210 NAKRATIVE OF THE EXPEDITION. 



CHAPTER XX. 



Topogrftphical survey of the northern shores of Green Bay and of the entire basin of 

 Lake Michigan — Geological and Mineralogical indicia of the coast line — Era of 

 sailing vessels and of the steamboat on the lakes — Route along the Hxivon coast, 

 and return of the expedition to Detroit. 



The coast line traversed by the party detached from Green 

 Bay on the 22d of August, under Mr. Trowbridge, extended from 

 the north shore of Fox River to the entrance of the Monominee 

 River, and thence around the Little and Great Bay de Nocquet, 

 to the northwestern cape of the entrance of Green Bay. From 

 the latter point, the northern shore of Lake Michigan was traced 

 by the Manistic, and the other smaller rivers of that coast, to the 

 northern cape of the Straits of Michilimackinac, and through 

 these to Point St. Ignace and the Island of Michilimackinac. The 

 line of survey, agreeably to their reckoning, embraced two hun- 

 dred and eighty miles, thus closing the topographical survey of 

 the entire coast line of the basin of Lake Michigan, and placing 

 in the hands of Captain Douglass the notes and materials for a 

 perfect map of the lake.* 



Mr. Trowbridge, whom I had requested to note the features of 

 its geology and mineralogy, presented me with labelled specimens 

 of the succession of strata which he had collected on the route. 

 These denoted the continuance of the calcareous, horizontal series 



* It is to be regretted that Capt. Douglass, who, immediately on the conclusion 

 of this expedition, was appointed to an important and arduous professorship in the 

 U. S. Military Academy of West Point, could not command the leisure to complete 

 and publish his map and topographical memoir of this part of the U. S. So long 

 as there was a hope of this, my report of its geology, &c., and other data intended 

 for the joint pdblic wokk, were withheld. But in revising this narrative, at this 

 time, they are submitted in the Appendix. Prof. Douglass, of whose useful and 

 meritorious life, I regret that I have no account to oifer, died as one of the Faculty 

 of Geneva College, October 21, 1849. 



