THE PERMIAN ROCKS OF THE CLYDE DRAINAGE 



AREA. 



.... 



By JOHN SMITH. 



As observed by Sedgwick, Binney, Harkness, and Goodchild, the Permian 

 rocks of England are unconformable to the underlying strata, and the patches 

 of this formation in the Clyde drainage area occupy a similar position. 



BALLANTRAE DISTRICT. 



Just north of Ballantrae harbour and on the shore, there is a narrow patch 

 of Permian rocks. It consists of (a) a subangular conglomerate of a reddish 

 tinge at parts bound together with calcite, the contained pebbles being 

 evidently derived from the local Silurian rocks, greywacke, and trap, and 

 having suffered very little tear and wear, generally no more than their 

 angles having been removed. (6) From a short way N. of the harbour and 

 on to near Bennane Head there is an exposure of fine-grained red sandstone 

 closely resembling that of Mauchline. The beds dip gently, and are fre- 

 quently cross-bedded and ripple-marked. It is so soft that the recent mollusc 

 Pholas crispata bores freely into it. 



These beds have been bored for coal, and fresh water issues from a bore- 

 hole under high-tide mark. They terminate abruptly a short distance 

 inland, and may be faulted against the Silurians. A few narrow trap dykes 

 cut through them. 



MAUCHLINE DISTRICT. 



The Permian rocks of this district occupy a " pear-shaped " area, 9 miles 

 by 6 at its widest part. The lower beds consist of a series of " porphyrites, 

 melaphyres and tuffs, the product of volcanic vents which were active during 

 the earlier part of the Permian period." ("Explanation" sheet 14, Geol. 

 Survey.) They form a ring with an average width of less than a mile, and 

 doubtless extend under the red sandstones, which at parts are seen to 

 rest on them. There is, however, no definite line of junction, the tuft' dove- 

 tailing into the sandstone lying above it. 



The Permian sandstone is well exposed on the Water of Ayr at Balloch- 

 myle and Barskimming ; on the Lugar Water, near Auchinleck ; and in 

 several large quarries near Mauchline. It resembles that of the Ballantrae 

 district, and probably is largely a subaerial formation, although some of it as 

 exposed in the railway cutting between Mauchline station and the Mossgiel 

 tunnel has evidently been laid down in water. The thickness of this patch 

 is not known, but is at least several hundreds of feet. Towards its 

 upper part, bombs of the characteristic Permian volcanic, steatitic, and 

 tender amygdaloidal rock occur in the sandstone, showing that towards 



