1887.] NEW YOKK ACADEMY OF SCIENCES. 125 



and sand^ now sandstone and shale. The inflow and oulflow of 

 thewater, and its brackish character, were unfavorable to the de- 

 velopment of animal or vegetable life, and as a consequence we 

 find the Triassic strata remarkably barren of fossil remains. Tliis 

 absence of organic matter, and the exposure of the sediments to 

 the air, resulted in the peroxidation of the iron they contain, 

 and therefore the prevailing color of both sandstones and shales 

 is red or reddish brown. 



By the ebb and flow of high tides the shores of these estuaries 

 were alternately laid bare and again covered by a sheet of sedi- 

 ment carried by an oveiflow of the water. The shores thus 

 alternately covered and exposed seem to have been the feeding 

 grounds of a host of terrestrial, air-breathing animals which 

 have left their tracks in great numbers on many layers in the 

 series. About one hundred different kinds of tracks have been 

 distinguished, varying in size from one inch to nearly two feet 

 in length. Most of the impressions are those made by three- 

 toed bipeds and closely resemble the tracks of birds; but some of 

 them are four and even five toed. They are now generally re- 

 garded as the tracks of reptiles and amphibians, which inhabited 

 this region in great numbers, but left almost no other record of 

 their existence than these autographs. A few bones and portions 

 of two skeletons are all the remains yet found of the animals 

 themselves. 



Alternating with the barren red sandstones and shales of the 

 Triassic series, are some layers of dove-colored shale which con- 

 tain much diffused organic matter, a few impressions of plants, 

 and large numbers of the remains of fishes. The plants are 

 cycads, conifers and ferns, mostly of the same species with those 

 found in the coal basins of Virginia and North Carolina and 

 described by Prof. Fontaine in a monograph on "Tiie Older 

 Mesozoic Flora of Virginia,'^ published by the U. S. Geological 

 Survey. These plant remains are generally fragmentary and are 

 evidently twigs and leaves, representing the vegetation which 

 covered the shores of the estuaries. No broad-leaved,plants (angio- 

 sperms) grew here or anywhere on the eartli in the Triassic age, 

 but the forests which covered the uplands consisted of sago- 

 palms and conifers; some of the latter resembled Juniperus, 



