IV GLEN TILT. 309 



12. In some of these rocks, the sienite is seen in contact 

 with various materials of the primary strata, and it was our 

 particular object, to examine the phenomena in such cases. 

 But, before I enter upon a detailed account of them, it 

 may be of use to give a general sketch of this part of the val- 

 ley. 



13. Glen Tilt, for about two miles below Forest Lodge, and 

 for three miles above it, to the junction of the River Chlochan, 

 runs nearly in a straight line, in the direction of N. from 

 46° to 48o E., and therefore not far from N. E. and S. W. 



14. The elevation of this part of the valley is considerable. 

 According to General Roy's measurement, the lawn at 

 Blair is 425 feet above the level of the sea ; and Mr Play- 

 fair's observations with the barometer, indicated the dif- 

 ference of level between Blair and Forest Lodge to be 

 about 400 feet. At the time of these observations, the baro^ 

 meter was falling, and the result is consequently too great ; but 

 after allowing for any probable error in excess on this account, 

 the height of Forest Lodge above the seia can hardly be esti- 

 mated at less than 700 feet. 



15. The bottom of the valley is narrow, rarely exceeding a 

 furlong in breadth, and generally much less. The lowest 

 banks of the mountains rise on either side with very steep 

 declivities ; on the south-east, to the height of from 600 to 

 800 feet above the river ; on the north-west, to between 

 1000 and 1200 feet. They are not cut by any lateral val- 

 leys ; except, that on the south-east side, two or three deep 

 ravines, descending from the sides of Ben y Gloe, join Glen 

 Tilt between Glen Chlochan and Forest Lodge ; and on the 

 north-west side, a mile and a half above the Lodge, a brook, 

 called the Crochie *, has deeply indented the ridge of the moun- 



VoL. VII. P. II. Rr tain, 



* This stream is caLed in the country Auld Crochie. ^aWsignifies brook in 

 Gaelic. 



