: INTRODUCTION. X1X 
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. 7 
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. 
