THE ORIGIN OF LIFE 265 



possible that many silicious rocks of the Laurcntian 

 and Primordial ages, which now show no trace of 

 organization, may be indirectly products of the 

 action of life. In any case it seems plain that beds 

 of greensand and similar hydrous silicates may be 

 the residue of thick deposits of foraminiferal lime- 

 stone or chalky matter, and that these silicates may 

 in their turn be oxidized and decomposed, leaving 

 beds of apparently inorganic clay. Such beds may 

 finally be consolidated and rendered crystalline by 

 metamorphism, and thus a great variety of silicated 

 rocks may result, retaining little or no indication of 

 any connection with the agency of life. We can 

 scarcely yet conjecture the amount of light which 

 these new facts may eventually throw on the ser- 

 pentine and other rocks of the Eozoic age. In the 

 meantime they open up a noble field to chemists and 

 microscopists. 



When the marvellous results of recent deep-sea 

 dredgings were first made known, and it was found 

 that chalky foraminiferal earth is yet accumulating 

 in the Atlantic, with sponges and sea-urchins re- 

 sembling in many respects those whose remains 

 exist in the chalk, the fact was expressed by the 

 statement that we still live in the chalk period. 



