FOSSIL FOOTSTEPS. 199 



The same causes, which have so commonly preserved 

 these undulations, would equally preserve any impressions 

 that might happen to have been made on beds of sand, by 

 the feet of animals ; the only essential condition of such pre- 

 servation being, that they should have become covered with 

 a farther deposite of earthy matter, before they were obli- 

 terated by any succeeding agitations of the water. 



The nature of the impressions in Dumfries-shire may be 

 seen by reference to PI. 26. They traverse the rock in a 

 direction either up or down, and not across the surfaces of 

 the strata, which arc now inclined at an angle of 38°. On 

 one slab there are twenty-four continuous impressions of 

 feet, forming a regular track, with six distinct repetitions 

 of the mark of each foot, the fore-foot being differently 

 shaped from the hind-foot; the marks of claws are also very 

 distinct.* 



found rippled markings, and abundant foot tracks of small animals on the 

 Forest marble beds north of Halii. These were probably tracks of Crusta- 

 cea.— See Phil. Mag. May, 1831, p. 376. 



We find on tiie surface of slabs both of the calcareous grit, and Stonesfield 

 slate, near Oxford, and on sandstones of the Wealden formation, in Sussex 

 and Dorsetshire, perfectly preserved and petrified castings of marine worms, 

 at the upper extremity of holes bored by them in the sand, while it waa 

 yet soft at the bottom of the water; and within the sandstones, traces of 

 tubular holes in which the worms resided. The p^e^^ervation of these tubes 

 and castings shows the very quiet condition of the bottom, and the gentle 

 action of the water, which brought the materials that covered them over, 

 without disturbing them. 



Cases of this kind add to the probability of the preservation of footsteps of 

 Tortoises on the Red sandstone, and also afford proof of the alternation of 

 intervals of repose with periods of violence, during the destructive processes 

 by which derivative strata were formed. 



* On comparing some of these impressions with tiie tracks which I 

 caused to be made on soft sand, and clay, and upon unbaked pie-crust, by a 

 living Emys and Testudo Grjecn, I found the correspondence with the latter 

 sufficiently close, allowing for difference of species, to render it highly pro- 

 bable that the fossil footsteps were also impressed by the feet of land 

 Tortoises. 



In the bed of the Sapey and Whelpley brooks near Tcnbury, circulai 



