1856.] HARKNESS — PERMIAN ROCKS OF SCOTLAIND. 265 



the nature of these smgular markings ; some of the most beautiful 

 having been sent to him and being now in his possession. They are 

 a unique form of desiccation-cracks, produced on mud which, in con- 

 sequence of exposure to solar rays after the cracking, has curled up 

 at the edges in some instances ; and this curling has sometimes pro- 

 ceeded so far as to cause the mud to assume almost the form of a 

 hollow cylinder, into which the sand has been afterwards poured ; 

 and in consequence we have the stem-like forms which occur in these 

 sandstones. Sir W. Jardine informs me that he has seen modifica- 

 tions of the same circumstances which produced these singular 

 markings take place on the banks of the River Annan among the 

 muds which have been deposited during freshets. 



These markings are not the only impressions which the sandstones 

 of the Maiden-Bower afPord. We frequently find on the upper sur- 

 faces of the strata pitted hollows ; and we have natural casts of these 

 on the under side of the overlying beds. On an average, the length 

 of these impressions is about ^ of an inch, and their breadth about 

 j^ of an inch, so that they have a form approaching to oval. They 

 have a deeper impression on one end than the other, which gradually 

 thins out ; and these deeper impressions are all in the same direction 

 on one surface. I was at first inclined to regard them as resulting 

 from rain-drops ; but they are larger and more irregular than the 

 pittings produced by either rain or hail ; and Sir Charles Lyell, who 

 had an opportunity of examining this quarry with me, suggested that 

 they might be caused by the splashing of spray driven almost hori- 

 zontally on a muddy shore. Their elongated form shows that the 

 force causing them had a less perpendicular direction than rain, and 

 spray driven by the vdnd from the sea appears to have been their 

 origin * . 



If the singular markings already alluded to be the result of desic- 

 cation, and if these irregular oval markings owe their occurrence to 

 spray, then we have on these ancient shores proofs of a hot sun's 

 rays falling on a muddy beach, and proofs of the lashings of the sea 

 by a violent wind which drove the tops of the foam- crested waves in 

 the form of spray on this old beach. 



Isolation of the Sandstone-areas. — The isolated position of the 

 several sandstone-areas is a subject which next presents itself. Look- 

 ing at these patches on the map, and knowing that some of them are 

 surrounded by lofty mountains, it will at once be perceived that they 

 could not have been deposited singly in the several areas which they 

 occupy. 



The intimate connexion which exists in the lithological characters 

 of the series of beds forming these patches, shows that they have had 

 a much more intimate union than they now possess ; and all the 

 circumstances lead to the inference that they are the relics of a large 

 mass of sandstones and breccias which at one time covered a great 

 portion of the South of Scotland ; and which has been to a very great 

 extent removed from the surface of the upturned Silurians by denuda- 



* Original sketches of these markings and of the desiccation-cracks are deposited 

 in the Society's Library. — Ed. 



