1862.] HAEKNESS METAMOBPHIC ROCKS. 341 



few merely local dips, there obtains through Sutherland the south- 

 east inclination of strata which prevails so extensively through the 

 metamorphic rocks of the North of Scotland. 



The metamorphic rocks of East Sutherland and the Scarabins ex- 

 hibiting a dip which, on the whole, may be regarded as having a 

 S.E. direction, the arrangement of the strata which compose these 

 rocks is a question which now presents itself. Under ordinary cir- 

 cumstances a section from Strath Naver, south-eastward over the 

 Scarabins, would furnish us with a sequence of rocks consisting of 

 lower members composed of flaggy gneiss, having in the higher 

 portions numerous granite-masses corresponding in direction with 

 the strike of the altered sedimentary rocks, and with these the 

 gneissic rocks assuming a more crystalline character. Upon these 

 gneissic rocks would repose the quartz -rocks of the Scarabins, suc- 

 ceeded also by gneiss. That this is not the true sequence of the 

 deposits may be inferred from the arrangements which rocks having 

 a like mineral nature present in other parts of the North of Scotland, 

 and in the Highlands generally. We have also, in many areas 

 where the metamorphic rocks are seen in Scotland, a sequence and 

 an arrangement which accord with those of the Scarabins and the 

 East Sutherland rocks. The circumstances under which the rocks 

 exhibit themselves in the section along the Banflshire coast have an 

 intimate agreement with those of the area under consideration, and 

 induce the conclusion that, so far from the flaggy gneiss forming the 

 lowest member of the series between Strath Naver and the eastern 

 flanks of the Scarabins, it occupies a position superior to the quartz - 

 rocks. In this area we have another instance of those rolls in the 

 strata which form axes of the inferior quartz-rocks, but which, in 

 consequence of having the plane of the axis depressed towards the 

 N.W., invert the superior gneiss on the N.W. side of the axis, and 

 by so doing give to the superior gneissic strata a position which 

 places them in the condition of apparently dipping underneath strata 

 upon which they really repose. These circumstances being taken 

 into consideration enable us to infer that the metamorphic rocks of 

 this portion of Scotland are referable to the series which is so well 

 developed in the western portions of Sutherland, and that here we 

 have the quartz-rocks of the Scarabins succeeded by the '' upper or 

 flaggy gneiss " of Murchison as in the west parts of this country. 



The mode in which the granites are associated with the meta- 

 morphic rocks in the area under consideration is a matter of consi- 

 derable interest. The correspondence of the strike of the plutonic 

 masses with that of the metamorphic rocks has been noticed in 

 connexion with these several rocks in Banfishire. In Sutherland it 

 is even more apparent, and supports the inference that here plutonic 

 masses do not perform the office of axes. Their mode of occurrence 

 rather tends to the conclusion that the sedimentary rocks were 

 elevated, flexured, and contorted previous to the period when the 

 granites made their appearance in the sedimentary rocks, and that 

 these granites have conformed in their course to the strike of the 

 previously elevated strata. 



2a2 



