THE DAWN OF LIFE IO3 



Some subsequent writers have, it is true, treated with dis- 

 belief Logan's great discoveries ; but no competent geologist 

 who has traced the regularly bedded limestones and other 

 rocks of his original fields of investigation could continue to 

 doubt. On this subject I may quote from my friend Dr. 

 Bonney, one of the most judicious of the builders who under- 

 take hypothetically to lay the foundation stones of the earth's 



FIG. 3. The Laurentian Nucleus of the American Continent, after Dana. 



crust for our enlightenment in these later days. In an address 

 delivered at the Bath meeting of the British Association he 

 says : 



" The first deposits on the solidified crust of the earth would 

 obviously be igneous. As water condensed from the atmo- 

 sphere on the cooling surface, aqueous waste or condensation 

 would begin, and stratified deposits in the ocean would become 



