26 On a remarkable Stratum of Limestone, [Ja^. 



the perforated stratum having assumed their present form, they 

 had been detached into distinct crystals by some process similar 

 to what basaltic columns owe their origin to, part of the mystery 

 might beconsidined as unriddled; for no accidental rocks could 

 have separated the stratum into these distinct blocks ; but still 

 the blocKs becoming each of them thinner towards their centre 

 is to be explained. Could a stream of water percolating through 

 the interstices have reduced them to this shape ? I rather fear 

 that the laws of hydraulics forbid such a supposition. The 

 middle part only of each block is worn away ; both ends remain 

 entire. Must we not, therefore, conclude that some extraordi- 

 nary operation depending on chemical laws has at once formed 

 each separate block into its present form ? but here I must call 

 to recollection the inadequacy of such speculations to explain 

 the subject of the present paper, and confine myself to a relation 

 of facts. 



Many years ago I had an opportunity of viewing from a short 

 distance an appearance which, if my memory does not fail me, 

 bore a considerable resemblance to the perforated stratum of 

 Calder Side. It was what seemed to be a range of holes resem- 

 bling in form the holes made by the Sand Martin (Hirundo 

 Riparia) in banks of sand, in which these birds construct their 

 nests. The holes which I allude to were situated in the front 

 of a steep rock overhanging the river Sotha, near the celebrated 

 falls of Trollhatta. It was in passing down the river in the dusk 

 of the evening that I saw them, so that I could not observe 

 whether the rock was stratified or not; and indeed I should 

 probably not at all have remarked them had not the boatman 

 who conveyed me down the river pointed them out to me, 

 remarking at the same time that they were the residence of 

 spirits ; and that during the fine nights in autumn, a bright 

 light was seen to issue from them. Most probably our ances- 

 tors would at once have referred the perforated stratum of Calder 

 Side to the times when various places in Scotland were peopled 

 by the fairies of popular superstition, and dated its origin at the 

 hands of supernatural beings, and explained its uses as forming 

 the abode of the spirits of the wood, or of the flood. 



Fig. 1 , is a section of the strata at Calder Side. 



Fig. 2, two of the blocks composing the perforated stratum 

 of limestone, taken from their place, and seen in perspective as 

 placed upon a wall near the spot. These blocks consist of what 

 may be termed an argillaceous limestone of a bluish grey colour, 

 apd of a very slaty texture. It appears to contain much 

 bitumen. 



