432 
SCOTPS LAST EXPEDITION 
is no method of ascertaining what thickness of strata 
has since been denuded from the surface. The folding 
and heating of the rocks has since quite destroyed all 
evidence of the animal or vegetable life of that time, 
though numbers of small graphite particles, found in 
the crystalline limestones, may be the remnants of 
carbonaceous growth in the ancient coral reef. 
Our earliest view, therefore, of the region is that of 
a sea bordered by land long since used up in forming 
these deposits of mud, sand, and limestone. The gneisses 
were in some cases huge intrusions of granite connected 
with the up-and-down movements referred to, and in 
other cases conglomerates, formed close to the coast- 
line by waves or rivers. It is probable that there was 
life of the lower forms in these seas, their skeletons being 
now altered beyond all recognition. 
Between the deposition of the crystalline schists 
and the next succeeding strata there is a vast gap, yet 
the mere existence of a gap in the geological record 
means something, and we may interpret it as marking 
a period of uplift in that area, so that it was dry land, 
and instead of receiving further deposits, became the 
source of deposits laid down in neighbouring seas. In 
the vast period of time that this gap represents, most 
of the alteration and folding of these rocks took place, 
for the later strata are comparatively undisturbed. The 
mechanics of these huge earth-movements are hidden 
from us, but they partook of the character of a shrinkage, 
and the strata were folded and plicated into only a 
fraction of their former horizontal extent. Further, the 
