26 THE STORY OP THE EARTH AND MAN. 



To an observer in tlie Laurentian period, tlie earth 

 would have presented an almost boundless ocean, its 

 waters, perhaps, still warmed with the internal heat, 

 and sending up copious exhalations to be condensed in 

 thick clouds and precipitated in rain. Here and there 

 might be seen chains of rocky islands, many of them 

 volcanic, or ranges of bleak hills, perhaps clothed with 

 vegetation the forms of which are unknown to us. In 

 the bottom of the sea, while sand and mud and gravel 

 were being deposited in successive layers in some 

 portions of the ocean floor, in others great reefs of 

 Eozoon were growing up in the manner of reefs of coral. 

 If we can imagine the modern Pacific, with its volcanic 

 islands and reefs of coral, to be deprived of all other 

 forms of life, we should have a somewhat accurate 

 picture of the Eozoic time as it appears to us now. 

 I say as it appears to us now ; for we do not know 

 what new discoveries remain to be made. More 

 especially the immense deposits of carbon and iron in 

 the Laurentian would seem to bespeak a profusion of 

 plant life in the sea or on the land, or both, second to 

 that of no other period that succeeded, except that 

 of the great coal formation. Perhaps no remnant of 

 this primitive vegetation exists retaining its form or 

 structure; but we may hope for better things, and 



however, so far as stated publicly, have been shown to depend 

 on misapprehension as to the structures observed and their 

 state of preservation; and specimens recently found in com- 

 paratively unaltered rocks have indicated the true character of 

 those moi ^ altered by metamorphism. 



