P. MACNAIR ON ROCKS OF HIGHLAND PERTHSHIRE. I 67 
subsequently published in the Quarterly Journal of the Geological 
Society of London. We all know how the far-reaching con¬ 
clusions which it involved were set aside by the great weight of such 
names as Murchison, Harkness, Ramsay, and Geikie, who opposed it in 
favour of a certain hypothetical succession, and how in this oppo¬ 
sition Scottish Geology received a blow from which it was destined not 
to recover for a space of nearly twenty years. Professor Lapworth 
reawakened an interest in the study of the Highland problem, with 
the result we have just mentioned. This was followed by the detailed 
mapping by the officers of the Geological Survey, the consequence 
of the whole being that a new impetus was given to the study of the 
Highland rocks, which has continued since that time. It must be 
confessed, however, that little advance has been made upon the general 
principles laid down by Nicol both for the north-west and southern 
Highlands, although the unravelling of the minute details of these 
regions has tended in a remarkable way to confirm the broader gene¬ 
ralisations of that famous stratigrapher, and has brought us face to 
face once more with many interesting problems in the structure, 
succession, and metamorphism of these Highland rocks, which for 
so long a period had been entirely neglected. 
In the first part of this paper we propose to glance at those 
memoirs which were published by Murchison and Geikie, Harkness, 
Jamieson and Nicol, on the geological structure of the southern 
Grampians, about the years 1860-63, and to show that Nicol had 
already grasped the main features of the geological structure of that 
region, and that he maintained his views against the opposition of 
all the leading geologists of the day. We shall then proceed to a 
review of some of the more recent investigations into these rocks, 
which will bring us up to the present time and show us the remark¬ 
able confirmation which NicoFs work has received, alike for the 
southern Highlands as for the north-west. We also propose to discuss 
shortly the more recent advances which have been made in the study 
of those altered igneous rocks which, during the plication and folding 
of the Highland rocks, have become deformed into epidorites and 
hornblende schists. It will be remembered that the first important 
contribution to the elucidation of the origin of these rocks was made 
in 1885 by Mr. J. J. Harris Teall in his valuable paper “On the 
Metamorphosis of Dolerite into Hornblende Schist as displayed in a 
Dyke near Scourie in Sutherlandshire,” and we propose to see how 
far these principles may be applied to the altered basic igneous rocks 
of Highland Perthshire. Lastly, we intend to give an account of the 
more recent researches which have been made into those igneous 
complexes distributed here and there through the southern Grampians, 
and the peculiar metamorphic phenomena seen in the neighbourhood 
