APPENDIX. 333 



consin, the Montreal, and the St. Croix Rivers, with which it 

 originates. 



Trompeldo {Le Montaine des Tromps cVEaux). — This ishand 

 mountain stands as if to dispute the passage of the Mississippi, 

 whose channel it divides into two portions. Distinct from its 

 height, which appears to correspond with the contiguous cliffs, 

 and in the large amount of fresh debris at its base, it presents 

 nothing peculiar in its geology. 



Painted Rock. — This vicinity is chiefly noted for its large and 

 fine specimens of fresh- water shells. 



Wisconsin. — Like the Chippewa, this stream brings down in 

 its floods, vast quantities of loose sand, which tend to the forma- 

 tion of bars and temporary islands. It originates in the same 

 elevated plains, and bespeaks a considerable area at its sources, 

 which must be arid. It is a region, however, in which lakes and 

 rice lands abound, and it may, in this respect, be geologically of 

 the same formation as the higher plateaux of the Mississippi, 

 above the Sandy Lake summit. Its sides produce many species 

 to enrich our fresh-water Conchology. 



Lead Mines of Peosta and Dubuque. — In my researches 

 into the mineral geography of Missouri, in 1818 and 1819, I had 

 explored a district of country between the rivers Merrimak and 

 St. Francis, and on the Ozarks, which revealed many traits which 

 it has in common with the Upper Mississippi. There, as here, 

 the mineral deposits appear to be, in many cases, in a red 

 marly clay, whether the clay is overlaid by the calcareous rock 

 or not. There, as here, also, the limestone and sandstone strata 

 are perfectly horizontal. The leads of ore appear, in this section, 

 to be followed with more certainty, agreeable to the points of the 

 compass ; but this may happen, to some extent, because the prac- 

 tice of mining on individual account, with windlass and buckets, 

 in the Missouri district, has led common observers to be more 

 indifferent to exact scientific methods. To say that the digging, 

 at these mines, is equally, or more productive, is perhaps just. 

 Capital and labor have been rewarded in both sections of the 

 country, in proportion as they have been perseveringly and 

 judiciously expended. 



I found much of the ore, which is a sulphuret, at Dubuque's 

 Mines, lying in east and west leads. These leads were generally 



