ANNUAL KEPORT FOR 1874. 53 



and Mr. F. II. King was engaged to continue his observations upon 

 animal and vegetable life, such as are required by the provisions of 

 the law authorizing the survey. Two thousand five hundred miles of 

 travel with a team ; seven thousand specimens of rocks, fossils, and 

 minerals collected; these are justly deemed a good season's work. 



Prof. Chamberlin's report of his operations during the year 1874 

 will be found to contain ample details of the geology of the district 

 assigned to him. These will settle many questions as to the non- 

 occurrence of coal and other useful minerals, which are dependent up- 

 on the kind of rock found. The difficulty of determining the proper 

 order of succession of the various strata, with their general dip and 

 strike in a region where outcrops can be only here and there exam- 

 ined, is very great. Hence, perhaps there may still remain some im- 

 portant questions for future investigation; but sufficient has been 

 ascertained, it is believed, to answer all the general objects and pur- 

 poses of this survey. 



Attention is called, in this report, to the great valley diverging 

 from the west shore of Lake Michigan towards the southwest, well 

 marked by the waters of Green Bay, Lake Winnebago and the valley 

 of Rock river; the rock ridge bordering this great ancient valley on 

 the east; the very remarkable drift ridge, locally known as the potash 

 kettles, extending from the south line of the state to the peninsula 

 of Green Bay; the several systems of parallel drift ridges, some of 

 them sharp and narrow, called hog's backs; and the more level dis- 

 tricts along the immediate shore of the lake. 



A very important and interesting deduction made by Prof. Cham- 

 berlin, as a result of his explorations, is the fiord character of the 

 peninsula of Green Bay; this being the result of intense glacial ac- 

 tion, perhaps near the close of the great ice period. The glacier 

 seems to have been concentrated upon Lake Superior by the converg- 

 ing shore lines, and passing southward to Green Bay, was thence di- 

 verted towards the southeast, plowing six or more great furrows, 

 which are now indicated by bays on both sides of the peninsula. 

 These valleys, or fiords, are continuous across this narrow neck of 

 land, and may be traced on the charts of the lake survey upon the 

 bottom of Lake Michigan, for a distance of twelve or fourteen miles. 

 If the peninsula north of Sturgeon Bay was ever covered with 

 drift, it has been entirely removed, perhaps by the abrading action of 

 waves at a time when Lake Michigan stood at a much higher level 

 than now ; the rock surface being now covered only with a thin layer 

 of soil, destitute of drift material. 



Some very remarkable facts relating to the course of streams are 



