APPENDIX, 335 



Upper Menominee, to the district of the Totosli and Cradle- 

 Top Mountains, west of Chocolate Eivcr, on the shores of Lake 

 Superior. 



I observed the crystalline sandstone and its overlying cliff 

 limestone, along the valley of the Wisconsin, where ancient exca- 

 vations for lead ore have been made. There is an entire preserva- 

 tion of its characters, and no reason occurs why its mineralogical 

 contents should not prove, in some positions, as valuable as they 

 have been found in Missouri, or in the Dubuque district west of 

 the Mississippi. 



On reaching the "Wisconsin Portage, the limestone is found to 

 have been swept by diluvial action, from its supporting sand rock. 

 Such is its position not far north of the highest of the four lakes, 

 and again at Lake Puck way, in descending the Fox Eiver ; 

 consequently, there are no lead discoveries in this region. On 

 coming to the calcareous rock, which is developed along the chan- 

 nel of the river, below Winnebago Lake, it appears rather to 

 belong to the lake system of deposits. Its superior stratum 

 lies in patches, or limited districts, which appear to have been 

 left by drift action. Petrefactions are found in these districts, 

 and the character of the rock is dark, compact, or shelly. The 

 lower series of deposits, such as they appear at the Kakala 

 Eapids, at Washington Harbor, in the entrance to Green Bay, 

 and in the cliffs north of Sturgeon Bay and Portage, are mani- 

 festly of the same age and general character as the inferior stratum 

 of Michilimackinac and the Manatouline chain. 



Basin of Lake Michigan. — This basin, stretching from the 

 north to the south nearly four hundred miles, lies deeply in the 

 series of formation of limestones, sandstone, and schists, to which 

 we apply the term of the Michilimackinac S3^stem. Its north and 

 west shores are skirted from Green Bay to a point north of the 

 Sheboygan, with the calcareous stratum. At this point, the 

 ancient drift, the lacustrine clay of Milwaukie and the prairie di- 

 luvium of Chicago, constitute a succession, of which the surface 

 is a slightly waving line of the most fertile soils. 



Among the pebbles cast ashore at the southern head of this lake 

 1 observed slaty coal. It seems, indeed, the only one of the lakes 

 which reaches south into the coal basin of Illinois. If the level 

 at which coal is found on the Illinois were followed through, it 



