160 James Neilson — Old Red and Carboniferous of Arran. 



but, as these beds are not represented on the southern part of the 

 district, I propose to defer their consideration till I take up the 

 others. 



To return now to the consideration of the similar beds at the 

 southern portion of the section, viz. at the 320 yards broad dike, 

 whose southern edge terminates on the shore, opposite the school 

 grounds at Corrie. As already stated, this dike marks a great fault. 

 I am rather surprised that it should not have heen recorded before, as 

 the evidence seems clear enough. The cornstones occur immediately 

 to the north of it, while the marine limestones are only a few 

 hundred yards south; so that this fault cuts off all the strata 

 represented, along about two miles of shore on the northern section, 

 i.e. from the cornstones north of the fallen rocks to the shepherd's 

 house at Laggan, i.e. nearly all the Calciferous Sandstone series : 

 a displacement which may be roughly estimated at ahout 300 fathoms. 



The beds known as the Corrie Limestone consist of twenty-two 

 beds of limestone, interstratified with beds of red shale ; the total 

 thickness of limestone being about twentj r feet. These beds are 

 referred to by Sir A. Geikie as follows (p. 801): "A band of 

 marine limestone, lj'ing in the red sandstone series in Arran, is 

 crowded with ordinary Carboniferous Limestone shells, such as 

 Productus giganteus, P. semireticulatns, P. punctahis, Chonetes hard- 

 rensis, Spirifer lineatus, etc." 



The latter part of this quotation I very heartily endorse. The 

 strata, consisting of sandstones, shales, etc., are mostly red. Even the 

 limestone fossils are as red as the sandstones themselves. They are 

 crowded with fossils; Productus giganteus exists here by the million. 

 Owing to a great upthrow these same limestones appear on the 

 northern flank of the hill called Maoldon. 



Three other upthrows of the same limestone occur further to the 

 south, but it is unnecessary here to refer to them. There can lie 

 no doubt that these are the same limestones, previously observed on 

 the north shore, near the shepherd's house at Laggan. Generally 

 speaking, the fossils are the same, as is also the character of the 

 limestone and interbedded shale, in all but the colour. 



There can be no question that the red colour is due to the presence 

 of hematite iron-ore distributed through the strata, and many seams 

 hold this mineral to such an extent as to soil the hands — which some 

 of the fossils will do even after years of exposure to the weather. 

 These ores also appear sometimes as seams of red ironstone, and at 

 other times the ironstone is segregated into detached nodules or into 

 nodular bands. Good examples of both kinds are to be seen in the 

 old quames, on the hills behind the village, and also on the shore at 

 Corrie ; but, although the prevailing colour is red, this is not by 

 any means universal, and white sandstones are, and have been, 

 quarried behind the village of Corrie, both above and below the 

 limestones— e.g. in a quarry behind Corrie Hotel, where a white 

 sandstone may be seen overlain by a bed of fireclay, containing 

 the usual Stigmarian rootlets. 



As has already been shown, the same limestone and shales and 



