346 NEW BED SANDSTONE OF THE U. STATES. [Ch. XXII. 



glomerate are found occupying an area more than 150 miles in length 

 from north to south, and about 5 to 10 miles in breadth, the beds dipping 

 to the eastward at angles varying from 5 to 50 degrees. The extreme 

 inclination of 50 degrees is rare, and only observed in the neighborhood 

 of masses of trap which have been intruded into the red sandstone while 

 it was forming, or before the newer parts of the deposit bad been com- 

 pleted. Having examined this series of rocks in? many places, I feel 

 satisfied that they were formed in shallow water, and for the most part 

 near the shore, and that some of the beds were from time to time raised 

 above the level of the water, and laid dry, while a newer series, composed 

 of similar sediment, was forming. The red flags of thin-bedded sandstone 

 are often ripple-marked, and exhibit on their under sides casts of cracks 

 formed in the underlying red and green shales. These last must have 

 shrunk by drying before the sand was spread over them. On some 

 shales of the finest texture impressions of rain-drops may be seen, and 

 casts of them in the incumbent argillaceous sandstones. Having observed 

 similar markings produced by showers, of which the precise date was 

 known, on the recent red mud of the Bay of Fundy, and casts in relief 

 of the same, on layers of dried mud thrown down by subsequent tides,* 

 I feel no doubt in regard to the origin of some of the ancient Connecticut 

 impressions. I have also seen on the mud-flats of the Bay of Fundy the 

 footmarks of birds (Tringa minuta), which daily run along the borders 

 of that estuary at low water, and which I have described in my Travels.f 

 Similar layers of red mud, now hardened and compressed into shale, are 

 laid open on the banks of the Connecticut, and retain faithfully the im- 

 pressions and casts of the feet of numerous birds and reptiles which 

 walked over them at the time when they were deposited, probably in the 

 Triassic Period. 



According to Prof. Hitchcock, the footprints of no less than thirty-two 

 species of bipeds, and twelve of quadrupeds, have been already detected 

 in these rocks. Thirty of these are believed to be those of birds, four of 

 lizards, two of chelonians, and six of batrachians. The tracks have been 

 found in more than twenty places, scattered through an extent of nearly 

 80 miles from north to south, and they are repeated through a succession 

 of beds attaining at some points a thickness of more than 1000 feet, 

 which may have been thousands of years in forming. J 



As considerable skepticism is naturally entertained in regard to the 

 nature of the evidence derived from footprints, it may be well to enume- 

 rate some facts respecting them on which the faith of the geologist may 

 rest. When I visited the United States in 1842, more than 2000 im- 

 pressions had been observed by Professor Hitchcock,§ in the district 

 alluded to, and all of them were indented on the upper surface of the 

 layers while the corresponding casts, standing out in relief, were always 



* Principles of GeoL 9th ed. p. 203. 



\ Travels in North America, vol. iL p. 168. 



X Hitchcock, Mem. of Amer. Acad. New Ser. vol. iii. p. 129. 



§ See also Mem. Amer. Ac. voL iii. 1848. 



