46 The Phosphates of America. 



certa n characteristic differences in their essential features arising- 

 from the fact that one portion of them was deposited by fresh and 

 another by salt water. The oldest of them comprise gradually 

 ascending beds of sands, clays, compact sandstones, loose shell-beds 

 and calcareous sandstones, and they gradually develop into marls, 

 clays, chalk, solid limestones and greensands. No other age was 

 subjected at various intervals to more severe eruptive action, and 

 its close was marked by immense disturbances, of which most of 

 our active volcanoes remain as monuments for our wondering con- 

 templation. 



The portion of the tertiary strata in which our workable phos- 

 phate deposits are found may be broadly said to hug the coast of 

 the Atlantic Ocean and the Gulf of Mexico from New Jersey to 

 Texas, and to embrace within its area the most extensive marl-beds 

 in the world. 



Deposits of more or less commercial value and importance have 

 been located and worked in Virginia, North and South Carolina, 

 Alabama, Georgia and Florida, and there is no reason why they 

 should not be found in large quantities in States where they are not 

 at present known, or where they have only hitherto appeared to be 

 of very low grade. 



If no further discoveries should take place in our time, however, 

 the vast beds of South Carolina and Florida are capable of yielding 

 more than sufficient to supply the entire needs of the world far into 

 the future, and as they are the only present sources likely to be 

 extensively exploited in this country, we may dismiss all others 

 without further comment. 



In his work on "The Phosphate Rocks of South Carolina,'* 

 Professor Francis S. Holmes tells us, in reference to their discovery, 

 that in November, 1837, in an old rice field about a mile from the 

 west bank of the Ashley River, in St. Andrew's Parish, he found a 

 number of rolled or water-worn nodules of a rocky material filled 

 with the impressions of marine shells. These nodules or rocks were 

 scattered over the surface of the land, and in some places had been 

 gathered into heaps so that they could not materially interfere 

 with the cultivation of the field. As these rocks contained little 

 carbonate of lime (the material of all others then most eagerly 

 sought after), they were thrown aside and considered useless as a 

 fertilizing substance. In December, 1843, in another old field he 

 attempted to bore with an augur below the surface to ascertain the 

 nature of the earth beneath, with the hope of finding marl. On 



