1888-89.] The Duke of Argyll on Bodies of Organic Origin. 49 
consequently mistook the real meaning of certain confused sections 
in the middle zone of that disturbance. But, after all, the horizon 
of the Archaean gneiss on the west coast, with that of the Cambrian 
sandstones overlying it, and the other horizon of the Old Red on 
the east coast, with the Oolites and Lias on the top of it, remain 
fixed points in the interpretation of the whole section ; whilst the 
discovery of a copious fossil fauna exactly where Macculloch sus- 
pected it would be found, leave no doubt of the Lower Silurian age 
of the great mass of strata overlying the Cambrian sandstones and 
the white quartzite on the west, and presumably underlying the 
Old Red upon the east. 
The result of this conviction as to the substantial truth of Murchi- 
son’s generalisation, has led me to anticipate with some hopeful 
expectation the discovery of organic remains, some day, among the 
metamorphic rocks of Argyllshire as belonging to the Lower Silurian 
series. With this view, I have often carefully examined the cal- 
careous beds which are abundant there, but always hitherto without 
result. Impressed, however, with the specially fossiliferous character, 
as regards annelids at least, of the sandstone or quartzite deposits in 
the north, I determined on my return home, in September last, to 
examine carefully a few beds of that rock which I had long known 
to occur close to my own residence at Inveraray. Those beds form 
no noticeable feature in the country. They make no show upon the 
hills, nor are they conspicuous on the shores. Crystalline quartz is 
indeed abundant — in veins and in masses. Thin beds or bands 
among the mica-slates, which are more or less silicious, are also 
abundant. But true quartzite, well stratified and bedded, is very rare, 
so rare that I know of it as occurring only at two spots on the shores 
of Upper Loch Tyne. Close to the town of Inveraray there is a 
little headland or promontory, called Craig-na-clmrach, which 
exhibits a series of true quartzite beds, that may be from 30 to 40 
feet thick. It has been a good deal quarried and used for making 
breast walls against the sea. I had also frequently examined it 
for metallic ore, since galena is present in detached spots through- 
out some of the beds. I had also observed some strange cavities 
in it filled with sand or clay coloured with iron oxide. But 
nothing had ever suggested itself to me as indicating organic 
remains. I knew, however, that the same quartzite, although in very 
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