﻿NO. I 



SMITHSONIAN EXPLORATIONS, I925 



21 



The great antiquity of these footprints is clearly demonstrated 

 at this locahty, for it is evident that since the day when those ani- 

 mals impressed their feet in what at that time was moist sand, more 

 than 1,000 feet of rock-making materials were piled up in successive 



l^iG. 25. — Slab of fossil footprints in situ on the 

 Hermit Trail, Grand Canyon National Park. 

 (Photograph by Gilmore.) 



strata above them and this does not take into account many hundreds 

 of feet more that have been eroded off the present top of the canyon 

 wall. 



The great length of time necessary for the cutting away or erosion 

 of the rock to form the deep canyon and the even longer time 

 necessary for the original deposition of this great vertical mass of 



