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metamorphic strata to which the same term gneiss had been also un- 
fortunately applied. But no two rocks can be more different than 
those overlying rocks from the fundamental gneiss. I have never 
seen in any part of the South-west Highlands, among the moun- 
tains which McCulloch assigns to gneiss, any rock approaching in 
character to the gneiss of the Hebrides and of the north. The 
question, however, will, I have every reason to believe, be finally settled 
by the proofs which are about to be brought before the Geological 
Society. SirB. Murchison has found that the islands of Islay and J ura 
present perfect repetitions of the phenomena of Sutherland, and that 
the quartz rocks and limestones of Silurian age are superposed 
conformably and without a break by the micaceous and chloritic 
series which occupies such large tracts on the opposite mainland, 
and which, folding over a little south of Loch Tay, and clasping 
round Schiehallion, again rises up to the north of Loch Bannoch, 
and allows the lower quartzites and limestones to reappear. Very 
curious questions arise as to the causes of the metamorphic action 
which has so completely altered the structure of beds lying over 
others which remain comparatively unaffected. Some geologists 
have been inclined to deny the existence of true stratification in the 
micaceous chloritic schists of the South-west Highlands, and to 
assign the appearances to lamination or slaty cleavage. I must say 
I agree entirely in the view taken by Sir B. Murchison, that this 
doctrine is wholly untenable. Indeed, I can with difficulty sup- 
pose its being held by any one who is familiar with the districts 
in which these rocks prevail. It may safely be affirmed that there 
is no one indication or feature of true aqueous stratification which 
is awanting, except the presence of organic remains. There are the 
same alternations of siliceous, muddy, and calcareous beds, which 
everywhere characterise a long continuance of marine deposit thrown 
down under various mineral conditions. 
It is well to observe that this new classification of the rocks in 
the north-west of Scotland adds additional force to an argument long 
ago used by Sir Boderick Murchison in reference to the bearing of 
geological evidence on the great question of the beginning and suc- 
cession of life. The Silurian strata, in which fossils have been 
discovered, are more crystalline and more highly metamorphic than 
the Cambrian strata which lie below them. Yet, in Scotland at 
least, no organic remains whatever have as yet been discovered 
