Murchison—Laurentian Rocks. 99 
Scotland may correspond in date with part of the great Lauren- 
tian group of North America.’* 
Now I think that the labours which, according to the subse- 
quent surveys of Ramsay, Harkness, He ames, and Geikie, as well 
as the opinion of Sir W. Logan, ‘established for the first time’ 
a Laurentian equivalent in the British Isles, or, in other words, 
a new base for all our series of deposits, were something more 
than a conjecture. A Laurentian base became an established 
fact, and, as such, has been laid down on our geological maps. 
Hence all young geologists, who take their belief from these 
‘ Elements,’ ought, i submit, to have been made acquainted 
with it. For, although previous geologists had treated of this 
gneiss, they had not shown that “it was entirely distinct from 
all the superjacent and younger gneiss, now shown to be of 
Cambrian and Silurian age, nor had they indicated the re- 
markable fact of the entirely divergent direction of its strata. 
I can only account for Sir Charles Lyell’s having regarded the 
establishment of the existence of Laurentian rocks in Britain as a 
‘conjecture,’ by supposing, that of late he has been so absorbed 
in the production of his last remarkable work ‘The Antiquity 
of Man,’ that he has failed in paying sufficient attention to the 
progress of discovery in our islands at the other end, or beginning, 
of the geological scale. In his Address to the British Associa- 
tion at Bath, he naturally revelled with delight on the discovery 
of the Lozoon Canadense in the Lower Laurentian rock. Let 
me say that I rejoiced with him; for there was nothing in the 
finding of one of the lowest orders of animals in the lowest known 
sedimentary rock which in any degree interfered with my views 
of a succession from lower to higher animals, in succeeding 
deposits, as founded on all our existing knowledge. On the 
contrary, this discovery seemed to me to confirm that view; and 
Sir Charles rightly declared, that thereby the word ‘ Azoic’ 
must be dismissed from our nomenclature. At the same time 
all old geologists knew that we who used the term ‘ Azoic’ did 
so solely because at the period of its use no signs of life had 
then been found in these lowest rocks. 
And here I also rejoice to find, by reference to the last 
number of the GEoLoGICcAL MAGAZINE, that one of these low 
organisms, identical indeed with the Eozoon of Canada, has 
been found, by Mr. W. A. Sanford, in the green serpentinous 
limestone of the crystalline rocks of the Bins of Connemara, 
in the North-west of Ireland. ‘This fact, affirmed as it is by 
separate experiments of Professor Rupert Jones, is of exceeding 
* Elements of Geology, 6th edit. p. 580. 
H 2 
