98 Murchison—Laurentian Rocks. 
data definitely before my associates in 1858, when I termed 
these lowest rocks ‘ Fundamental Gneiss ;’ a name intended to 
mark that which was unquestionably a new base for the whole 
stratigraphical series of our country. So truly was this the 
case, that, in the order of superposition fixed upon by my pre- 
decessor Sir Henry De la Beche, when Director-General of the 
Geological Survey, and since approved by myself, after consul- 
tation with Professor Ramsay and Mr. Jukes, the Cambrian 
rocks, altered and unaltered, were placed at the base of the 
whole sedimentary series, and the letter a, as the beginning of 
the alphabet, was affixed to them. 
The fact of the existence of this older or basement formation 
in the North-west of Scotland was again pointed out by me* in 
the following year in a new edition of ‘ Siluria.’ I also pre- 
pared a geological map of the Highlands,}. in which to the term 
‘Fundamental Gneiss’ was added, ‘or Laurentian of North 
America.’ For when I first ascertained this order I was un- 
aware of the results of the labours of Sir W. Logan; but, 
in the following year, having induced Professor Ramsay to 
accompany me, to make sure of the existence of this striking ~ 
new feature, he not only confirmed the accuracy of my sections 
and descriptions, but assured me that my ‘ Fundamental 
Gneiss’ was unequivocally the Laurentian, he (Prof. Ramsay) 
having recently explored the Canadas in company with Sir W. 
Logan. From that moment, wishing to do all honour to the 
distinguished Director of the Canadian Survey, I used the term 
‘ Laurentian,’ both in the memoirs by Mr. Geikie and myself, 
and in our Geological Map of Scotland. 
I call the attention of geologists to these facts because, 
although Sir W. Logan himself has done ample justice to this 
piece of work, and has spoken of it as the first correlation of the 
Laurentian rocks of Britain with those of America,{ I regret 
to perceive that, in the new edition of the ‘ Elements of Geology’ 
just issued, Sir Charles Lyell thus dismisses the subject of the 
Laurentian rocks of Britain:—‘ The oldest stratified rock in 
Scotland is that called by Sir R. Murchison “ the Fundamental 
Gneiss,” which forms the whole of the island of Lewis in the 
Hebrides. On this gneiss, in parts of the Western Highlands, 
the Lower Cambrian and various metamorphic rocks rest un- 
conformably. It is conjectured that this ancient gneiss of 
* Quart. Journ. Geol. Soe, vol. xv. p. 353. 
tT Ibid., plate 12. 
{ See Sir W. Logan’s remarks on this point in the Jast number of the Quart. 
Journ, Geol. Soc., vol. xxi. p. 46. 
