TRANSACTIONS OF SECTION C. 1025 
is certainly a member of the group of Dicynodontia. Geologists will not underrate 
the value of this discovery in its bearing on the question of the age of the reptili- 
ferous sandstone of Elgin, 
3. Report on the Fossil Plants of the Tertiary and Secondary Beds of the 
United Kingdom.—See Reports, p. 396. 
MONDAY, SEPTEMBER 14. 
The following Papers were read :— 
‘lL. The Highland Controversy in British Geology: its Causes, Course, and 
Consequences. By Professor Cartes Lapwortu, LL.D., F.G.S. 
Part I. 
The author gave a réswmé of the views of the earlier geologists respecting the 
geological age and possible mode of formation of the Highland Metamorphic rocks, 
and sketched in brief the rise and progress of the controversy between Sir R. 
Murchison and his followers on the one hand, and Professor Nicol of Aberdeen on 
the other, till its temporary close in 1855 by the publication of the Highland 
Memoir of Murchison and Geikie. He then reviewed the re-opening of the 
controversy by Dr. Hicks in 1877, and the work of the Archzan geologists, up to 
the date of publication of Dr. C. Callaway’s paper in 1883, in which Nicol’s view 
of the great physical break between the Paleozoic rocks and the Eastern or Upper 
Gneissic series was shown to be correct ; but the so-called Eastern Gneiss was pro- 
visionally erected into a new Archwan system, having the Arnaboll Gneiss as its 
lower member. 
The author next gave a summary of his own views, as deduced from his personal 
study of the Durness-Eriboll district in 1882 and 1883, illustrating them by 
coloured maps and sections. He held that (exception being made of the local 
Torridon sandstone) the only rock-formations in the Durness-Eriboll area are, as 
Nicol originally contended,—(1) the Archwan or Hebridean gneiss,and (2) the 
Palzozoic quartzites, fucoid beds, and limestones. 
There isno conformable ascending succession from the Palzozoie rocks into the 
Eastern Metamorphic series. The line of contact is, generally speaking, a plane of 
dislocation, and where this is wanting the Paleozoic rocks rest unconformably upon 
one of the members of the Eastern Gneiss. The present physical relations of the 
Eastern Metamorphic series are the effect of lateral crust-creep, by which the 
Eastern Metamorphic rocks have been forced over the Paleozoic rocks to the west, 
often for many miles. This Eastern Metamorphic series is composed of two 
petrological members, the Arnaboll gneiss to the west, and the Sutherland schists 
and gneiss to the east, having between them a series of variegated schists possess- 
ing characters common to both. The Arnaboll gneiss is simply the easterly 
extension of the Hebridean of the west. The remaining gneisses and schists of the 
Eastern Metamorphic series are mainly composed of remetamorphosed Hebridean, “ 
with included patches of igneous and Paleozoic material. The planes of schistosity 
which divide the layers of the Upper Gneissic series are not planes of bedding, but 
planes of dislocation. The present dip, strike, and mineralogical characteristics 
of these rocks haye been given to them since Silurian times, by the agency of the 
great earth movements. In some instances the original structures of the rocks are 
still recognisable ; frequently, however, they are more or less obliterated, the old 
minerals have disappeared as such, and new minerals have been developed. The 
Eastern Gneissic series of this area has thus no pretension whatever to the title of 
a sedimentary rock-system. It isa petrological rock-massif, a metamorphic com- 
pound, composed of local elements of different geological ages, In all their essentials 
1885. 30 
