Relations of the Secondary Strata in the Isle of Arran. 29 



face of the hill, and are confusedly piled upon the steep ascent; and from hence 

 the same beds are continued in a low mural escarpment to North Sannox, 

 where the cliff disappears. This position has great geological interest : 1st, 

 because it is here that we must place the anticlinal axis of the coast section ; 

 2ndly, the primary schist thins out at this point, so that the old red sandstone 

 and conglomerate range for upwards of two miles high in Glen Sannox, and 

 may be traced even to the base of the serrated granitic ridge. Some of the 

 lowest beds of the conglomerate in this region assume the character of very 

 compact grauwacke slate ; and these, as well as others of the same age on the 

 shore, are traversed by dykes of very compact greenstone*. At Mid-Sannox 

 the cliff viewed from the sea is a mural escarpment of conglomerate, the lines 

 of stratification of which deviate little from horizontality ; but at South Sannox 

 the dip is decidedly reversed, being to the south of east. At the latter place 

 a low cliff of conglomerate and sandstone is broken into by frequent transverse 

 gullies, some of which may have been simply the result of denudation, whilst 

 others may have been fissures produced by the vicinity of the granite ; indeed 

 the shore here is encumbered with a vast accumulation of boulders of granite, 

 there being no longer any schistose range of mountains interposed between 

 the granitic nucleus and the coast to impede the transportation of these blocks. 

 At about one-third of a mile north of the village of Corry, the conglomerate 

 beds are surmounted by white and spotted sandstone, and an impure concre- 

 tionary limestone. As the latter is precisely similar in character to the corn- 

 stone described on the other side of the anticlinal axis near Groggan Point, its 

 existence in this situation is important in the verification of the ascending 

 series which we are now describing. This being the final appearance of the 

 old red sandstone on the coast, it may be necessary to add a few words re- 

 specting its general composition. On a great scale it is to be viewed as a red 

 conglomerate with many subordinate beds of sandstone, which cannot, either 

 from the nature of the pebbles or the cementing principle, be distinguished 

 fi'om the newer conglomei'ate ; neither can the sandstone of the one series be 

 described as differing from that of the other. The existence, however, in the 

 one deposit of beds of arenaceous grauwacke slate near the bottom, and that 

 of the cornstone in the upper part of the formation, strongly identify it with 

 the old red sandstone. Moreover, independently of any such distinctive cha- 

 racters, the intervention of the well developed groups of the carboniferous 

 series enables us with certainty to separate the two great deposits of conglo- 



* In the higher part of the burn at North Sannox, and very near the granitic nucleus, are large 

 masses of sulphate of barytes associated with the conglomerate, with which they appear to have 

 been contemporaneous. 



