14 A. Geikie—Crystalline Rocks of the Scottish Highlands. 
now taught me that I have been mistaken, for the parallelism 
in question is not due to conformable deposition. The same 
kind of evidence of upthrust and metamorphism which these 
coast-sections reveal can be traced southward for a distance of 
more than ninety miles, The task of unraveling the geolog- 
ical structure of these southern regions will be much facilitated 
by the remarkable persistence of the Sutherland Silurian zones, 
some of which, with their characteristic features and fossils, 
are as well marked above Loch Carron as they are at Loch 
Eriboll. 
In southwestern Ross-shire the platform on which the Silu- 
rian rocks rest is a thick mass of Cambrian red sandstone. In 
they present increasing evidence of intense shearing ; fluxion- 
micaceous schist, in which, however, the original clastic grains 
are still recognizable. They finally shade upward into green 
schists and fine gneiss which merge into coarse gneiss with 
pegmatite. The short space within which ordinary red feld- 
spathic sandstone and arkose acquire the characters of true 
schists is a point of some importance in regard to the change 
from the unaltered Silurian strata of the Southern Uplands 
into the metamorphic condition of the Highland phyllites, 
t 
rits, ete. 
Obviously the question of chief importance in connection 
with the structure now ascertained to characterize the North- 
West Highlands relates to metamorphism. That there is no 
longer any evidence of a regular conformable passage from 
fossiliferous Silurian quartzites, shales and limestones upward 
into crystalline schists, which were supposed to be metamor- 
phosed Silurian sediments, must be frankly admitted. But in 
exchange for this abandoned belief, we are presented with 
startling new evidence of regional metamorphism on a colossal 
scale, and are admitted some way into the secret of the pro- 
cesses whereby it has been produced. 
From the remarkably constant relation between the dip of 
the Silurian strata and the inclination of their reversed faults, 
no matter into what various positions the two structures may 
have been thrown, it is tolerably clear that these dislocations. 
