Vol. 60.] OF THE EAST-CENTRAL HIGHLANDS. 421 



the first outcrop of the Limestone. Between this point and the next 

 bridge, a distance of 250 yards, the Limestone is repeated no less 

 than seven times by folding. As before, no two of these outcrops 

 are exactly alike ; but in this case the apparent suddenness of the 

 change is considerably increased, owing to the fact that we now 

 cross the folds at right angles. Certain materials, such as pale 

 hornblende, calcite, granular sphene, etc., are rarely wanting : 

 niicrocline may be either abundant or absent. The second out- 

 crop, above the lower bridge, is mainly composed of very pale-green 

 hornblende, while that next the small mass of hornblende-schist 

 contains idocrase, garnet, and pyroxene. Below the hornblende- 

 schist the limestone is coarsely mottled green-and-white, the green 

 patches consisting of radial bundles of pale hornblende. The western- 

 most outcrop is a nearly-white and rather siliceous limestone, 

 identical with' that seen in several places below Gilbert's Bridge, 

 and in man}' other localities ; while that part of the Moine Gneiss 

 which is next the Limestone is also highly quartzose. 



Again, as in the Gilbert's-Bridge section, small patches of Dark 

 Schist, varying both in thickness and composition, occur locally 

 between the Limestone and the Moine Gneiss. The ' Pink Bock ' is 

 also present in one place, commencing as a thin infold at either end 

 ■of the small mass of hornblende-schist, and thickening towards the 

 centre of the outcrop. Here it seems to merge insensibly into the 

 top of the Moine Gneiss, which just appears, in the bed of the 

 river (10,521). 



(d) The Hiatus in the Succession. 



The rocks associated together in the sections hitherto described 

 are as follows : — 



1. The Limestone. 



2. The Dark Schist (in lenticles). 



3. The Pink Felspathic Rock. 



4. The Moine Gneisses ; elsewhere the Honestones. 



5. The Epidiorite-sill, not always at the same horizon. 



(5. The white edge of the Quartzite, succeeded by the main bed. 



It has already been noted that the Limestone may be in contact 

 with any of the first five bands, and in one place it almost touches 

 the last, if it does not quite do so. There must consequently 

 be a small hiatus or line of erosion at the base of the Limestone. 

 But, in addition to the bands enumerated above, there are others 

 present in certain parts of the Aberdeenshire area, and apparently 

 absent here. It is consequently advisable now to fix exactly the 

 order of succession of the rocks, to ascertain the extent of the 

 hiatus, and see how far it throws anv doubt on the fact that we 

 are dealing in the main with a regular succession. As the full 

 sequence is exposed in the area south of Braemar, which lies in the 

 belt of ground under investigation, this succession in the Braemar 

 area may now be conveniently described. 



Q. J. G. S. No. 240. 2 g 



