P. MACNAIR ON ROCKS OF HIGHLAND PERTHSHIRE. 169 
supposed to underlie these schists, and, with its limestones, to re¬ 
present their lower group. Passing now to their next traverse, namely, 
that from Dalnacardoch to Blair-Atholl, a great series of quartz 
rocks in an ascending order is described, terminating in the super¬ 
position of a very thick limestone series, two miles and a half from 
Blair. We quote the authors’ own words in description of the 
Blair-Atholl region :—“ In examining the south-western flanks of the 
Grampian chain near Blair-Atholl it was indeed quite manifest, 
judging even from the flaggy and schistose characters of the rocks, 
that we were already among strata superior at all events to the lower 
quartz rock and limestones of the north-west Glossy Shillat, while 
micaceous schists, resting upon granular quartz rocks and limestones, 
and even alternating with them, presented to the eye a mineral 
development unknown in the lower members of the altered Silurian 
rocks of the north-west, and wholly unlike anything in the Cambrian 
rocks and fundamental gneiss of the outer Hebrides and the west 
coast of Sutherland.” 
In concluding our review of these authors’ sections describing the 
relationship of the schists and quartzites of the southern Grampians, 
we would here notice their description of a traverse from the Spittal 
of Glenshee to Blairgowrie and from Blair-Atholl to Dunkeld. In 
the former of these we pass across a complete series of the rocks 
forming the southern Grampians, and as Nicol subsequently de¬ 
scribed the same section, it will be of some value to compare 
Murchison and Geikie’s work with that of Nicol. It is not very 
clear in Geikie and Murchison’s paper what they consider to be the 
exact relationships of the black schists of the Spittal of Glenshee and 
the quartzites of Ben-y-Ghloe to the mica-schists, quartz-schists, clay- 
slates, and greywackes along the margin of the Grampians, as seen to 
the north of Blairgowrie. But it is likely that they looked upon the 
Ben-y-Ghloe quartzite as underlying these other rocks in a similar way 
to the quartzite of Schiehallion and the region north of Blair-Atholl. 
The same remarks may be made regarding their description of 
the ground between Blair-Atholl and Dunkeld. It is here again 
difficult to discover what Murchison and Geikie exactly refer to 
their lower quartzose group, and what to their upper schistose group. 
The rocks around Dunkeld, consisting principally of schists, grits, 
and clay-slates, are referred to their upper schistose series, and thus 
the whole problem of these marginal rocks seems to have been 
evaded. 
It is unnecessary that we should enter into any further description 
of these sections, for what we have already given is sufficient to show 
that the main contention of these authors was that in the Southern 
Grampians we have a great series of quartzites overlaid by limestones 
