TIME AND CHANGE 
be fifty thousand years or more since the great ice- 
sheet left us. Where protected by a thin coat of soil, 
its scratches and grooves upon the surface rock are 
about as fresh and distinct as you may see them 
made in Alaska at the present time. Where the 
rock is exposed, they have weathered out, one eighth 
of an inch probably having been worn away. The 
drifting of the withered leaves of autumn, or of the 
snows of winter over them, it really seems, would 
have done as much in that stretch of time. Then try 
to fancy the eternity it has taken the subaerial ele- 
ments to cut thousands of feet through this hard 
Catskill sandstone! No, the evolution of the land- 
scape, the evolution of the animal and vegetable 
kingdoms, the evolution of the suns and planets, 
involve a process so slow, and on such a scale, that 
it is quite unthinkable. How long it took evolution 
to bridge the chasm between the vertebrate and the 
invertebrate, between the fish and the frog, between 
the frog and the reptile, between the reptile and the 
mammal, or between the lowest mammal and the 
highest, who can guess? 
But the gulf has been passed, and here we are in 
this teeming world of life and beauty, with a terrible 
past behind us, but a brighter and brighter future 
before us. 
