GEOLOGICAL SURVEY OF IOWA. 



INTRODUCTION. 



1. HISTORICAL. 



By act of the General Assembly of Iowa, in January, 1855, 

 a geological survey of the State was ordered, and immedi- 

 ately afterwards Prof. James Hall, of Albany, New York, 

 was appointed State Geologist, and Prof. J. D. Whitney, of 

 Northampton, Massachusetts, as Chemist and Mineralogist. 

 The work was continned during subsequent years, Mr. A. H. 

 Worthen, now State Geologist of Illinois, acting a part of the 

 time as field-assistant, when in the winter of 1858-9 their final 

 report was printed in two volnmes by order of the General 

 Assembly. 



This work has now been before the public more than ten 

 years and its merits are well known. It was expected by those 

 then having the work in charge, and also contemplated by the 

 General Assembly that ordered it, that it wonld be continued 

 until the whole State had been carefully examined and re- 

 ported npon. 



Consequently that report embraced only the results of labor 

 performed in the east half of the State ; and a full considera- 

 tion also of mnch of the economic geology of that half was 

 omitted. 



No provision was subsequently made for continuing the 



