410 GEOLOGY OF CENTRAL WISCONSIN. 



most of the older states of tlie Union, in the possession of the United 

 States Linear Surveys, which have divided the whole state up into 

 townships of thirty-six square miles, and these again into sections of one 

 square mile each. Plats of each tow T nship are always to be obtained, 

 drawn to a scale of two inches to the mile, and showing marshes, prai- 

 ries, streams, and timber land; all of which are pretty closely correct 

 where crossed by the section lines, though elsewhere only roughly ap- 

 proximate. With these maps, a little trouble suffices to locate out- 

 crops with considerable accuracy, and the task becomes still easier in 

 the case of those few counties of which there are atlases showing the 

 locations of roads and houses. Notwithstanding the size of the dis- 

 trict, and the shortness of the field work, it is believed that the maps 

 accompanying this report will compare favorably in closeness of detail 

 with those made of any other states in the Union. 



The present report is the only comprehensive one ever made on the 

 area included within the Central Wisconsin district, the greater part 

 of which has, indeed, never before been geologically examined, al- 

 though a number of recoimoissances along certain lines have been 

 made in former years. About 1847, Dr. Randall, one of the. corps of 

 the United States survey of Wisconsin, Iowa and Minnesota, under 

 Dr. D. D. Owen, made a trip along Black river from the falls to the 

 Fourth Principal Meridian. His observations occupy two or three 

 pages in Dr. Owen's final report, 1 and are accompanied by one or two 

 colored sections. In the same year, Dr. J. Gr. Norwood, another of Dr. 

 Owen's corps, made a canoe trip along the Wisconsin from its source 

 to Sauk City. His observations, in the form of an itinerary, cover 

 about fifteen pages 2 of the same volume, which includes also about 

 twelve pages 8 by Dr. B. F. Shumard on the valley of the Wisconsin 

 below Portage. In 1855, Dr. J. G. Percival, then state geologist, 

 spent five months in making a general reconnoissance of the entire 

 state, visiting all but twelve counties. His report on this reconnois- 

 sance, printed after his death in May, 1856, covers about fifty pages, 

 in which each formation is taken up in regular order. Whilst this 

 report is tinctured somewhat with the older ideas, and some of its 

 statements have been since proved erroneous, and although Dr. Per- 

 cival did not have the advantages of the latest discoveries in the 

 science, and of the light now to be obtained from the geological reports 

 of adjacent states, nevertheless his general summary of the geology 

 of the state, so far as my observation goes, is an exceedingly faithful 

 one. The report was published only as a small pamphlet, and has 

 never received the credit it deserved. How far the survey under Mr. 



1 Owen's Geological Survey of Wisconsin, Iowa and Minnesota, p. 151. 

 1 Ibid, pp. 277-293. 3 Ibid, pp. 510-522. 



