40 ANIMALS OF THE PAST 



being a blank. A few examples have, it is 

 true, been found, but these are only a tithe of 

 those known to have existed ; while of the great 

 animals that strode along the shore, leaving 

 tracks fifteen inches long and a yard apart 

 pressed deeply into the hard sand, not a bone 

 remains. The probability is that the strata 

 containing their bones lie out to sea, whither 

 their bodies were carried by tides and currents, 

 and that we may never see more than the few 

 fragments that were scattered along the sea- 

 side. 



That part of the A^alley of the Connecticut 

 wherein the footprints are found seems to have 

 been a long, narrow estuary running south- 

 ward from Turner's Falls, INIass., where the 

 tracks are most abundant and most clear. 

 The topography was such that this estuary 

 was subject to sudden and great fluctuations of 

 the water-level, large tracts of shore being now 

 left dry to bake in the sun, and again covered 

 by turbid water which deposited on the bot- 

 tom a layer of mud. Over and over again this 

 happened, forming layer upon layer of what is 

 now stone, sometimes the lapse of time be- 



