126 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 4, 



character between the lower beds of quartz-rock, alternating with 

 micaceous schist, and the upper part, which is almost exclusively 

 siliceous, corresponds with what we should expect to find in a cry- 

 stallized Old Red Sandstone, of which the lower division is composed 

 in part of argillaceous beds fit to furnish the micaceous schist, and 

 the next division contains very little clay. 



The masses of quartz-rock which harmonize least with this arrange- 

 ment are those of Schiehallion, Ben Gloe, and the Scarabins ; if we 

 leave these in suspense, and only admit that the rest of the stratified 

 quartz-rocks belong to the Old Red Sandstone, it will still follow, 

 from the position of the various masses described, that that forma- 

 tion must have covered the southern portions of the Highlands at least 

 as far up as the Grampians. 



February 4, 1852. 



The Rev. J. Gunn was elected a Fellow. 



The following communications were read : — 



1. On the Southern Border of the Highlands o/" Scotland. 

 By D. Sharpe, Esq., F.R.S., V.P.G.S. 



Having lately visited many of the passes leading into the Highlands, 

 I found the arrangement of the rocks along the border so different 

 from what I had been led to expect by what has been published on 

 the subject, that I venture to offer the following remarks upon the 

 Border formations, although I am far from having materials for a 

 complete account of them. 



Mr. Nicol's * Guide to the Geology of Scotland ' gives us a good 

 summary of what was known on the subject up to 1844, and little or 

 nothing has been added since ; his account, therefore, will often be 

 referred to. 



In MacCuUoch's Map of Scotland a band of blue colour, indicating 

 "Clay-slate or Greywacke," stretches across Scotland from Stone- 

 haven to Bute and Arran, bounded on the south by the Old Red 

 Sandstone, and on the north by mica schist, and within this clay- 

 slate are represented the bands of limestone of Loch Lomond and 

 Aberfoyle. Mr. Nicol's map includes in the same band of clay-slate 

 the limestones of Callander and that on the South Esk near Cor- 

 tachie. Mr. Buist's Map of Perthshire, published in the forty-fifth 

 number of the Journal of the Highland Society, draws into the same 

 Clay-slate Formation the limestone between Dunkeld and Blair 

 Gowrie. These views are at least consistent, for there can be little 

 doubt that all these limestones are contemporaneous ; but, from the 

 visits I made to several of the quarries, I have no hesitation in refer- 

 ring them all to the Old Red Sandstone. Mr. Buist goes still far- 

 ther in favour of the clay-slate, carrying it up five or six miles north 

 of its real boundary to include in it some outlying patches of lime- 

 stone marked by MacCulloch, and thus colours as clay-slate a large 



