x ii PREFACE. 



without a reference to their obvious cause. Generalization should follow 

 the accumulation of facts, not precede them. In order to give complete- 

 ness to the survey, these facts ultimately will be grouped, and their true 

 relations set forth. But this cannot be done till the whole state has been 

 surveyed. 



At best this is but a preliminary investigation of the geology and 

 geography of the state. It adds definiteness and fullness to the work of 

 Nicollet and of Owen; but it rests on data, appliances, and resources too 

 limited and inexact to warrant the expectation that the future will not 

 find fault with it, and will not be able to extend it by still more thorough 

 and pains-taking study. It is to be hoped, therefore, that in the submission 

 of this work to the scrutiny of the geologist of to-day, and to the verdict of 

 the geologist of the future, they will both scan its pages with due leniency 

 for its errors and imperfections. 



It would be useless to attempt to enumerate tlie individuals and cor- 

 porations to which the survey is under obligation. Throughout the state 

 its agents, and all its efforts, have been received, with scarcely an excep- 

 tion, with perfect cordiality and cooperation. It has been a constant effort 

 to make the survey useful, in every way, and a free avenue of information 

 to the people respecting everything that is included within its scope. This 

 has entailed a voluminous correspondence, but one which often has re- 

 sulted in benefit to the survey as well as to the inquirer. In the prepara- 

 tion of the historical chapter, however, the generous assistance of Rev. E. 

 D. Neill should be specially mentioned; who placed his rich library of 

 historical works, and several unpublished manuscripts and early maps of 

 the Northwest, unreservedly at the service of the writer. General Q. A. 

 Gillmore kindly superintended the testing of eighty two-inch cubes of 

 building stone. Hon. D. S. Durrie, librarian of the Wisconsin historical 

 society, has loaned several rare books which could not be procured in 

 Minnesota. The gratuitous aid rendered in 1874 by Prof. M. W. Harring- 

 ton, appears essentially in the reports on three counties. 



N. H. W. 



