Qeobgy and Mineralogy. 1 53 



the head of Green Bay, and the Wisconsin, which empties into 

 the Mississippi at Prairie du Chien, come within a mile and a half 

 of one another, at hen, Is in each, near Portage City, where a 

 granite ridge lies near the surface. The summit of this Portage 

 region is about 218 feet above Lake Michigan, and 188 above , F,o 

 Uioh.-il.pi, and the summit of this water level 2084 and 178* 

 feet. The stream from Portage eastward (Fox River) passes 

 through La; dcs three smaller lakes), with a 



descent of 39 feet, and then plunges down the remaining I69J 

 feet along a limestone u'or-e whose sides are liltv the. or le-s in 

 height. ° ° y 



The region of Lake Winnebago is bordered on the west by a 



■ ■ ■..,,■; . 



■ 

 "» the view thai the whole alluvial area was originally ;a lake ; at 



feet, so that the westward flow would have neees-arilv taken place 

 were the water, at the In font required to make the lake. After- 

 vn 'h , w, . .u, v„l 11( , i„ the , nth ht> tal whnhdetir- 



lope, tow n i ' t ni_ thu- tin 



, Ir .l Tlot tl,;= oviKoirlonpn nppnriwl after 



ft from the alluvial p 



The facts : -e tliev tend to prove 



that the gub ! (that following the 



-heaai;.- .:. of the Continent, ill 



> - 1 I i ,n_ t ^ 1 tj.nl 



. ■ - 

 of change of level. 



General Warren obtained the same proofs of a northward sink- 



■ _ 1 , i „ • tbmi the Upper 



. 



