488 
THE GEOLOGIST. 
the quartz-rocks and limestones of Durness and Assynt. Tlic author mentioned 
also that Professor llarkness, having sul)sequently traversed the ground, had 
supplied him with sections and notes confirming the aecuraey of his views, and 
especially illustrative of that phenomenon to wliieh Sir lloderick had attributed 
the greatest importance, namely, the broad distinction between the fundamental 
gneiss and the micaceous seliists and flagstones superposed on the Silurian 
quartz-rocks and limestones. 
llcferring to the gneiss of Cape Wrath as the fundamental rock of the dis- 
trict, and as the equivalent of the " Laurentian rocks" of Canada, Sir Roderick 
pointed out its massiveness, its granite-veins, its high degree of metamorphism, 
and the westerly dip of its laminro, as characters distinguishing it from the 
micaceous flagstone and cldoritie schists which have been termed the "younger 
gneiss," which has agenend easterly dip, and which, wlien near intrusive rocks, 
take on a gneissose structure, especially to the east. A few more details were 
given of tlie red sandstones and conglomerates of Cambrian age lying uncon- 
formably on gneiss. The Silurian quartz-rocks and limestone were then de- 
scribed as seen in their successive and conformable strata in tlu-ee clear and 
important sections, showmg how completely the chief limestones lie between a 
lower and an upper quartz-rock ; and how all this series is foUowed by another 
limestone, which ia its turn is conformably overlaid by micaceous flagstones. 
The flrst of these sections is to be traversed along a line from the post-office of 
Assynt, on the west, across the ridges of limestone of Inelmadamfi' to the 
quartzose hills of Cnocandiien, Ben Uran, and Ben More, to Kinloch and Loch 
Ailsh. Some greenstones are interbedded at Inehnadamff and at Loch Ailsh, 
and some porphyry intrudes at Cnoeandrien, but the conformable sequence of 
the strata is not thereby at all interfered vnth. 
The next section is on the south bank of Loch More. Here the lower 
quartz-rock lies unconformably on the bottom gneiss, the Cambrian rocks being 
absent, and a gradual passage from the upper quartz-rock into the micaceous 
flags of Ben Neath and Kinloch was clearly seen. A third, and, if anything, a 
still bett er section was folio wed from Bcnspionnach, on the west, across Loch 
EriboU to Meolbadvartie and Ben Hope. Above EriboU a specimen of Oriho- 
ceras BrongnUtrtii has been found iii the quartz-rock overlying the lower lime- 
stone. The upper limestone is here overlaid by a clear succession of quartzose 
beds and micaceous flagstones, wlucli pass upwards into mica-seliists of Meol- 
badvartie, in which is niterbedded a thin band of felstone, without any disturbance. 
This condition of the strata extends along the strike for twenty or thirty miles 
at least. At Whiten Head, the northern prolongation of the quartz-rock of 
EriboU, the limestone has died out, and the two quartzose bands have united 
into one great series. The author observed no reversal in the dip of the over- 
lying micaceous beds at any point along the northern coast ; and he was 
strengthened in liis conviction that these flaggy strata, altered here and there 
by plutomc influences, ai-e really an overlying series, younger ui age than the 
lower Silurian quartz-rocks and limestones of Durness and Assynt. Sir 
lloderick further repeated his belief that probably the crystalline rocks of the 
Higlilands will be mainly found to fall into the same category, and wiU in time 
be paralleled with Silurian rocks of the south of Scotland. Lastly, he ob- 
served that, with local exceptions, he bcUeved that these flagstones and mica- 
schists were unaffected by mechanical cleavage. 
Geologists' Association. — The meetings of this Society were resumed on 
October 3rd, when the first part of a Memoii- on the Echinidai of the Chalk, 
by E. Cresy, Esq., was read. At the second meeting, on the 7 th ult., the 
reading of this paper was concluded. 
