INTRODUCTION. 



xix 



metes and bounds. The Lower Sandstones (lowest protozoic strata) will be seen 

 coming to the surface on the east side of the Upper Mississippi, north of the Wis- 

 consin River. They doubtless underlie, also, the extensive drift and the Red Marls 

 and Clays, of the Lake Superior country ; there assuming a red tint and ferruginous, 

 argillaceous character. 



To these succeeds the Lower Magnesian Limestone, which appears on both sides 

 of the Upper Mississippi, southwest of the Lower Sandstones, and partially inter- 

 sected by narrow belts of the same, where they crop out beneath it, in the deep cuts 

 of the streams, or rise to the surface along the bearings of partial axes of upheaval. 



Next supervenes the Upper Magnesian Limestone, with its underlying shell-beds, 

 its lead-bearing strata, and its coralline and pentamerus subdivisions : all lying 

 south of the two preceding. 



Southwest, again, we come upon the Cedar Limestones, cotemporary with the 

 Devonian formation of English geologists ; separating the Magnesian Limestones of 

 the north from the Carboniferous Limestones and the great coal-field of Iowa and 

 Missouri. 



The intervening country, lying chiefly towards the head waters of the Mississippi 

 and its tributaries, and on Red River, is overspread with drift. The latter occu- 

 pies, in this district, not only a much greater area than any one of the above 

 described formations, but nearly as much as all of them put together. 



Underlying the whole of these formations, but showing themselves only over 

 limited tracts, either in cuts of the streams, or where they protrude in dikes or 

 ridges upheaved by igneous action, are the crystalline and metamorphic rocks. 



The geological formations of the district proper range, therefore, from the granite 

 to the top of the coal-measures; above which latter, except superficial deposits, 

 no geological group has been detected ; no New Red, whether Permian or Triasic ; 

 no Cretaceous System ; no Tertiary Basin.* 



Over this entire region of country (with the exception of that part of North- 

 western Minnesota which lies between the British line of the north shore of Lake 

 Superior) it will be wholly unnecessary, hereafter, to institute further examina- 

 tions having reference to mineral reservations. The fact has been reliably ascer- 

 tained, that it contains no lands, which, following the usual rules adopted by the 



* The cretaceous and tertiary formations incidentally noticed in this Report lie beyond the limits of 

 the district, west of the Missouri River. It is not improbable, however, that cretaceous strata may underlie 

 the drift in the extreme northwestern corner of Iowa, sweeping around the confines of the carboniferous 

 limestone, east and west of the Sioux River. 



"{" This region of country may, on closer examination, be found to contain valuable minerals, suitable 

 for reservation. But as it is still the property of the Chippewas, no mineral reservations could, with 

 propriety, be made ; nor, as it is still undivided, even by meridian lines, were any such reservations, by 

 metes and bounds, practicable within it. 



