544 Mr. Scrope on the Ripple-Maries and 



municated by the resistance a, has exhausted itself. The 

 points 6, b, in the diagram, are those where the water impinges 

 on the bottom. The spaces between them, x, x, are compara- 

 tively at rest, and here, therefore, sand and drift arranges itself, 

 producing the ridges or ripple-mark observable on the bed of 

 a stream. 



The ripple-mark is not confined to the effects of water, but 

 is occasionally formed likewise by the wind on the surface of 

 loose sand, or of drifted snow. 



To return to the ripple-beds of forest marble. I had often 

 admired the sharpness and beauty of their wrinkles, appearing 

 as if freshly moulded by the receding tide, and carrying the ob- 

 server back at once to the moment when the sea broke upon the 

 then narrow shores of this infant island. I had often remarked 

 upon their surface sinuous traces, like the track of some animal 

 burrowing in the sand, but failed in satisfying myself to what 

 they were owing (fig. 1, pi. 5). Having, in the summer of 

 last year, visited the sandstone quarries of Corncockle Muir, in 

 Dumfriesshire, where several impressions of the footsteps of 

 tortoises have been found, it occurred to me to examine mi- 

 nutely the surfaces of these oolite beds, which, particularly 

 when rippled, are as smooth and fresh in appearance as when 

 first formed, and likely therefore to have retained any impres- 

 sions originally made upon them of similar foot-tracks. 



I had not long looked for such before I found a very great 

 abundance of tracks, certainly not of tortoises, but of some 

 much smaller animal, traversing the surface of the beds in every 

 direction ; and some specimens of these tracks, as well as of the 

 ripple-marks, were lately presented to the Geological Society, 

 (fig. 2, pi. 5). 



It is impossible, I think, to hesitate for one moment in be- 

 lieving them to be the foot-marks of some small and active 

 animal moving on the soft surface of the sand and mud imme- 

 diately after its deposition ; and it is difficult to suppose that 

 surface not to have been left dry at the time by the receding 

 tide, since so small an animal as this must have been, could 

 hardly have had sufficient weight to make such deep marks 

 below, or at any depth below the surface of the water ; nor is 

 it easy in that case to believe, that they would, if made, have 



