140 SioKOL' City Academy of Science mid Letters. 



solving by the aid of carbonic acid held in solution, the 

 rocks upon which it has fallen, and by its currents carry- 

 ing the fine material to the ocean or lake, where it was 

 laid down as sediment beneath the waters. The first 

 crust that was formed on our globe oyer the molten mass 

 of planetary material must have been entirely devoid of 

 life of any kind and unable to sustain it if any chance had 

 cast it upon the shore. The earth must have slowly radi- 

 ated its heat away into space for unknown time, until it 

 was sufficiently cooled so that the waters, before held in 

 the air as a thick vaporous mass of clouds, preventing 

 the faintest passage of the light of the sun, could have 

 been condensed and precipitated to the surface in rain- 

 storms more violent than any we now have knowledge 

 of. Such water, at that time, must have been thick and 

 heavy with the minerals held in solution that were vol- 

 atilized by the great heat. At first the vaporous mois- 

 ture would be condensed in the colder currents of air 

 above the earth and falling towards the surface, would 

 at once be again changed to vapor by the heated rocks 

 and again rise to the air above and only after a long time 

 would it have reached the surface. Thus there must 

 have been a continual change of water, thick with car- 

 bonic acid, lime and other minerals, falling to the earth 

 and rising again as vapor. Such action of acidulated 

 water would have disintegrated and broken down the 

 heated rocks very much faster than is now being done. 

 This erosive action would have carried its fine sediment 

 to the low places on the surface, and this, acting as a pro- 

 tecting cover, would have confined the heat and allowed 

 the water to gather there in the depressions, thus mark- 

 ing out the future oceans and continents. With the ever 

 increasing weight of water and sediment, the then thin 

 crust must have continually sunk lower, while the dry 

 land would as naturally have been more and more ele- 

 vated, and the erosion from the falling rain thus in- 

 creased. 



Oscillation of the surface must, in those young years 

 of the earth, have been much greater than now, chang- 

 ing land surface to sea and elevating the sea bottom 

 above the waters. Most geologists, however, believe that 



