1888 - 89 .] The Duke of Argyll on Bodies of Organic Origin. 41 
absolutely azoic ; and from the intense mineralisation of its substance 
it is not very probable that it will ever afford ns any glimpse 
into the great secrets connected with the origin of life upon our 
planet. 
The enormous mass of red and gritty Cambrian sandstones and 
conglomerates which have been deposited upon the upturned edges 
of the Archaean gneiss, is in a very different mineral condition. I 
found in it myself, very lately, some thinly bedded deposits, on 
which the ripple-mark of the waters in which it was accumulated 
were as well marked and as fresh, apparently, as the ripple-marks 
left upon any of our shores by the tides of yesterday. There seems 
to have been no important alteration in its mineral constituents 
since the time when its sands and gravelly conglomerates were 
thrown down in seas or lakes having a bed of the primeval Archaean 
rocks. Yet through thousands of feet of thickness, until very 
lately, no trace of organic life had been detected ; and even now, 
as the result of the most careful examination by the Geological 
Survey officers in all the beds of this vast deposit, the indications 
of life are not only few, but exceedingly obscure. 
The case, however, is very different when we ascend to the highest 
of this triple group of rocks — when we go to the top of the red 
sandstone mountains, and examine, or even carelessly walk upon the 
white and flaky quartzites which lie upon them. It is impossible 
not to notice the curiously spotted, or pitted surfaces of the white 
slabs, which in many places look like nothing so much as the soles 
of a labourer’s shoe, covered with projecting hob-nails. On 
examination, one finds that these little knobs, or nail-heads, are the 
projecting ends or tops of cylindrical rods which penetrate through 
the whole substance of the rock, so that if we lift one layer, and 
look at the next floor of rock below it in the bedding, we can trace 
the repetition of similar rods down, — down, — down — from the very 
top to the very bottom of the deposit. The extreme roughness 
which they sometimes present upon the surface is thus found to 
be due to the fact that the quartz graining or structure of the rods 
is harder than the graining of the intervening spaces, — so that 
this surface weathers away the fastest, and the tops of the rods 
stand out like the nail-heads in the shoe. But these rods can often 
be detected when there is no such indication on the surface. I 
