James Neilson — Old Red and Carboniferous of Arran. 155 



especially in the parish of Rowington. They are exposed on the 

 banks of the canal and along the road leading to Warwick, and were 

 formerly obtained from quarries in the parish now long ago filled 

 up, according to certain old documents in our parish chest, which 

 gives an account of payments made for stone from this place, and 

 our fine church and others in the neighbourhood and some old 

 houses are built of it. When the Great Western Railway was made 

 here a deep cutting through the sandstones was exposed along the 

 line at Finwood in this parish ; and lately they were detected 

 when the new line to Henley was constructed. All the higher 

 ridges in this district — they can hardly be called hills — are com- 

 posed of the sandstones, the lower gi'ound, where the marls 

 and sandstones have been denuded, being formed of the red 

 marls below. Sections are generally rare, as the stone is seldom 

 employed except at Shrewley quarry near here, where the best 

 section of the Upper Keuper beds are exposed. There are about 

 two beds of useful stone : the upper one is inferior to the lower 

 or bottom rock, which is a hai'd sandstone of some thickness 

 and makes a good building stone, and is used by the Canal Company. 

 This quarry is famous for many interesting fossils so scarce in the 

 Trias, and is noted for the remains of fish, viz., Semionotus, Acrodus 

 (spines and teeth), footprints of Labyrinthodon, and, the rarest of 

 all, moulds of several species of mollusks, the only British locality 

 where any shells have been found. I may add that the wells in the 

 parish are fairly supplied with water from the sandstones, but it is 

 hard and more or less charged with sulphates. 



Note. — All the type and unique 1 specimens lately in my collection 

 from the Warwickshire Trias, especially Shrewley and Coten End, 

 are now in the British Museum (Natural History), South Kensington. 



IV. — On the Old Red Sandstone and Carboniferous Rocks op 

 the North-east of the Island of Arran. 1 



By James Neilson, 

 Vice-President of the Glasgow Geological Society. 



IN the third edition of his Text-Book of Geology, Sir Archibald 

 Geikie has discussed the question whether fossils can be 

 wholly depended upon to indicate the age of rocks when similar 

 or representative species are found in areas wide apart. Thus 

 he tells us (p. 665) that in Bohemia and Russia some of the 

 most characteristic Upper Silurian organisms are found beneath 

 strata replete with Lower Silurian life. Again, speaking of the 

 close of the Silurian period, he says (p. 760) : " There is every 

 reason to believe that for a long time the marine sedimentation 

 of Upper Silurian type continued to prevail in some areas, while 

 the probably lacustrine type of the Old Red Sandstone had 

 already been established in others." He also tells us (p. 828) 

 that " In the West of Scotland there occur among the red sand- 

 stones (some of which contain Old Red Sandstone fishes) bands 

 1 Read before the Glasgow Geological Society on 17th October, 1895. 



