ihe J. FE. Marr—Origin of Archean Rocks. 
wide-spread denudation no longer occurs with such violence, but 
great denudation for long periods still goes on in mountain chains, 
and there we should expect to find regionally metamorphosed rocks 
of later age. 
One or two objections to the view of the volcanic origin of the 
Archean rocks may be here discussed. Of course, any convincing 
proofs of the marine origin of beds of this age would be fatal to their 
terrestrial and voleanic origin in the manner above suggested. At 
the same time, it may be pointed out that local aqueous deposits 
might be formed in lakes upon the land, or that moyas poured out 
from craters would form layers of argillaceous sediment, which 
would resemble marine deposits. Such an argillaceous band has 
been mentioned by Prof. Bonney as occurring amongst the quartz 
felsites at the foot of Llanberis lake, but it is very thin. 
A very great difficulty is that connected with the evolution of 
life. A large part of the earth would be absolutely unfitted for 
life when the volcanic rocks were being accumulated, consequently 
the rich variety of forms in the Harlech rocks of St. Davids is very 
perplexing. It may be remarked, however, that according to the views 
above advanced, great deposits of sediment would be formed in the 
ocean basins long before the present continental areas had become 
submerged, and there would be a violent struggle for existence 
in these oceans, owing to the abnormal rate of physical change ; 
these rocks, if thus formed, are for ever lost to us, and we can 
never hope to find traces of the earliest organisms, buried beneath 
our present oceans. It by no means follows that we need despair 
of finding organisms older than those of the Harlech rocks of St. 
Davids. It has been pointed out with what great irregularity the 
earliest Cambrian sediments were deposited, so that somewhere or 
other in our present Continental areas, rocks of Cambrian age, and 
earlier than the Harlech beds of St. Davids, may be discovered. 
The great thickness of rocks in North Wales and the Longmynd 
Hills, as compared with those of St. Davids, is doubtless partly due 
to their shallow-water character, but perhaps also to the lowest 
rocks in these areas having been formed before the St. Davids area 
was submerged, and where such rocks have not had their organisms 
obliterated by subsequent cleavage, we may hope to find less 
differentiated forms than those of the Caerfai rocks of St. Davids. 
Again, there are many other difficulties besides the one here raised, 
against the acceptance in full of the theory of natural selection, 
which have been noted by various paleontologists, among whom 
may be mentioned Barrande, Carruthers, and, Blake; and I find the 
following remark in a lecture recently delivered by a biologist and 
paleontologist (Prof. L. C. Miall, “The Life and Work of Charles 
Darwin,” Leeds, 1883, p. 81) :—‘The Darwinian has to make much 
of the imperfections of the geological record, in order to avoid the 
inference that the divergence of animal forms has seldom extended 
to classes; seldom, indeed, to orders. J am willing to concede all 
that is asked on this head; but I cannot as yet find in Paleontology 
the proof, and, indeed, hardly the possiblity, that all animal life has 
had a common origin.” 
