APPENDIX. 361 



Hints may thus be derived of value to the future commerce 

 of the country. Scarcely any of the new states are without 

 indications of the existence of salt. Every day is adding to the 

 number of localities. 



In the region ivest of the Mississippi, I was informed that salt 

 occurs, in the crystallized form, in the territories of the Yanktons, 

 who inhabit the flat country at the sources of the Eiver St. Peter's. 

 In certain parts of these plains, the salt exists on the surface. It 

 is mixed with earth, in specimens brought to me, but crystallized 

 in cubes, very imperfect, of a gray or grayish- white color. The 

 Indians scrape it up from certain parts of the prairies or plains, 

 where the salt water is prevented from draining off. 



2. Alkaline Sulphate of Alumina. 



This salt exists, in the form of efflorescences, in the cavities and 

 fissures of rocks along the southeast parts of the shores of Sagana 

 Bay, Lake Huron, and in the argillaceous formations at Erie, on 

 Lake Erie, Pennsylvania. 



These positions embrace the principal localities of minerals 

 noticed. In travelling rapidly through a remote wilderness, there 

 was but little opportunity to explore off the track ; and the whole 

 observation was confined to the mere surface of the country, which 

 is much obscured by diluvial and alluvial formations. 



It will be seen that the region of Lake Superior has been a 

 fruitful field for mineralogical inquiry, and it is one which invites 

 further exploration. Its mineralogy affords a variety of interest- 

 ing substances which are objects of scientific research, and it may 

 be anticipated to be the future theatre of extensive mining opera- 

 tions. The country northwest of Lake Superior, and the Upper 

 Mississippi north of the Falls of St. Anthony — consisting mostly 

 of upheaved primitive rocks and the pebble-drift, or diluvial, form- 

 ations — has furnished but few subjects of mineralogical remark. 



The district of country between the Falls of St. Anthony and 

 Prairie du Chien, in common with the more southern portions of 

 the Mississippi Valley, partakes of all the interest which the 

 mineral kingdom presents in a calcareous and metalliferous country 

 of secondary formation. It has added considerably to my collec- 



