422 ON NEWER GNEISSIC ROCKS OF THE NORTHERN HIGHLANDS. 



zite, the flags, or the limestone ; but here and there the quartzite 

 rested in position upon the Arnaboll rock. The latter thus ap- 

 peared to occupy the stratigraphical place of the upper part of the 

 Hehridean ; and as other sections showed it to he followed at once by 

 the typical Hope schists without the intervention of the quartzite, 

 the Emboli sections appeared to support Dr. Callaway's view, that 

 the whole of the Sutherland series was Archaean. 



Dr. Hicks expected to hear some one rise to defend the views 

 maintained by the Geological Survey. The main results announced 

 by Dr. Callaway agreed very well with those at which he himself 

 had arrrived in the district further south. The most remarkable 

 thing in the Survey theory was that the more highly you ascended 

 in the succession the more altered the beds became. He was 

 extremely glad to find that the previous speakers, after careful 

 consideration, had arrived, like himself, at views which seemed so 

 much more natural, and that they agreed that the eastern gneiss was 

 not of Silurian but of Archaean age. 



Dr. Callaway, in reply to Mr. Hudleston, stated that the Caledo- 

 nian was certainly distinct from the Hebridean, since in Glen Coul 

 it rested upon the latter with a discordant strike. He had at first 

 been disposed to think that the Arnaboll gneiss was Hebridean, as 

 held by Prof. Lapworth ; but he had been led to abandon that view, 

 because between the Arnaboll gneiss and the overlying Hope series 

 there was (1) conformity of dip and strike, (2) an unbroken pas- 

 sage, and (3) a lithological gradation ; whereas in Assynt, where 

 the younger gneiss rested upon the Hebridean, there was a com- 

 plete discordance. He held, however, that if it should be found 

 necessary to revert to his original opinion, the case against the 

 old view would not be weakened, since, on that hypothesis, the 

 Assynt series would be made to dip conformably below both Hebri- 

 dean and Caledonian, which was absurd ; and since there was no 

 break between the two gneisses, it was obvious that the Assynt 

 rocks could not pass between them. 



