﻿1851.] MURCHISON — SILURIAN ROCKS OF SCOTLAND. 



143 



of Dalquharran, and are seen between them and the foot of Mulloch 

 Hill, as represented in the diagram fig. 1 (<?**). These fossils are, 

 Productus giganteus, Sow., P. Martini, Sow., Nautilus tuberculatus, 

 Sow , Spirifer, probably S. trigonalis, Sow., and a Coral. 



By such clear proofs we now clearly know, that the Girvan Water 

 coal lies low in the carboniferous system ; since it is inferior to bands 

 of limestone charged with unequivocal mountain limestone species. 

 These coal beds have thus the same position as the chief carboniferous 

 masses of Berwickshire and many parts of the south and centre of 

 Scotland, as well as those of Russia and other countries, so clearly 

 distinguished from the main coal-fields of England, which are super- 

 posed to the marine formation of that sera, or the lowest carboni- 

 ferous division. 



The sections figs. 1 & 2 will lead the reader to see, that the coal 

 strata of the Girvan Water Valley have been subjected to very great 

 dislocations subsequent to their deposition in a trough of those Silurian 

 Rocks which I now proceed to consider. 



Silurian ridges on the right bank of the Girvan Water. — 

 Although the Silurian rocks are best exposed on the S. bank of 

 the Girvan, where the hills are higher, and where some of the strata 

 are seen in scars along the shore, I will first describe the hills N. of 

 the Girvan, as I desire to carry the reader with me in an examination 

 of the strata from north to south. 



The rocks constituting the Silurian series of Ayrshire consist of 

 (3) schists and limestones, (2) shelly greywacke sandstone with con- 

 glomerates, and (1) limestone and schists; and in the sequel it will 

 be indicated that such is the ascending order of the deposits (see 

 Table on the Map). 



These ridges are composed of strata which strike from W.S.W. to 

 E.N.E., or parallel to the general direction of the Silurian rocks of 

 the S. of Scotland. The Girvan Water and the Stinchar (of which 

 hereafter) flow in longitudinal depressions or fissures which are also 

 coincident with the strike of the rocks. 



The dominant rock in these low hills is a sandstone, in some 

 parts of a grey, in others of a reddish, iron-shot colour, which 

 abounds in shells and casts of shells. Whether its fossils or the 

 lithological character of the rock be regarded, I did not doubt, on a 

 first inspection, that it represented the Caradoc sandstone ; for many 

 of the rock-specimens from Ayrshire might be labelled Ankerdine 

 Hill, or May Hill ; places where that formation, as described by my- 

 self, assumes a clear and typical aspect in the original Silurian re- 

 gion. On the slopes of Mulloch Hill, above Dalquharran, this 

 shelly sandstone dips sharply to the S.S.E. in several quarries which 

 have been opened ; but in passing over that low eminence the strata 

 are seen to turn and dip also to the N. and W. The open quarries 

 above the Rough Neuk, High Mains, &c, exhibit this shelly sand- 

 stone dipping 40° to the S.S.E. The prolongation of this dip of 

 the older rock must therefore cut off the coal. In truth, however, 

 there is every reason to suppose that some of the space between the 

 carboniferous and Silurian rocks is occupied by an igneous rock ; 



