﻿lx PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



enters into all the flexures of the Appalachian chain, whereas the red 

 sandstone of the Connecticut, or at least its equivalent in New Jersey, 

 reposes in many places unconformahly on the denuded edges of the 

 inclined or vertical Appalachian beds. 



When I first examined these strata of shale and sandstone near 

 Jersey city, in company with Mr. Redfield, I saw at once from the 

 ripple-marked surface of the slabs, from the casts of cracks, the marks 

 of rain-drops, and the imbedded fragments of drift-wood, that these 

 beds had been formed precisely under circumstances most favourable 

 for the reception of impressions of the feet of animals, walking be- 

 tween high and low water. In the prolongation of the same beds in 

 the valley of the Connecticut, there have been found, according to 

 Professor Hitchcock, the foot-prints of no less than thirty-two species 

 of bipeds and twelve of quadrupeds. Thirty of these are referred to 

 birds, four to lizards, two are believed to be those of chelonians, and 

 six to be batrachians, the remaining two being doubtful. They have 

 been observed in more than twenty localities, which are scattered over 

 an area of nearly eighty miles from north to south in the states of 

 Massachusetts and Connecticut. After visiting several of these places, 

 I entertained no doubt that the sand and mud were deposited on an 

 area which was slowly subsiding all the while, so that at some points 

 a thickness of more than 1000 feet of superimposed strata had accu- 

 mulated in very shallow water, the foot-prints being repeated at various 

 intervals on the surface of the mud throughout the entire series of 

 superimposed beds. When I first examined this region in 1842, 

 Professor Hitchcock had already seen 2000 impressions, each of them 

 indented on the upper sides of layers of shale, while the casts of the 

 same, standing out in relief, always protruded from the lower surface 

 of the incumbent strata. Had they been concretions, as some geolo- 

 gists at first contended, they would have been occasionally found 

 projecting from the upper sides of strata of sandstone. I was also 

 much struck when following each single line of foot-marks, to find 

 how uniform they were in size and how nearly equidistant from each 

 other, whereas on turning to a larger or smaller set of impressions, 

 the distance separating any two tracts in the same series immediately 

 increased or diminished, there being an obvious proportion between 

 the length of the stride and the dimensions of the creature which 

 walked over the mud. There are also a great number of examples 



