James Neilson — Old Red and Carboniferous of Arran. 159 



in the section than the preceding bed, and as the strata dip at angles 

 of from 20° to 70°, a mile along the shore represents a considerable 

 thickness of strata. From this point onwards for a distance of about 

 three miles the red colour of the rocks is very exceptional indeed, and 

 not until one passes the Salt Pans does he come again to the pre- 

 dominating red rock, and then, as will afterwards be shown, at a 

 horizon several thousand feet higher up in the geological scale. 



Succeeding and overlying the fish-beds is a great thickness of 

 white calciferous sandstones, till at Millstone Point, about one mile 

 north of the fallen rocks, black shales are met with full of plant- 

 remains in the condition of anthracite. The observer next reaches 

 the sections of trap and ash beds, interbedded with shales and thin 

 seams of coal, among which the late Mr. E. A. Wiinsch made his 

 interesting discovery of a forest entombed in volcanic ash, yet in 

 such a way as to preserve the minute structure of the plants. 1 

 Mr. Wunsch recorded the disinterment of fourteen large tree stems, 

 and some more were dug out during the meeting of the British 

 Association in Glasgow in September 1876. 



Dr. Bryce (p. 127) also records the finding of a palatal tooth of 

 Ctenodus crista tus — surely a Carboniferous fish. The plants recorded 

 from this bed are : Sigillaria, Halonia, Lepidodendron, Lepidostrobus 

 (3 species), Antholithes, Sphenopteris, Stigmaria, and Strobilites. 

 Mr. Wunsch estimated the thickness of the igneous rocks, with inter- 

 bedded shales, etc., at about 1000 feet, and between these and the 

 Old Red Conglomerate there will be, I should think, at least as 

 much more. 



The limestones (which are reached after passing some white or 

 grey sandstones) follow next in succession, so that there are here some 

 2000 feet of strata underlying the fossiliferous limestone. I do not 

 hesitate to assign these strata to the Calciferous Sandstone series, and 

 the great thickness of the igneous rocks among which Mr. Wunsch's 

 discovery was made, to the great outburst of Trap which extends 

 over Scotland, and has given origin to the Trap hills of South Bute, 

 Little Cumbrae, North Ayrshire, Kilpatrick, Campsie, Fifeshire, and 

 the Lothians. 



The fossiliferous limestone which occurs about 100 yards north- 

 west of the shepherd's house at Laggan is undoubtedly the same as 

 that at Corrie, and contains the same fossils, the prevailing one 

 being Productus giganteus, which is extraordinarily abundant. The 

 peculiarity about these is that the shales are black, while at Corrie 

 they are red, thus showing that the red colour is merely a local 

 phenomenon, even in Arran. 



These limestones are succeeded by white and grey sandstones and 

 black shales alternating. Some of the shales are charged with the 

 usual marine Carboniferous fossils, and extend along the shore to 

 Salt Pans, where they are succeeded by beds of a different character; 



1 Trans. Geol. Soc. Glasgow, vol. ii, p. 97. For descriptions of new species 

 from this deposit, see Mon. Palseont. Soc. 1870 ; Geol. Mag. 1865, p. 474 ; 

 ibid. 1867, p. 551. 



