NICOL SOUTHERN GRAMPIANS. 



201 



in the lower valleys by detritus and occa- 

 sional convolutions. North of the Inn at 

 the Spittal I found a black carbonaceous 

 shale, in highly contorted beds, but dipping 

 60° to N. 12° W. This rock closely resem- 

 bles the black shales of Oban and Easdale, 

 described by me in 1858*. It appears to 

 overlie the mica-slate, and thus confirms 

 the view that the clay-slates are the higher 

 and newer formationf. The part of the 

 section, however, to which I wish specially 

 to refer lies further up the glen, and on to 

 the Braemar Mountains. The slates con- 

 tinue up Glen Beg to the foot of the steep 

 pass over the Craig AVell. Here a bed of 

 bluish-grey limestone, with numerous veins 

 of calc-spar, crops out, dipping at a high 

 angle to the north-west. This is overlain 

 by beds of gneiss passing up into quartzite, 

 which forms the higher portion of the 

 mountains. Near the summit-level of the 

 ridge veins of red felspar-porphyry are seen, 

 running from E. 30° to 35° N. to W. 30° to 

 35° 8. Further down, near Ben Turk 

 Bridge, a grey micaceous limestone appears, 

 dipping at 70° to S. 45° E. From this place 

 to Braemar the lower part of the valley con- 

 sists of gneiss, with veins of granite, but 

 overlain by beds of blue or grey compact 

 limestone, and this in turn by a white 

 quartzite or altered sandstone, often much 

 iron-tinged. The whole of the formations 

 seem to be conformable, and though occa- 

 sional high angles occur, yet taken generally 

 they dip at low angles to the south-east. 

 The gneiss appears merely the more meta- 

 morphic lower portion, and the quartzite 

 the less metamorphic and higher portion of 

 one great formation. Further north, beyond 

 the River Dee, as shown in the section, it 

 rests, still at very low angles of from 5° to 

 10° or 15°, on the granite of the Ben-Mac- 



2 o 







Cb 



s 



°5 





V 



-J 





M 



pq 



* Quart. Journ. Geol. Soc. vol. xv. (1858) p. 111. 



t I described this rock at the Meeting of the Bri- 

 tish Association in Aberdeen in 1859 (see Eeport of 

 that Meeting, Transactions of the Sections, p. 118), 

 and exhibited some fine specimens presented by Mrs. 

 Farquharson of Invercauld. It has since formed 

 the subject of a paper by Sir E. I. Murchison and 

 Mr. G-eikie, Quart. Journ. Geol. Soc. vol. xvii. (1861) 

 pp. 226 & 232. 





