468 Bibliographical Notice. 
structure and geographical features of his native country ; secondly, 
to claim his share of credit for early and long-continued labour in 
working out the geology of Scotland; and thirdly, once more to 
protest against the now very generally accepted interpretation of the 
complicated phenomena of granites, schists, limestones, quartzites, 
and other altered rocks in the north-west Highlands, as elaborated 
by Murchison and Geikie, Harkness, Ramsay, and others. We 
must leave the disputed point, as to whether there be one (Nicol) or 
two sets of gneissose rocks in the Highlands, to the personal observa- 
tion of working geologists, who for years to come will have to tramp 
over moss and moor many a weary day before all the details of strati- 
fication are conned and noted, and before what belongs to Lower and 
what to Upper Silurian is rightly determined in those wild regions. 
Nor can we be historians of the progress of geological knowledge in 
Scotland. The part that Prof. Nicol has so worthily performed can 
be readily known by reference to the publications quoted (and almost 
the only ones quoted) in the little book before us. We can, how- 
ever, assure our readers that we have had real pleasure in reading 
some very eloquent passages in Prof. Nicol’s Lectures, which are 
clear, earnest, and conscientiously true to the author’s hard-won ex- 
perience. Excepting that so many equally well informed geologists 
interpret the natural sections of the strata otherwise than he does, 
his view, of the great gneissic area being fissured from N.H. to S.W., 
with an alteration of level, might well command belief as being quite 
in accordance with the general structure of the region, where the 
edges of the strata run S.W.-N.E., partly from longitudinal folds, 
partly from great faults, holding the same direction and inter- 
sected by transverse fissures, breaking the land into large irregular 
masses. ‘*'These lines of elevation and of fraction have determined 
the lines along which rivers and other denuding agents have acted ; 
and consequently the systems of mountain-chains and river-valleys.” 
The action of ice in this disintegration of the surface is little alluded 
to; but the student can turn to Geikie’s account of the Scottish 
scenery for an enthusiastic treatment of its effects. Our author, 
among his other “‘ conservative” tendencies, ignores the hypothesis 
that refers many lake-basins to ice-action, which, he says, ‘‘ may 
somewhat widen or deepen a valley, but not excavate a lake below 
its level. There is, however,’ he adds, ‘‘no mystery in the forma- 
tion of lakes. Like the valleys in which they lie, they have been pro- 
duced in more ways than one. Some have originated in great slips, 
—masses of the strata being thrown down, and the hollow then filled 
with water. Such is Loch Maree, as shown by the sandstone islands 
lying far below the gneiss hills on the shore. Many may have been 
excavated entirely by river-action—frequently, however, along the 
line of faults. The changes in the relative level of the different por- 
tions of the country explains the origin of very many. The western 
division, as the form and character of the coast prove, has subsided, 
gone down into the sea, since the eastern rose. By this change of 
level, valleys formerly dry and drained by rivers may have been con- 
verted into lakes. Their formation, therefore, requires no extraor- 
