296 Dr. Mac CulIoch on the Geology of Glen Tiff, 



no light on those Interesting appearances In the bed of the Tilt 

 from which it is so remote, and which are the principal objects 

 of this paper. It is sufficient to say in general, that it consists of 

 the several varieties of schist already noticed, which will doubt- 

 less be found associated both with quartz rock and limestone, 

 and reposing somewhere on granite, as the other parts which I 

 have really examined are found to do. 



On the declivity of the hill above Gow's Bridge the schist and 

 quartz rock may be seen irregularly alternating with each other and 

 with the limestone. On the hill Stron na 'Chro the green marble 

 beds are found at a considerable elevation, associated, as they are 

 below, with these rocks, being in fact the continuation of that series 

 of beds, the dip of which however various in the quantity of the 

 angle, is always in a southern direction. A little higher in the 

 hill the granite occurs : it is of a red colour, and precisely similar 

 in character to that which is observed throughout the bed of the 

 Tilt, and which I have already described. 



The burn Aldcriny having worn a deep channel In the rocks, it 

 IS easy to see the granite for a considerable extent/// situ; and Its 

 connections which are visible at the lower part of the channel 

 of the Criny having been described before, I need not here repeat 

 them. 



The granite continues along the ridge to Grianan, and is ac- 

 companied by quartz rock, of which the connection with the gra- 

 nite is unintelligible in the hill, however It may hereafter be ex- 

 plained by comparison with other observations. This rock itself 

 is of a very compact and somewhat transparent quartz, containing 

 irregular grains of felspar : it breaks in a flaky manner, and ap-' 

 pears to consist 6f beds extended in a north-easterly direction, and 

 dipping to the westward of north. It is impossible^ however^ 



