IN GLEN TILT. 



363 



140. The extent of the granite, and other crystallised aggre- 

 gates on this side of Glen Tilt, was farther confirmed by our 

 observations on the mountains more to the south, about Glen 

 Criny and Glen Merk. These mountains do not shejv much 

 of the fixed rock, and we were therefore left in most cases to 

 infer the materials of which they consist, from the loose blocks 

 that are scattered on their sides, and along the higher parts of 

 the courses of the streams. In order to make the account as 

 faithful as possible, I shall enumerate the substances that we 

 met with, in the different lines of our walks, beginning with 

 what lies nearest to Forest Lodge. 



14i. For a considerable distance from the Griurnon towai'ds 

 Cairn y Chlannan, along the broad ridge that joins them, I 

 found fragments of granular quartz, and a few of granite. The 

 summit of Cairn y Chlannan is granular quartz. To the south- 

 west of it, the ground falls into the head of Glen Criny, which 

 opens into Glen Tilt. 



142. lu ascending from the lower part of Glen Criny to- 

 wards the Griurnon, but winding to the north, so as to gain 

 the ridge that joins it to Cairn y Chlannan, I saw loose blocks 

 of granular quartz, and sienitic greenstone graduating into grey 

 sienite. This sienitic greenstone, and its gradations, resemble 

 those so abundant on the northern side of Glen Tilt, and in 

 the following pages the terms always denote similar substances. 

 Through the lower part of Glen Criny, the stream runs with a 

 very rapid fall, for between one and two miles, over red gra- 

 nite ; which, as far as I could judge from where the observa- 

 tion was made, extends to a point within two or three hundred 

 feet in perpendicular height, and perhaps a furlong in horizontal 

 distance, from the granular quartz that appears at the bridge over 

 the Criny in Glen Tilt. We regret that we had no opportunity of 

 examining the junction of the strata and the granite, in the 



channel 



