TIME AND CHANGE 
ing Paleozoic 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 Jand-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 
