﻿1861.] 



MTJKCHISON AND GEIKIE — HIGHLANDS. 



225 



"We ascended Glen Tilt as far as the Forest Lodge, where one of 

 us climbed the precipitous hill that forms the eastern side of the 

 glen. The whole of this region has been so minutely described by 

 the fathers of Scottish geology that we shall not venture to offer any 

 details, further than that the section of the east side of the glen, 

 opposite the Forest Lodge, shows very clearly that the limestone, 

 after sundry intercalations of schist, is overlain by a thick, massive, 

 white quartz-rock. This rock ought to be found in the Garry, but 

 we could not detect it, unless the hard thick-bedded grey quartz- 

 rock at Ault Clune, two miles below Blair, be its representative. 



In the valley of the Garry at Blair and below it, there are pro- 

 bably at least two zones of limestone, one underlying the quartz- 

 rock, as does the limestone of Loch Bannoch, as well as that of 

 Glen Tilt, the other overlying the quartz-rock, like that of Loch 

 Kinardochy ; but the whole of the sections in this part of the river 

 are very obscure*. 



Blair to Dunkeld. — Passing over the obscured and doubtful ground 

 in the valley of the Garry below Blair- Atholl, we eventually meet 

 with quartzose and schistose strata, considerably contorted ; they are 

 seen here and there in the bed of the stream, particularly at the 

 bridge above the romantic Pass of Killiecrankie. About three miles 

 and a half below Ault Clune, they change their dip from S.E. to 

 The series is then repeated ; and at Pitlochrie the lime- 

 stone comes up again. From this point the latter rock strikes 

 across the hills in a north-easterly direction across Strath Ardle to 

 Glenshee, and thence into Glen Isla. How far it extends to the 

 south-west we did not ascertain. At the Pitlochrie quarry, the dip 

 is 1ST. 10° E. 



The valley south of Pitlochrie, judging from the scanty sections 

 to be seen by the wayside, appears to run for two or three miles 

 upon the flagstones that underlie the limestone ; two miles south 

 from that village a quarry has been opened in a micaceous quartzose 

 flagstone, which there dips N. 30° E. at 15° ; and similar strata are 

 occasionally seen in the channels of the smaller streams that descend 

 into the Tummel. These quartzose strata probably roll over again to 

 the south-east ; for we soon come upon the schists. But the valley 

 is much obscured by alluvium, especially after the junction of the 

 Tummel with the Tay ; and the time at our disposal did not allow of 

 excursions on either side of the Strath, to settle the relative boun- 

 dary-lines. 



At Dunkeld the upper schistose series is displayed in force. The 

 great quarries south of Birnam have been opened in grey slate, the 

 beds of which dip N. 70° W. at 65°, and are traversed by a cleavage 

 (much less perfect than that of Easdale), the planes of which are 

 inclined in the same direction at 55°. 



* Since our observations were made, we have communicated with Prof. Hark- 

 ne33, and have found that he has detected the upper limestone skirting the flanks 

 of the Ben-y-Grloe Mountains, not far above Blair. His observations on this 

 district will form part of the paper already alluded to. As shown in the test, 

 we also met with the upper limestone at the Spittal of GHenshee ; but this is at a 

 considerable distance from the Garry valley. 



