352 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 7, 



been pressed down at certainly two, if not more, distinct times ; at 

 the first projecting the sand further towards the west than the sub- 

 sequent force, which did not send the sand more than one half the 

 way over that first discharged ; so that the surface of the stone now 

 shows two terraces, — ^just what we might expect to see, if one portion 

 of a semi-fluid mass had been displaced, and then another portion 

 poured partly over it. 



The distances between the impressions, from the middle of one to 

 the middle of the next, measured 2 feet 10^ inches in every instance. 

 Nos. 2 and 3, those most resembling human footmarks, were each 

 1 3 inches in length at the bottom, and 1 7 inches at the top ; their 

 breadth being respectively 4 and 3^ inches at the bottom, and 8 and 

 9 inches at the top ; their depth being about 3 inches*. In these 

 two impressions, as before observed, the cast has not come clean 

 out of the mould, but left a little of it in ; so the depth is not easy 

 to obtain. The bottom of the impressions was concave, so far as 

 they can be seen ; and in two of them there were marks of something 

 resembling claws or nails visible. 



Nos. 1, 4, and 5 (the last of which is not figured, but resembled 

 exactly its neighbour. No. 4) were about the same size, and measured 

 6 by 8 inches at the bottom, and 10 by 12 inches at the top ; their 

 depths being about 5 inches each. The bottom parts of these im- 

 pressions are concave, and their casts have come cleaner out of the 

 moulds than the longer ones have done. 



No portion of the sandstone-rock (which is a coarse grit contain- 

 ing white quartz-pebbles, sometimes nearly an inch in diameter) nor 

 the beds of shale, either above or below it, afford any evidence what- 

 ever of sun-cracks. This is the case, so far as the writer has examined, 

 with the whole of the great Lancashire Coal-field, comprising arena- 

 ceous and argillaceous beds to the thickness of 6600 feet, although 

 he has met with numerous instances of such markings in the sand- 

 stone beds of the Trias at Lymm, and at Weston Point near Runcorn, 

 where the tracks of the Labyrinthodon and Rhynchosaurus are found. 

 The English Coal-measures up to the present time have not afforded 

 evidence of sun-cracks ; but Sir Charles Lyell has noticed them in 

 the Carboniferous strata of the United States at Greensburgt ; so it 

 is probable they will be ultimately met with in this country as well. 



How have the impressions above described been produced ? At 

 the time of their discovery it was safely concluded that they had been 

 made by some force acting upon the sandstone before it was consoK- 

 dated, and when it had existed in a soft or semi-fluid state ; and that 

 such force had in each case acted twice, so as to displace two portions 

 of wet sand at two different, but not long distant, periods. The 

 straight line of the track, and the regular distances between the 

 impressions led many persons to believe that they had been made by 



* The measurements are difficult to make correctly ; for the surface of the 

 matrix has evidently shrunk near the sides of the impressions, and some of the 

 wet sand gone into them. 



t Manual of Elementary Geology, 3rd edition, p. 337. 



