2 LETTER TO THE GOVERNOR. 



unexpended in the treasury, would be sufficient to do this if it is decided not to 

 complete the whole work in an exhaustive manner. Should the next General 

 Assembly desire it, the additional work can be accomplished within the next two 

 years by myself and my able assistants during the vacations of the institutions 

 with which we are respectively connected. 



As the former geological report, made under the direction of Prof. James 

 Hall, of Albany, New York, was devoted exclusively to the eastern half of the 

 State, the labors of the Survey as organized under my own direction have been 

 largely devoted to the western half. However, so for as the mineral and other 

 material resources of the State are concerned, it has been my object to present 

 them as fully as practicable in this report without regard to the part of the State 

 in which they occur. In presenting the general geology of the whole State, as 

 well as some of the details of that of its eastern half, I have necessarily repeated 

 some of the matter contained in that former report, but even this is largely the 

 result of observations made by the different members of the Survey as at present 

 organized. This limited repetition was thought to be desirable rather than 

 objectionable from the fact that, the former report being out of print, very few of 

 those into whose hands this report shall fall would otherwise be able to obtain a 

 general view of the geology of the whole State. The chapter in the former 

 report by Prof. J. D. Whitney upon the lead mines of Dubuque, presented the 

 subject in so complete a manner and the account of his labors there given has 

 proven so reliable and satisfactory after a lapse of more than ten years, that I 

 have deemed it unnecessary to make any special examination of that region, and 

 have necessarily confined myself there to such investigations only 'as subsequent 

 time has suggested as supplemental to his labors. There would be great pro- 

 priety in republishing Prof. Whitney's report upon the Dubuque lead mines. 

 With this exception, I have endeavored to embrace all the important matters 

 connected with the geology of the State, giving especial attention to such 

 subjects as pertain to its material wealth ; leaving those of a more abstract 

 scientific character to a future time. 



This report, therefore, embraces the following subjects, namely : 



1. Physical Geography and Surface Geology, including observations upon the 

 soils and sub-soils, drainage systems, general topography, etc., with numerous 

 illustrations. 



2. Gener.il Structural Geology of the whole State illustrated by maps and 

 diagrams. 



3. County and Regional Geology, especially considered and illustrated. 



4. Mineralogy, Lithology, and Chemistry, including, besides the Chemist's 

 report, an account of the stone, clays, minerals, etc., of the State and of their 

 economic value. 



Referring more definitely to some of the many important and interesting sub- 

 jects that have engaged the attention of myself and my assistants, I may mention 

 the satisfactory solution of the question as to the relative position of the strata 

 that underlie and overlie the coal-bearing formations and the determination of 

 their dips and trends. As a result of this, the opinion is confidently expressed 



