Vol. 60.] OF THE EA.ST-CENTRAL HIGHLANDS. 413 



the parallel-banded grey gneisses ; for the typical highly-chloritic 

 films of the latter were never present in the original quartzite. On 

 the splitting-face a thin film of fine, evenly-disseminated muscovite 

 is present, which gives rise to the flaggy aspect of the quartzose 

 gneiss. It was doubtless developed along buckling-planes from the 

 felspar in the Quartzite. This type of material is the dominant 

 constituent of the Moine Gneiss on the south side of the Dee, for a 

 considerable distance to the east. 



Approaching Braemar, the colour-banded pink-and-grey rocks 

 increase once more in amount ; but still, in small openings by the 

 roadside, portions of the true quartzite can be identified, despite the 

 new structure developed in it, by certain fine dark lines of heavy 

 minerals, to which special reference will be made in describing the 

 Quartzite. 



(c) Area south-east of the Cairngorm Granite. 



In that portion of Invercauld Forest which lies between the 

 Sluggan Burn and the ridge of Cairn Liath to the east, the Moine 

 Gneisses vary somewhat in appearance. Highlj'-quartzose rocks are 

 more abundant in the south-eastern part of this ground, and the 

 bands are distinctly thinner; but farther to the north-west they 

 thicken and, on the whole, become more felspathic and variable in 

 composition. Where thinner, they consist essentially of three small 

 bands : the first being practically quartzite, the second darker with 

 more brown mica, and the third a kind of pink-edged quartzite. 

 These three thin bands, by repeated foldings on themselves, form 

 great rock-masses, which can be admirably studied in the low crags 

 alongside the Sluggan-Burn footpath, at about a mile above the 

 junction with the Dee. 1 



A little to the south-east of these crags, it is again often 

 impossible to say where the Moine Gneisses end off and the Central- 

 Highland Quartzite begins : for the latter now occurs in a ' Moine- 

 phase.' The typical white margin of the latter can be identified on 

 the footpath above the house, near the northern end of the plan- 

 tations ; and, starting from this point, it is clear that the greater 

 part of the quartzose gneiss must be formed of the Main Quartzite. 



On the ridge between Meall Gorm and Cairn Liath, little but the 

 three quartzose bands already mentioned can be seen. The palest 

 band is met with first, and is just sufficiently banded to be separable 

 from the true Quartzite. Farther north the greyer band appears, 

 slowly becoming more felspathic and more like the typical grey 

 gneiss. On the southern part of Cairn Liath, the pink quartzose 

 band is the dominant rock, and must be folded on itself to an extent 

 that is almost incredible, to form so large a portion of this hill. 

 Farther west, the thickening and the change in composition are soon 

 well marked : the pink-edged rock in particular having darker and 

 more felspathic bands in it. One of these has a rather mottled 



1 See p. 435 for a description of these bands where the Moine structure is 

 not developed. 



