LECTURE OF PROF. AGASSIZ. 161 



THE ORIGIN OF THE AGRICULTURAL SOIL. 



BY PROF. LOUIS AGASSIZ. 



Mr. President, Ladies and Gentlemen, — On an occasion like 

 this, it has occurred to me that a few remarks upon the origin 

 of the agricultural soil would be in place. 



It is unquestionable that all material upon which agriculture 

 depends is the result of the decomposition of rocks ; but I 

 believe that there is a misapprehension upon this subject when 

 it is considered in detail. It is believed by many that the soil 

 which we till owes its existence to the rocks underlying the soil. 

 That is not the case. There is hardly anywhere in the world an 

 extensive tract of cultivated soil which has not been brought to 

 the place where it exists from considerable distances ; and I 

 want to try to show you how that soil has been ground to pow- 

 der and prepared for the purposes and uses of man. I allude 

 here to the soil that has not yet been submitted to agricultural 

 processes. I do not intend to include in my remarks the im- 

 provements which are made upon soil by manuring, nor the 

 improvements which naturally result from the decomposition of 

 the plants which in their wild condition decay upon that soil, 

 nor to allude to the part which the decay of successive genera- 

 tions of animals contribute to that improvement. My intention 

 is simply to allude to the origin of the unimproved soil which 

 lay on the surface of the ground, forming the solid crust of the 

 earth. And in bringing this subject before the Board of Agri- 

 culture and before those who feel an interest in their proceed- 

 ings, it is my desire to suggest the propriety of making a geo- 

 logical survey of the agricultural ground as a means to improve 

 agriculture. The State of Massachusetts has already ordered a 

 geological map, which was executed in a most admirable man- 

 ner by a gentleman whose scientific career has been spent among 

 you in this place. I need hardly name President Hitchcock to 

 recall one of the prominent geologists of America, and one who 

 has done excellent work in popularizing science on this conti- 

 nent, and in making known to the whole civilized world the 

 geological structure of the State of Massachusetts. But the 

 work which President Hitchcock performed in that manner em- 

 braced only the rocks which form the solid foundation of the 

 country ; it was only in his later years that he turned his atten- 

 tion to what he called " surface geology." And here again he 



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