IN GLEN TILT. 



341 



about half an inch broad, at length meets a thick stratum of 

 grey limestone, in which, after penetrating for an inch or two, 

 it branches out into small tapering veins, and is lost altoge- 

 ther. 



97. On the northern bank (at 10) a large vein of white fel- 

 spar crosses a part of the strata. Its thickness varies, but is 

 in some places between one and two feet. 



98. In the veins of sienite, or its gradations, throughout the 

 rocks I have been describing, shifts are not uncommon. 



99. Beyond the body of strata last described, the rock on 

 the southern bank is lost beneath the soil for a considerable 

 distance, and on the northern it appears only in some small 

 portions of strata, in which we did not observe any thing of 

 importance. 



100. It will be seen, from the plan of the river, that both 

 the strata and the sienite occur frequently in the intervals be- 

 tween the spots upon which I have dwelt so long ; but there 

 is no other considerable section of the rock, nor are the strata 

 and the sienite often seen in contact. In every other rock, in 

 which we observed a junction of them, the appearances are 

 quite analogous to those that have been described. 



101. Above the bridge also, for about a mile and a half, and 

 considerably beyond the junction of the Crochie, the rock 

 where it appears in the bed of the river, consists either of sie- 

 nite, or of granular quartz, gneiss, and other stratified substan- 

 ces, of the same characters with those already mentioned. 

 The strata are occasionally intersected by veins of the red sie- 

 nite. 



Vol. VIL P. II. X x 102,; The 



