INTRODIICTORY AND HISTORICAL. 647 



Previous Publications and Surveys. The first geological survey 

 embraced the extensive district lying between the Missouri river and 

 Eed river of the North, and included the upper part of the valley of 

 the Mississippi and the mining districts adjacent to that river. It 

 was undertaken in i83i,.and completed in 1835, by the general gov- 

 ernment, and placed in charge of Gr. W. Featherstonhaugh. 



The next survey was also instituted by the general government, 

 and placed under the direction of Dr. D. D. Owen, in the fall of 

 1839, and completed by him in the same year; its object being to as- 

 certain the geographical position of the Lead region and its value as 

 mineral land. Dr. Owen was afterward engaged in the geological 

 survey of the Chippewa Land District, during 1847-8, of which he 

 jjublished a final report in 1851, accompanied by a general geological 

 map. The exploration of so large a district did not admit of a mi- 

 nute examination of any particular part: thus, the space devoted to 

 the southwestern part of the state, and lying south of the Wisconsin 

 river, is comprised in about twenty pages of chapter I. 



The next geological survey was undertaken under the auspices of the 

 state, in 1853, and placed in charge of Prof. E. Daniels, who published 

 in 1854 a pamphlet concerning the Lead region. He was then suc- 

 ceeded by Dr. J. O. Percival, who held the position of State Geolo- 

 gist, until his death, in May, 1856. He published two reports of 

 about 100 pages each, which contain much valuable information, and 

 bear evidence of the careful research which always distinguished his 

 work. 



To complete the survey interrupted by the death of Dr. Percival, 

 Profs. James Hall, E. S. Carr and E. Daniels were appointed; and, in 

 1858, Prof. Daniels published a rejjort of about 60 pages, on the iron 

 ores of Wisconsin. This was succeeded by the report of Profs. Hall 

 and Whitney, in January, 1862. This was by far the largest report 

 that had been published concerning the Lead region. It comprised 

 about 450 pages, of which 300 were devoted to that district. This 

 report was accompanied by a crevice map of the mineral ranges, and 

 a general geological map of the Lead region. The latter, so far as it 

 was made from.personal observation, was quite correct; but it still left 

 much to be desired in this department; which deficiencies, it is be- 

 lieved, have been supplied by the present survey. 



For ten years the G-eological survey was discontinued. The next, 

 being the examinations of Kev. John Murrish, of which he published 

 a report in 1872, in a pamphlet of sixty-five pages. 



Topographical and Geological Maps and Sections. A great deal 

 of time has been devoted to the construction of the maps accompanying 



