my- 
self, have been led again and again into error and difficulty by a too 
hasty reliance on apparent sequence among the excessively convoluted 
Lower Paleozoic rocks, it is needless to point out how utterly worth- 
less is such evidence as this, in highly plicated and inverted strata, 
unless it be confirmed by other and more convincing testimony. 
And the folding, wrinkling, and inversion in the Durness area is 
excessive. The laminz on almost every slab from the schistose and 
gneissose rocks exhibit the most extraordinary wrinkling and pucker- 
ing; while the geographical distribution of the petrological zones of 
the Durness Limestone can only be satisfactorily interpreted upon 
the hypothesis that they are arranged in a number of flattened 
arches and troughs, whose very oblique axes all dip in one and the 
same general direction. Before discussing, however, the most natural 
methods of developing the true sequence of the beds in a complicated 
1 Quart. Journ. Geol. Soc., May, 1881. 
