1004 REPORT—1885. 
formations and their relations to one another in the one country are almost the 
exact counterpart of what they are in the other. 
The problems which await solution in Scotland are the same which confront 
our brethren in Scandinavia; their difficulties are our difficulties, their successes 
our successes ; if they share the benefits of our discoveries, we equally partake 
with them in the fruits of their achievements. Important links in the chain of 
geological evidence, absolutely wanting in the one area, may perchance be found 
in the other. Every advance, therefore, which is made in the knowledge of the 
rocks of the one country, must necessarily re-act upon the opinions and theories 
which prevail among geologists in the other. 
At the base, and forming the foundation of this greatly denuded mountain- 
chain, there exist enormous masses of highly foliated, crystalline rocks. These, in 
great part at least, underlie the oldest known, fossiliferous strata, and are therefore 
of pre-Cambrian or Archzan age. In spite of the labours of Kjerulf, Dahll, 
Brégger, Reusch, Tornebéhm, and many others in Scandinavia, and of Macculloch, 
Nicol, and their successors in this country, much still remains to be done in study- 
ing the petrographical characters and the geognostic relations of these widespread 
tormations. 
Some thirty years ago it was suggested by Sir Roderick Murchison that among 
these Archzean rocks there exists a ‘fundamental gneiss,’ a formation which is the 
counterpart and contemporary of the rocks in Canada, to which Sir William 
Logan gave the name of ‘ Laurentian.’ Since that time other similar attempts 
have been made to identify portions of these Archzean rocks in the Highlands and 
Scandinavia with crystalline rock-masses in different parts of the New and Old 
World. 
I confess that, speaking for myself, I am not sanguine as to the success of such 
endeavours. The miserable failures which we have seen to have attended similar 
attempts, in the case even of far less altered rocks, where identifications have been 
based on mineralogical resemblances only (and in connexion with which definite 
palzeontological or stratigraphical evidence has been subsequently obtained) ought 
surely to teach us caution in generalising from such uncertain data. It has been 
argued that, where palzeontological evidence is wholly wanting, and stratigraphical 
relations are doubtful or obscure, then we may be allowed to avail ourselves of 
the only data remaining to us—those derived from mineralogical resemblances. 
But surely, in such cases, it is wiser to admit the insufficiency of the evidence, 
and to say ‘ We do not know!’ rather than to construct for ourselves a ‘fool’s 
paradise,’ with a tree of pseudo-knowledge bearing the Dead-Sea fruit of a barren 
terminology! The impatient student may learn with the blind poet that 
They also serve, who only stand and wait. 
It is thought by some that the application of the microscope to the study of rock- 
masses may reveal peculiarities of structure that will serve as a substitute for 
paleontological evidence concerning the age of a rock when the latter is wanting. 
Greatly as I value the insight afforded to us by the microscope when it is applied 
to the study of the rocks, and highly as I esteem the opinions of some of those 
who hold these views, yet I fail to see that any such connection between the 
minute structure and the geological age of a rock has as yet been established. 
Although the bold generalisation which sought to sweep all the crystalline rocks 
of our central Highlands into the great Silurian net has admittedly broken down, yet 
it by no means follows that the whole of these rock-masses are of Archean age. 
Nicol always held that among the complicated foldings of the Highland rocks many 
portions of the older Paleozoic formations, in a highly altered condition, were 
included. The same view has been persistently maintained by Dr. Hicks, to whose 
researches among the more ancient rock-masses of the British Isles geologists are 
so greatly indebted, and also by Professor Lapworth. 
To the settlement of this very important question we may feel sure the effort 
1 See Quart. Journ. Greol. Soc. vol, xix. (1864), p. 184, and Geology and Scenery 
of the North of Scotland (1866). 
