James Neilson — Old Red and Carboniferous of Arran. 227 



It may be explained that these specimens were selected from their 

 resemblance (in all but colour) to a very remarkable and interesting 

 bed found in Maoldon, Arran, and that after the experiments the 

 specimens might very well have been mistaken for Arran ones. 



Note. — After the reading of the paper on October 17, 1895, the 

 Secretary of the Glasgow Geological Society was requested by 

 Sir A. Geikie to mention the fact that the statement as to the Arran 

 Limestone had already been corrected by him in his Annual Report 

 to the Science and Art Department for 1894, which was sent, soon 

 after publication, to the Mitchell Library, Glasgow, on Sept. 5, 1895. 



The author desires to add that he was entirely unaware that Sir 

 A. Geikie had published any statement on the subject, otherwise he 

 would have embodied it in his paper. He now adds the following 

 extract from Sir A. Geikie's Report referred to above : — 



" Permian (p. 284). — The age of the red sandstones which extend 

 along the shore from Corrie to Brodick and thence across the 

 southern half of the island, underneath the various sheets of 

 eruptive rocks, has been much discussed. 



" By Sedgwick and Murchison these strata were classed as New Red 

 Sandstone, a view which was subsequently adopted also by Ramsay. 

 Afterwards, however, Bryce and other writers placed them in the 

 Carboniferous system and correlated them with the red sandstones 

 of the north of Ayrshire and Renfrewshire. A re-examination of 

 the ground was made by me last spring, in company with Mr. 

 Peach and Mr. Gunn. We found that pebbles of the Carboniferous 

 Limestone and its characteristic fossils actually occur in the breccias 

 at the base of these red sandstones between Corrie and the north 

 end of Arran, as was first observed some years ago by Mr. James 

 Thomson. Closer inspection of the coast- sections and of the interior 

 showed us that, besides this evidence of a decided stratigraphical 

 break, the red sandstone, conglomerates, and breccias lie uncon- 

 formably on the Carboniferous formations, though at the actual 

 junctions the two series seem almost conformable. 



"It was thus manifest that these red sandstones could not be Lower 

 Carboniferous as was supposed, but must be later than the Car- 

 boniferous Limestone series. North of Corrie they rest on the 

 uppermost members of the Limestone series or the base of the 

 Millstone Grit. In the interior, at the head of Benlister Glen, they 

 lie on the Corrie Limestone hundreds of feet lower down in the 

 Carboniferous system, while on the west coast, at the mouth of the 

 Machrie Water, they appear to come directly down upon the Old 

 Red Sandstone, the whole of the Carboniferous formations having 

 there disappeared. These upper unconformable, and overlapping red 

 strata may be divided into two fairly well-marked sections — a lower 

 group consisting of massive false-bedded sandstones varying from 

 a bright brick-red colour to tints of yellow or grey ; and an upper 

 group of red marls, and shales, containing thin sandstones and oc- 

 casional thin seams of nodular limestone That they are probably 



Permian, may be inferred " 



