300 mil e. b. bailey osr the [June 1913, 



Group, a non-calcareous mica-schist series, with many gritt}' 

 intercalations in which pebbles can often be recognized. The most 

 conspicuous' feature of the Garnetiferous Mica-Schist of the Loch 

 Pyne tract is the abundance of garnets, but this character fails 

 towards the south-west. The garnets, where present, are frequently 

 accompanied by actinolite. 



Towards the north-east, in the Loch Fyne district, the St. Cathe- 

 rine's Graphite-Schist has not been mapped outside of Cowal ; but 

 its presence has been recorded by Mr. Hill at one or two points 

 between Loch Eyne and Meall nan Tighearn. It is probable, 

 indeed, that the division-line laid down on the map to separate 

 the Ardrishaig Phyllites and the Garnetiferous Mica-Schist, in this 

 part of the area, follows an approximately constant horizon. 



Towards the south-east it is doubtful whether the St. Catherine's 

 Schist persists or no. A remarkable change of stratigraphy is 

 encountered in this direction : for a thick fine-grained quartzite 

 makes its appearance, situated in a general way between the Ardri- 

 shaig Phyllites and the Garnetiferous Mica-Schist. It is quite 

 certain that this quartzite, the Erins Quartzite as it is called, 

 belongs in part to the Ardrishaig Group, since its development 

 has been followed, more or less, stage by stage. ^Vliat is un- 

 certain is, whether any considerable proportion of it is equivalent 

 to the Garnetiferous Mica-Schist farther north. A thin grey 

 phyllitic division, the Stronehullin Phyllites, divides the Erins 

 Quartzite into two roughly equal portions ; and in it occurs a band 

 of graphitic phyllite, which Mr. Clough suggests may be correlated 

 with the St. Catherine's Graphite-Schist [18, p. 9] : this would 

 relegate the lower half of the Erins Quartzite to the Garnetiferous 

 Mica-Schist position. Mr. Hill, on the other hand, considers that 

 virtually all the Erins Quartzite belongs to the Ardrishaig Group. 

 The two portions of the Erins Quartzite are much alike ; pebbly beds 

 are rare, until the south-eastern border of the division is approached. 



The quartzite is very slightly calcareous, where tested, and 

 one or two bands of cream-coloured and grey limestone, several feet 

 thick, are found near its north-western limit ; even more important 

 beds of grey limestone occur near its south-eastern margin. 



The Shira Limestone, 



This limestone is a comparatively thin and inconstant division. 

 On the east side of the Loch Awe Syncline it is not appreciably 

 developed south of the Crinan Canal, connecting Crinan Loch with 

 Ardrishaig. North of the canal, however, the limestone is probably 

 continuous, although, not unnaturally, it is shown on the map as 

 having a broken outcrop. 



A very good section is afforded by the River Add, which crosses 

 the course of the Shira Limestone 5 miles north-north-east of 

 Ardrishaig,. The limestone occurs here in massive, cream-coloured, 

 banded sandy beds, which effervesce with acid ; some of the layers 

 merge into calcareous quartzite. On the east it is separated by a 



