1852.] NICOL ON THE GEOLOGY OF CANTYRE. 425 



Professor Sedgwick, of the want of granite boulders in those of Arran. 

 Both rocks also abound in water-worn fragments of hard sandstones, 

 thus evidently belonging to some more ancient formation, though of 

 what age and where existing cannot now be determined. The date 

 of some portions of the red sandstones both in Arran and Cantyre is 

 very uncertain from the entire want of fossils. The distinguished 

 geologists just named, though now of a different opinion, and regard- 

 ing it as carboniferous, at one time considered the sandstone in the 

 south of Arran as the New Red Sandstone, whereas Dr. Macculloch 

 coloured the whole as Old Red, identical with that below the coal on 

 the opposite coast of Ayrshire. This is no doubt the true age of a 

 portion of that in Cantyre, though other parts, mentioned above as 

 probably contemporaneous with the felspar-porphyries, would in that 

 case be of newer date, and even posterior to the coal. In the absence 

 of organic remains, it is, however, impossible to determine their pre- 

 cise age, or their relation to the strata of other countries. 



The introduction of the large overlying mass of trap is the most 

 important change I have been able to make in the geological map of 

 this portion of Scotland. It has long been known that an almost 

 continuous band of igneous rocks traverses the country from the 

 German Ocean near Montrose to the island of Arran. Here 

 formerly it might have been supposed to terminate, the fragments 

 laid down by Macculloch near Campbeltown being comparatively 

 inconsiderable. Now, however, they are found to appear in full force 

 in the southern part of Cantyre, thus traversing the entire breadth 

 of Scotland, and connecting the trap-rocks of that country with those 

 in the north of Ireland. The age of the trap-rocks associated with 

 the Scottish coal-field is very uncertain, there being no more recent 

 formations with which their outburst can be compared. Could we 

 regard the igneous rocks in the north of Ireland as the true conti- 

 nuation of this band, its origin at a far more recent period than is 

 usually supposed would be so far rendered probable. The direction 

 of this band is approximately parallel to the southern Silurian rocks 

 and the northern mica-slates and clay-slates. This coincidence of the 

 lines of more recent igneous eruptions with lines of ancient upheaval 

 and fracture has been repeatedly observed, although, perhaps, rarely 

 on such an extensive scale. The length of this band even in Scot- 

 land alone is above 150 miles in a straight line. 



9. Comparison q/Me Devonian Series ©/"Belgium awe? England. 

 By D. Sharpe, Esq., F.R.S., G.S. 



[This paper was withdrawn by the Author, with the permission of the Council.] 



