176 
PROFESSOR T. J. JEHU AND DR ROBERT CAMPBELL ON 
tions and maps the Highland Border Rocks are taken as forming a part of the meta- 
morphic complex of the Southern Highlands, though it is often recognised that for 
the most part they are not so much altered as those occurring to the north. We 
shall note only some of the more important publications which have a direct bearing 
on the series under consideration. 
Professor James Nicol in his Guide to the Geology of Scotland (1844) noted the 
close resemblance of some of the Highland Rocks to the Silurian strata in the south 
of Scotland, and in a subsequent paper communicated to the Geological Society of 
London in 1849, referring to the band of clay-slate extending from Stonehaven to 
Arran, he says, “this band of slate may form the continuation of the Silurian beds 
on the south, rising up on the other side of the synclinal valley in which the Car- 
boniferous strata of Scotland have been deposited.” * 
In 1863 Nicol in a paper “ On the Geological Structure of the Southern Gram- 
pians ” t described a series of sections traversing the southern margin of the High- 
lands at various places from Bute north-eastwards to Forfarshire. In the south-west 
of Scotland the grits and shales on the southern margin of the Highlands are shown to 
be dipping towards the south-east and to overlie the rocks to the north ; immedi- 
ately to the east of Loch Lomond these beds dip at angles approaching the vertical, 
and from the Pass of Leny and Callander north-eastwards the dip is to the north- 
west, and so the beds appear to pass under the rocks of the Highlands to the north. 
He expressed the belief that the normal sequence is that seen in Bute, and that as 
the marginal belt is followed north-eastwards a reversion of the strata takes place. 
Though he does not refer specifically to the rocks in the Aberfoyle district, it is 
obvious that he regards the apparent dip of these rocks under the more meta- 
morphosed rocks to the north as abnormal. 
In this paper Nicol concludes that the rocks of the Southern Highlands are in 
the main more ancient than those in the South of Scotland, but he expressly notes 
the unaltered character of some of the rocks of the marginal belt, for, in referring to 
the section at Leny Old Lime Quarry, Callander, he remarks that “ both the texture 
and colour of the limestone, and the black carbonaceous-looking shales associated with 
it, remind us rather of the Carboniferous formations than of a primary deposit.” + 
In 1891 Sir Archibald Geikie in his Presidential Address to the Geological Society 
of London § gives a table showing in the apparent descending order the various sub- 
divisions of the rocks in the Highlands of Perthshire recognised by members of the 
Geological Survey. The group which we now term the Highland Border Rocks is 
placed as the base of the column underlying, and so presumably older than, all the 
other formations. 
In the Annual Reports of the Geological Survey from 1893 onwards we find 
valuable summaries of the work carried on along this marginal belt of rocks. The 
* Qua/rt. Journ. Geol. Soc., vol. vi, p. 60, 1850. 
J Ibid., p. 187. 
f Ibid., vol. xix, p. 180, 1863. 
§ Ibid., vol. xlvii, p. 74, 1891. 
