M4 GEOLOGICAL APPEARANCES 



fraction of an inch, to many £eet. The intervals exhibit 

 great diversity and irregularity in their forms ; but an ap- 

 proach to parallelism between the surfaces of the masses, 

 that lie nearest together, often gives to the interval the form 

 of a vein. In all the various sections of the rock formed by 

 the present surface, the intervals, whether above, below, or on 

 the sides of the masses, appear, with few exceptions, to be 

 completely filled, either with a sienite similar to that of the 

 main rocks, or with felspar, either pure, or mixed with other 

 substances, so as to present evident gradations from that sie- 

 nite. (Parag. from 51 to 54, from 58 to 60, 76, from 78 to 81, 

 84, 87, 88, 90, 92.) 



1 10. This appearance of separate masses of strata, with the 

 intervals filled with sienite, was observed only where the great 

 body of strata, and the main rocks of sienite, were each of 

 them at no great distance. (Parag. 3, 6, 7, 21, 22, from 24 to 

 28.) One or two exceptions, however, occurred farther up the 

 Glen * 



111. In several instances, the sienite and its gradations, 

 which appear, in the form of veins, among the stratified masses 

 resting upon the main rocks of sienite, were observed to join 

 to the main rocks of sienite, without any abrupt change of cha- 

 racter between the substance of the vein, and that of the main 

 rock below. (Parag. 52, 53, 79, 87, 88, 90.) 



112. The lines of junction between the stratified masses, and 

 the sienite, or its gradations, are in most cases definitely mark- 

 ed. (Parag. 50, 53, 59, 60, 75, from 78 to 81, 83, 87, 88, 



90, 



* See the latter part of parag. 135, and note D at the end of the paper. 



