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a deposite of limestone, which is sometimes magnesian, and occasionally 

 contains fossils ; the whole covered by what I have called the erratic de- 

 posite. 



The sandstone forms the Little Rapids of the St. Peter's, and, reappear- 

 ing at the Traverse des Sioux, determines other rapids that are observed 

 in a beautiful stream two miles NE. of the trading post in this place. 

 At other intermediate localities, the sandstone and limestone both appear ; 

 but further on, the limestone disappears altogether; because it goes thin- 

 ning out as the western limits of the formation are approached. This may 

 be observed near the Waraju, and towards the upper parts of the Mankato, 

 where the limestone, and indeed the sandstone, are replaced by beds of clay 

 or of calcareous marl. 



In the argillaceous deposites last referred to, there are red ochre, other 

 ferruginous minerals, and lignites. Between the sandstone and 



inera ogy. ^j^^ limestone there is a bed of whitish clay, enclosing nodules 

 of the blue earth ; and sometimes, between the strata of limestone, bands 

 of argillaceous iron ore, intermixed with siliceous and calcareous incrusta- 

 tions. 



The account given above applies equally to the rocky cliffs on the upper 

 part of the La Houtan river, and especially to the interesting locality at the 

 entrance of its south fork, which is four miles to the east of lake Ti-tanka- 

 tanrmian. 



Those who have read the travels of Baron de la Hontan, in which he 

 La Honian mentions his discovery of a certain long river coming from the 



river. west, and falling into the Mississippi, may, perhaps, think that, 

 by giving his name to a river upon my raap, I meant to clear up the 

 doubt which has existed, for more than 150 years, as regards the veracity 

 of this officer. 



Such was not originally ray intention ; but I am forced into it after ter- 

 minating my exploration of the Undine Region. Having afterwards pro- 

 cured a copy of La Hontan's book, in which there is a roughly-made map 

 of his long river, I was struck with the resemblance of its course, as laid 

 down, with that of Cannon river ; which I had previously sketched in my 

 own field-book. 1 soon convinced myself that the principal statements of 

 the Baron in reference to the country, and the few details he gives of the 

 physical character of the river, coincided remarkably with what I had laid 

 down as belonging to Cannon river. 



Thus the lakes and swamps corresponded ; traces of Indian villages 

 mentioned by him might be found in the growth of a certain grass that 

 propagates itself around all old Indian settlements. Some ol the names 

 which he assigns to them may be referred to dialects of the Sioux tongue ; 

 and even his account of the feasting of his men on the large number of 

 (he American hare which he found there, is substantiated by the voyageurs. 



His account, too, of the mouth of the river is particularly accurate. The 

 most scrupulous geographer, describing it at this time, would have but little 

 to alter. As this locality is in the way of travellers going to St. Peter's, I 

 will quote from the text of La Hontan, so that they may judge of the truth 

 of my assertion, 



" We entered (he says) the mouth of this long river, which is a sort of 

 large lake filled with cane-brakes (jones;) in the midst of which we dis- 

 covered a narrow channel, which we followed up," (fee. 



