32 THE GEOLOGY OF MINNESOTA. 



[Schoolcraft, 1820. 



but the river rushes with the utmost velocity down a highly inclined rocky 

 bed toward the northeast." " Immediately 



above the fall is a small rocky island bearing a growth of spruce and 

 cedars." 



Schoolcraft states that the Mississippi, instead of having its source in 

 Cass lake, or even in Turtle lake, enters Cass lake from the south at a dis- 

 tance of eight or ten miles from the mouth of Turtle river.* 



Mr. Schoolcraft's geological and mineralogical resume of the expedition 

 is quite full, but embraces much territory beyond the limits of Minnesota. 

 He is the first to give a geological account of the lower valley of the St. 

 Louis river, but his statements about its tributaries being from " the north- 

 west of the Rainy lakes," and Vermilion lake tributary to its volume, while 

 in'keeping with a general looseness in his statements, show still a lack of 

 geographical knowledge of that region. He estimates its descent from Knife 

 falls, through the " Cabotian Mountains," at about 418 feet. He says that 

 the red sandstone at Fond du Lac is succeeded, up the river further, by 

 " trap, argillite and grauwacke." * * * " The river is continually in a 

 foam for nine miles, and the wonder is that such a furious and heavy volume 

 of water should not have prostrated everything before it. The sandstone, 

 grauwacke, and the argillite, the latter of which stands on its edges, have 

 opposed but a feeble barrier ; but the trap species, resisting with the firm- 

 ness, as it has the color, of cast - iron, stand in masses which threaten the 

 life and safety of everything that may be hurled against them. I found a 

 loose specimen of sulphuret of lead, and some common quartz, in place in 

 the slate rock, a vein of chlorite slate, and a locality of coarse graphite, to 

 reward my search." 





*Reaulting from the expedition of Gov, Cass, were several scientific papers, which at the date of their publication 

 were valuable additions to the natural history of the region, viz: 



1. Results of observations for latitude and longitude during the expediton of 1820. By Capt. David B. Douglass. 



2. Report on the copper mines of lake Superior. H. R. Schoolcraft. 



3! Observations on the Mineralogy and Geology of the country embracing the sources of the Mississippi river and 

 the Great Lake Basins. By Henry R. Schoolcraft. 



4. Report in reply to a resolution of the U. S. Senate on the value and extent of the mineral lands on lake Supe- 

 rior. By Henry K. Schoolcraft. 



5. Rapid glances at the Geology of Western New York, beyond the Rome summit, in 1820. By Henry R. School- 



' 6. A memoir on the Geological position of a fossil tree in the secondary rocks of Illinois, 1822. By Henry R. 



7 List of plants collected by rapt. D. B. Douglass, at the sources of Ue Mississippi river. From the 4th Volume 

 of Silliman's Journal of Science. By Dr. John Tol rey . 



8 A letter embracing notices of the Zoology of the Northwest, addressed to Dr. Mitchell, on the return of the 



>C 9 '^Species of Bivalves collected by Mr. Schoolcraft and Capt. Douglass in the Northwest. From the Cth Volume 

 of the American Journal of Science. D. H. Barnes. 



10 Fresh water shells collected by Mr. School raft in the valleys of the Fox and Wisconsin rivers. From the 5th 

 Volume of the American Philosophical Transactions. By Isaac Lea. 



11 Summary remarks respecting the Zoological species noticed in the expedition. By Dr. Samuel L. Mitchell. 



12 Xu biuartu*. Medical Repository. Vol .21. By Dr. Samuel L. M.tchell. 



13~ Srfuru* Iridccem-striaUui. Medical Repository, Volume 21. By Dr. Samuel L Mitchell. 



H' Proleus of the lakes. Am. Jour. Sci., Vol 4. Dr. Samuel L. Mitchell. 



15 Memoranda on Climatic Phenomena and the Distribution of Solar Heat, in 1820. By Henry R. Schoolcraft. 



