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PROCEEDINGS OP THE GEOLOGICAL SOCIETY. 



[Feb. 6, 



evidence of the existence of an upper quartz-rock, under which the 

 limestone passed without any break*. 



Fourthly, I simply repeat the statement I previously made, that 

 there are the most essential distinctions between the old and funda- 

 mental gneiss of Loch Stack and Loch More on which tbe quartz- 

 rock and limestone repose, and the earthy and slightly micaceous 

 flagstones which overlie such rocks on Loch More, and specimens of 

 which to compare with the older gneiss are exhibited. See Professor 

 Nicol's section, fig. 6, and my section, vol. xvi. p. 226, fig. 6. Here 

 again the strike of the old or Laurentian gneiss (a) is nearly at right 

 angles to that of the overlying flag-like schists {cV) with which 

 Professor Isicol unites it. 



Fifthly, I am compelled to point out, in defending the correct- 

 ness of my own views as regards the relations of the rocks in Durness, 

 that the second of the sections of Professor Mcol (p. 87) is, on the 

 face of it, very inaccurate. The author gives this line of section as 

 proceeding from Far-out Head on the west to Kean-na-binn on the 

 east. Now the fact is, that this line is really from N". by "W. to 

 S. by E. (see Map of Sutherland and Admiralty Charts). Owing to 

 this error, the strata are necessarily placed in false positions ; for 

 those of the Far-out Head, and the promontories extending to the 

 Bishop's Castle, and which dip away to the east, are, as I have shown, 

 the overlying thinly laminated schists with white sandy micaceous 

 flagstones f, and are quite distinct, by position as well as structure, 

 from the nearest old granitic and hornblendic gneiss, which, striking 

 from N.N.W. to S.S.E., clips to the S.S.W. 



Sixthly, I would observe, that the section fig. 9, p. 100, from 

 Cnoc Chaorinie to Alt Ellag, as given by Professor Nicol, seems 

 essentially to sustain the proofs of the order of succession which I 

 have pointed out ; for in it we see a lower quartz-rock and limestone 

 followed conformably by overlying quartz-rocks and limestones, 

 whilst these are succeeded, also conformably, by chloritic schists. 

 The only difference between this section and my own view of the 

 succession in that tract is, that neither my companions nor myself J 

 could observe tbe fault or dislocation § which Professor Mcol has 



* See also Prof. Harkness' s sections in my memoir, Quart. Journ. Geol. Soc. 

 Aug. 1859, vol. xTi. p. 221, fig. 4, and p. 223, fig. 5. 



t Specimens of these thin flag-like sandy schists from this promontory were 

 exhibited at the Meeting to show their entire dissimilarity to the old gneiss of 

 Kean-na-binn and the ridge S. of Durine Inn, with which Prof. Isicol connects 

 them. 



J Professor Ramsay sedulously explored tliis locality by himself. 



§ In a letter recently addressed to me by Professor Harkness, in which he 

 points out other errors in the sections of Professor Nicol, which I do not here 

 mention, he thus alludes to the introduction by Professor Nicol of the fault near 

 Alt Ellag between the quartz-rocks and the overlying chloritic, micaceous, and 

 gneissose rocks: — "Of this fault suffice it to say, that there is not the slightest 

 evidence of any crack here." It has naturally given me great satisfaction to have 

 the support of such an able and. independent observer as Professor Harkness, 

 who, when he visited the west of Sutherland, after a discussion wliich had taken 

 place on those very points at the Aberdeen meeting of the British Association, 

 had, as he himself writes, " a stronger feeling towards Xicol than yourself, so 

 that I may be said to have to some extent prejudged the case ; when, however, 



