INTRODUCTION. 
By N. S. Shaler. 
The circumstances which have led to the preparation of the sub- 
joined report on mineral phosphates are as follows, viz: In 1870 the 
present writer was employed by the Superintendent of the Coast Sur- 
vey, the late Benjamin Peirce, to examine the phosphate beds of South 
Carolina with a view to determining the limits of that field; it was 
also deemed desirable to ascertain, if possible, the conditions which led 
to the formation of the deposits. 
It was at that time the intention of Professor Peirce to have the 
geology of the belt of country within the limits of the Coast Survey 
maps carefully determined, so that they might be shaped in a way that 
would better serve the commercial interests of the country and also 
have a greater scientific value. After a time it appeared that there 
were legal difficulties in the way of publishing these studies in the re- 
ports of the Coast Survey aud this work was suspended. It was the 
hope of Professor Peirce to secure a modification of the law, but before 
this was accomplished he retired from the post of Superintendent and 
his successor deemed it best to abandon the project. During the two 
years in which I was engaged in this work on the geology of the coast 
line I became very much interested in the problems connected with the 
origin and distribution of phosphatic deposits. From 1873 to 1880, 
while employed as State geologist of Kentucky, I had a chance to see 
a good deal of the somewhat phosphatic limestones of the CambroSi- 
lurian sections, a set of beds which, by their decay, have given great 
fertility to the soils that lie upon them. The researches of Dr. Robert 
Peter, the chemist of that survey, made it plain that the phosphatic 
contents of the soils are among the first materials to be exhausted by 
the careless tillage which characterizes our American agriculture, and 
that they are the most costly to restore to the soil. 
Extending the general inquiry to the grain-producing districts which 
lie to the north aud west of Kentucky, it became evident that all those 
States, which are now the granary of this country aud the chief source 
of supply for European markets as well, are rapidly exhausting their 
soils and will soon be in grave need of phosphatic manures. The im- 
(483) 9 
