01^ CONTACT-ALTEKATION NEAE NEW GALLOWAY. 569 



35. Contact- Alteeation 7iear New Galloway. By Miss M. I. 

 Gakbinee, Science-Mistress, St. Leonard's School, St. Andrews. 

 (Eead May 14tli, 1890.) 



(Communicated by J. J. H. Teall, Esq., M.A., F.G.S.) 



[Plate XXIII.] 



Contents. 



1. Introduction. 



2. The Knocknairling-Burn Section. 



3. Shales traced along their Strike to their Junction with the Granite. 



4. Plags and Grits traced along their Strike to the Junction. 



5. Chiastolite-mica Schists. 



6. Aplite Veins. 



7. Age of the Metamorphosed Rocks. 



8. Remarks. 

 Explanation of Plate. 



§ 1. Inteodtjction. 



The eastern end of the northern edge of the Cairnsmore-of-Pleet 

 granite-mass follows the crest of the Knocknairling Hill to the west 

 of New Galloway for about half a mile. The metamorphism of 

 the rocks of this hill has been briefly alluded to in the " Memoir Ex- 

 planatory of Sheet 9 of the Geological Survey of Scotland," p. 22, 

 but is so extreme as to deserve a fuller description. 



There are many exposures on the hill-side ; and the Knocknairling 

 Burn gives a good section across the series at a distance of about 

 half a mile from the granite. It is a pity that the beds cannot be 

 traced farther from the granite, especially as there is some doubt as 

 to the series to which they belong. The Cairnsmore-of-Eleet 

 granite is some twelve miles by six in extent, with its greatest 

 elongation in the direction of the prevalent strike of the Silurians. 

 The Survey has given the name of " Queensberry Grits " to the 

 series into which it has been intruded, but suggests that the altered 

 rocks of Knocknairling Hill consist of the underlying Moffat shales 

 and Upper Ardwells, brought up here during the folding of the 

 district. The Upper Ardwells, where unaltered, to the east of the 

 granite, consist of rapidly alternating flags, shales, and greywackes. 

 The flags and shales are often sandy and micaceous. The grey- 

 wackes do not seem to differ from those of the overlying Queensberry 

 Grits. 



§ 2. The Knocknaieli^g-Bfen^ Section. 



In working up the Knocknairling Burn from Wauk Mill (see 

 Map, fig. 1) one crosses first beds of grits altered to a varying 

 extent. Parts are grey and very like unaltered grits farther east ; 

 but the greater part has the tint described as " purplish brown " by 



