THE TOOTH OF TIME. 347 



of formations, and sunken a thousand feet into the solid 

 granite. The section of the rocks in the gorge shows 

 above the granite two or three thousand feet of paleozoic 

 sandstones, shales, and limestones, one thousand feet of sub- 

 carboniferous limestones, and twelve hundred feet of car- 

 boniferous sandstone and limestone. Higher up the stream 

 the section extends up through the Triassic and Cretaceous 

 systems. 



What aeons have rolled by while this unparalleled river- 

 work has been in progress ! And yet this work must have 

 been limited to the later ages, since the gorge cuts through 

 Cretaceous strata. There was a time, during the Cenozoic 

 ages, before yet the ridges of the Rocky Mountains had 

 been elevated to their present altitudes, when this vast 

 desert had just become dry land — upheaved from the re- 

 cent bottom of the Cretaceous sea. Now the Colorado be- 

 gan to gather its forces and to irrigate the surface of the 

 new-formed land. ISTow began the great canon ; but for 

 many ages the surface features of the region were normal ; 

 and not improbably it was clothed with a soil, and watered 

 by streams which sustained a luxuriant growth of vegeta- 

 tion. But man was slumbering in the voiceless future, and 

 lazy reptiles held possession of the fair domain. Vast, then, 

 as is the work, and vast as must have been its duration, its 

 commencement can date back but to the end, or, at farthest, 

 to the beginning of Cenozoic Time. 



Who can tell but similar gorges have been cut in the 

 strata of more eastern states. Here was land — permanent 

 land — covered with vegetation, while yet the great desert 

 was but ocean-slime. Here, too, were rivers — rivers like 

 the Ohio and the Mississippi — with their numerous tribu- 

 taries. What prevented these streams from scoring the 

 strata to the depth of ten thousand feet ? We know that 

 during this interval the Niagara cut an ancient gorge. We 



