442 MI{. E. M. ANDERSON OX THE GEOLOGY OF [vol. lxxix, 



is discordant, both as regards the zones of the Dalradian and those 

 within the flags. This discordance appears from the evidence to lie 

 more probably due to a folded rupture than to an unconformity, 

 although I do not claim that the facts which support this con- 

 clusion form an absolute proof. 



The study of this district has strengthened my belief that large 

 horizontal movements have affected the Southern Highlands. 

 These may, or may not, be connected with the appearances of 

 flow-structure. At the same time, I think it as yet impossible to 

 define their direction, or to say whether the discordances which 

 they appear to produce need in every case have been due to 

 thrusting, rather than to the distortion of large normal faults. 

 In these respects I regard the subject as being at present in the 

 speculative stage. 



EXPLANATION OF PLATE XXV. 



Geological map of the Schichallion district on the scale of 1 inch to the mile, 

 or 1 : 63,360 ; and section across the same. 



Discussion. 



Dr. J. S. Flett said that this paper appeared to be an elabo- 

 rately careful piece of work. It was of interest, as the Author's 

 version of the sequence was in some respects different from that 

 of Grant Wilson, and more complete. Two points especially 

 attracted attention. One was the presumably upward sequence 

 from the margin of the Moine rocks : this was in accordance with 

 the views of other geologists Avho had recently been working on 

 that group. The second point touched the relations between the 

 Moine Series and the rocks south thereof. On this question the 

 Author had, unfortunately, formulated no definite conclusion. An 

 examination of the Author's map suggested that this line might 

 mark a plane of movement ; but, before it was assumed that the 

 absence of certain groups was due to that cause, it was desirable to 

 bring forward some evidence that these rocks had originally been 

 deposited there, and had not subsequently been removed by erosion. 

 Several features of the map, especially the Boulder Bed and its 

 local distribution, suggested that contemporaneous erosion or non- 

 sequences might be expected in that group. 



Mr. Gr. Barrow drew attention to the difficulty of dealing 

 with the details of recent papers on the Highland rocks, as new 

 names were introduced for every new locality visited. With 

 regard to the succession in the beds described in more detail in 

 the Author's paper, certain facts were now well established. The 

 pebbly portion of the Quartzite is the base of the bed, for it has 

 been proved to overlie directly the true Graphite-Schist over a 

 great stretch of ground. Beginning in South- West Aberdeen - 

 shire and coming south-west to Pitlochry, the speaker had noted 

 that the base of the Quartzite is often blackened by minute specks. 



