124 GEOLOGY OF ARRAN. 



thickness, and these by thick-bedded gray sandstone and 

 nodular limestone, till we reach the representatives of the 

 Corrie limestones, near the Salt Pans, prolific of the same 

 fossils. Lagantuin Bay, towards the lower portion of the 

 series, exhibits a great body of intrusive trap, in a position 

 almost at the base of the series, and thus exactly correspond- 

 ing to that already noticed a short distance N. of Corrie; 

 the two outflows being very nearly at equal distances from 

 the base of the carboniferous series. These eruptive rocks 

 consist of diorite of porphyritic structure (trap porphyry), 

 containing crystals of diallage, amygdaloid with zeolites, 

 steatite and carbonate of lime, trap tufa and claystones; 

 they upturn the shales to 58 from their usual inclina- 

 tion of 20. Beyond and overlying these, as we advance 

 along the shore, there are various thick-bedded sandstones 

 with black and red shales, and beds of trap tufa; these 

 subside under the debris, and there is a considerable space 

 where no rock is seen till we reach Millstone Point, where 

 we again come upon thick white sandstones and gray 

 shales, dipping N. 5 E. at 39. A little W. of this, 

 near the gamekeeper's cottage, we come upon one of the 

 most interesting spots upon this whole coast. Here, during 

 the autumn of 1865, Mr. Edward A. Wiinsch, Glasgow, 

 discovered that certain dark-coloured beds in the sandstone, 

 which had been only casually noticed by all previous 

 observers, and set down as sheets and dikes of trap, are 

 really hardened shales and beds of trappean ash, and con- 

 tained stems and branches of trees. A history of the 

 discovery and account of the beds, with a diagram, from 

 which our cut is taken, was published in the Transactions 

 oftfie Geological Society of Glasgow, vol. ii. p. 97 (November 

 1865). The beds were also carefully examined by Mr. 

 John Young of the Hunterian Museum, and Mr. James 

 Russell, coal surveyor, Chapelhall, whose zeal and great saga- 

 city as observers are known to all geologists; they were re- 

 examined by Mr. Wiinsch and ourselves in the following 



