TIME AND CHANGE 



ing Palseozoic times would have favored more rapid 

 carbonation. When granite is dissolved by weather- 

 ing, carbon unites with the potash, the soda, the 

 lime, the magnesia, and the iron, and turns them 

 into carbonates and swells their bulk. The one thing 

 that is passed along from formation to formation un- 

 changed is the quartz sand. Quartz is tough, and the 

 sand we find to-day is practically the same that was 

 dissolved out of the first crystalline rocks. 



Take out of the soil and out of the rocks all that 

 they owe to the air, — the oxygen and the carbon, 

 — and how would they dwindle ! The limestone 

 rocks would practically disappear. 



Probably not less that one fourth of all the sedi- 

 mentary rocks are limestone, which is of animal 

 origin. How much of the lime of which these rocks 

 were built was leached out of the land-areas, and 

 how much was held in solution by the original sea- 

 water, is of course a question. But all the carbon 

 they hold came out of the air. The waters of the 

 primordial ocean were probably highly charged with 

 mineral matter, with various chlorides and sulphates 

 and carbonates, such as the sulphate of soda, the 

 sulphate of lime, the sulphate of magnesia, the 

 chloride of sodium, and the like. The chloride of 

 sodium, or salt, remains, while most of the other 

 compounds have been precipitated through the 

 agency of minute forms of life, and now form parts 

 of the soil and of the stratified rocks beneath it. 



108 



