OVEELYING ROCKS OE LOCH MAREE. 815 



On examination I found these upper beds everywhere unaltered, 

 except near dykes, and the change there induced in them was that 

 now well known as partial or contact-alteration, and which is so 

 entirely distinct from true or general metamorphism. These beds all 

 dip to theS.E. at a low angle, and attain a thickness of several thou- 

 sand feet. They are flag-like in character, and are made up chiefly 

 of fragmentary materials, but are occasionally slightly calcareous. 

 They are much like some of the Lower Silurian flags in Wales, and 

 are in no degree more highly altered than many of those rocks in 

 the more disturbed districts. They may be traced along both sides 

 of Glyn Docherty, but are dropped to a lower horizon on the south 

 side by the fault which extends from here through Loch Maree in 

 a line almost from N.W. to S.E.* On the north side of the road 

 in Glyn Docherty, about two miles from Kinloch Ewe, and almost 

 at the base of the hill, the lower beds have been denuded by streams 

 of water from the higher ground, the channels being, at the time of 

 my visit, almost dry. 



On examining these beds I found that the rocks were very unlike 

 those along the hillside on the higher levels, and which I had 

 traced forward continuously from Glyn Laggan. They were evi- 

 dently much more allied to the gneiss of the west side of Loch 

 Maree ; and the strike proved to be, as in the latter, from IsT.W. to 

 S.E., and hence in an entirely opposite direction to that in the 

 higher beds. This offered the clue which enabled me afterwards to 

 arrive at the conclusions which this paper is chiefly intended to 

 convey. 



This lower series in Glyn Docherty has apparently escaped the 

 observation of all previous writers ; and I was surprised to find, on 

 further examination, that this discordancy in strike and dip was not 

 confined to this one point, but that it occurred continuously for several 

 miles, or at least from near Kinloch Ewe to what is called the top 

 of Glyn Docherty, the highest point on the road to Auchnasheen. 

 These gneiss rocks keep at a low horizon for about four miles, or 

 until we reach the top of the Glyn. At this place they assume a 

 reddish granitoid appearance, and ascend considerably higher into 

 the hill. 



Eor the next few miles they are traced with more difficulty, and 

 probably faulted, but rise up again into the mountains as we ap- 

 proach Auchnasheen. 



The upper or overlying beds (/) are entirely lost at the ravine which 

 separates these hills from Ben Pyn and the range of mountains be- 

 hind Auchnasheen. I was unable to trace the limits of these upper 

 beds on the south of Glyn Docherty and of the valley of Loch 

 Bosque ; but from distant appearance I thought they extended 

 further east for several miles on that side than on the north side. 

 I had, previous to this, ascended Ben Eyn from Auchnasheen, and 

 carefully noted the rocks which were there exposed. I was then 

 surprised to find that they were almost identical in character with 

 the gneiss rocks of Loch Maree and Gairloch. 



I now again ascended Ben Fyn along a ravine a little IST.W. of 



