232 WALKS AND TALKS. 



There was a time in the very remote past, when tidal 

 action on the earth must have been vastly more efficient than 

 at present. I have already remarked that the moon, if .dis- 

 engaged from the earth, as we argue, was once near enough to 

 produce an enormous tidal effect. When the moon was but 

 forty thousand miles from the earth, its tidal efficiency was 

 two hundred and sixteen times as great as now. The oceanic 

 tide, accordingly, would have risen six hundred feet twice 

 during each revolution of the earth, with a similar subsidence 

 in the interval. We can hardly conceive the effects of such 

 an occurrence. Think of such a mountain of water rolling 

 in. Think of the collision with the beach; think of the in- 

 undation which would bury the beach and sweep inland ; 

 think of the terrific erosion which would ensue ; think of the 

 same flood tearing back into the sea to repeat its invasion in 

 a few hours. How rapidly the land must have disappeared ; 

 how coarse the fragments hurled into the sea, and how remote 

 their distribution. If these events occurred during the accu- 

 mulation of any sediments which in our age have become 

 rocks, what vast beds of coHglomerates must there be. Do 

 we find them in the series of Eozoic formations ? No. There 

 are conglomerates, but not more bulky or coarse than in most 

 of the later formations. The conjecture was expressed by 

 Professor R. S. Ball that such high tides had occurred during 

 Palaeozoic time ; but we find no evidence of it nor even of 

 their occurrence during Eozoic time. As they must have oc- 

 curred, however, we may place them in an seon earlier than 

 that which witnessed the laying down of any sediments which 

 have been preserved to human times. 



The end of the Eozoic JEon approached at last. Life had 

 appeared in the form of humble sea-weeds; and life had 

 throbbed into conscious being in the forms of the humble 

 Eozoon which I have before described. I can not admit that 

 no other forms of life found fitting home in the Eozoic sea; 

 but no demonstration of it has been discovered. We know, 

 however, that a vast thickness of rock-sediment was accumu- 

 lated, and that now very considerable areas were upraised to 



