﻿1851.] MURCHISON SILURIAN ROCKS OF SCOTLAND. 



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quharran (fig. 1). Mounting over the slope 

 for some little space which is obscured by 

 vegetation, fragments of finely laminated 

 schist are next observed to be associated 

 with coarse gritty greywacke. Presently the 

 knobby summit of the Brae is seen to con- 

 sist of a conglomerate (No. 2), containing 

 pebbles of quartz-rock and jasper, which is 

 underlaid by flaggy sandstone, the whole 

 being tilted off to the north by a boss of 

 greenstone. This conglomerate has no di- 

 stinct relations to the Silurian strata of 

 Saugh Hill, nor does it resemble in litholo- 

 gical composition a very coarse conglomerate 

 which will afterwards be described as occur- 

 ring at Kennedy's Pass. I am, however, of 

 opinion that it is of Silurian age, because 

 somewhat similar pebble-beds are found in 

 the shelly sandstone of Saugh Hill with a 

 reversed dip. In describing the coast sec- 

 tion (fig. 3), it will also afterwards be shown 

 that such conglomerates to the south of 

 Shalloch are intimately associated with true 

 Silurian strata. 



A zone of marshy land here indicates a 

 line of dislocation which probably consti- 

 tutes another axial line. Some of the lowest 

 beds of the north-western face of this hill, 

 as exposed in a deep gully, are finely mi- 

 caceous schists, occasionally containing cry- 

 stals of iron-pyrites. These again are fol- 

 lowed by shelly sandstones and here and 

 there a bastard limestone, with a few peb- 

 bles in some of the beds, in which fossils 

 occur in quarries opened out to the eastward 

 for the construction of stone walls. The 

 strike of these beds is persistently from 

 E.N.E. and W.S.W. Many of the fossils 

 are the same as those on the north bank of 

 the Girvan ; but, in addition to Atrypa he- 

 misphcerica, Sow., and other characteristic 

 Lower Silurian forms, we here detect the 

 Tent acuities ornatus and the Pentamerus 

 oblongus of the ' Silurian System.' 



Near the highest point of Saugh Hill the 

 strata are very highly inclined, viz. 80° to 

 the S.S.E., and even on the escarpment side 

 they dip as high as 65° to 70°, but with an 

 inclination always southerly : and thus a 

 great thickness of strata is evidently contained in this one hill. In 



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