ON THE 



FRESH-WATER GLACIAL DRIFT OF THE NORTHWESTERN STATES. 



I HAVE had opportunities during the past twenty-five years, of examining the 

 superficial materials which overlie the indurated rocks, in six of the Northern and 

 Western States, and covering the territory north of the Ohio river and east of the 

 Mississippi, to the national boundary. The length north and isouth of this area 

 is about eleven degrees of latitude, from the 38th to 49th, its breadth being quite 

 irregular. On the east its boundary is the middle line of the North American 

 lakes from Erie to Superior, and thence northwesterly along Pigeon river and Rainy 

 Lake river to the Lake of the Woods. Over this space I have found what I 

 conceive to be but one formation belonging to the quaternary or post tertiary, 

 having three members. This formation is wholly of fresh water origin, having 

 as yet furnished no specimen of a marine or salt-water character. 



To the eastward of Lake Erie, in the valleys of Lakes Ontario and Champlain, 

 and along the St. Lawrence, the shells of the drift are wholly marine. The external 

 characters of the clays in which they are imbedded does not diff'er materially from 

 those of Lakes Erie, Huron, and Superior, except in color. Farther examination 

 in Northern New York, and on the Canada side of the St. Lawrence, will probably 

 show that the terraces and sand ridges at the west end of Lake Ontario overlap the 

 marine drift towards the east, and are therefore more recent. The ridges and ter- 

 races of Lake Ontario extend westerly and connect with those of Lake Erie, which 

 run into those of Lakes St. Clair, Huron, and Michigan, forming one system. They 

 reach up the bays and indentations of the coast of all the lakes, and up the valleys 

 of the rivers. 



The ridges are composed of water-washed sand, in which are buried timber, leaves 

 and fragments of trees, of varieties now existing in North America, but principally 

 of a northern growth. Buried timber of the same varieties is common through the 

 entire depth of the superficial materials. Shells are not frequent, but when found 

 are well preserved. The thickness of the drift is very variable, reaching, occasion- 

 ally, 600 to 1,000 feet; though this is unusual, for it seldom exceeds 200 to 300 

 feet. This great fresh-water formation, there is reason to believe, extends northerly 

 and westerly on this continent much farther than I have examined it. Various 

 names have been used in describing it, some of which are local, and others intended 

 to represent its age in the "Geological Series." I use the term "glacial drift" 



1 April, 1866. ^ 1 'i 



