OF THE BASIN OF MINAS. 239 
their tracks found in the Connecticut River sandstone. 
There cannot be the slightest doubt that during the Trias- 
sic period the valley of the Connecticut, from New Haven 
to a point about one hundred and twenty miles north of 
that city, and with an average width of about twenty 
miles, formed an estuary, to which the sea had imperfect 
access, and that the sandstones and shales which now fill 
it, were therein deposited, under circumstances exceed- 
ingly like those under which the mud deposits are now 
accumulating in the northern estuaries of the Avon and 
Cornwallis, though there was there a slow submergence 
going on which gave an opportunity for the distribution of 
the tracks through hundreds of feet of beds, a thing which 
would otherwise have been impossible. In this estuary 
were extensive mud-flats and sand-banks covered by high 
tide, and left bare when the tide was out, and these were 
the resort of great numbers of animals whose footprints 
are alone preserved. The majority of these animals were 
reptiles, but others were probably birds. Huge fellows 
were some of them, making tracks about two feet in 
length. Yet, though these footprints are very abundantly 
handed down to us, the rocks themselves hold scarcely a 
vestige of animal remains. Besides a few fish, a shell or 
two, and an insect, only a few broken bones have been 
discovered thus far, and these last enable us to form only 
a suspicion as to the character of the animals to which 
they belonged. It would be very unlikely that the re- 
mains of land animals, which only frequented the shores 
between the tides, should be found in the deposits there 
forming, and we have already remarked how rare it is to 
find a dead bird on the Horton shores. 
Some of the shale-beds of the Connecticut valley resem- 
ble very closely, both in color, texture, and composition, 
