CURRENT PRE-CAMBRIAN LITERATURE 749 
Van Hise* describes baselevels in the crystalline rocks of central 
Wisconsin and Keweenaw Point. In the Wisconsin district the 
Archean and Huronian rocks occupying the area are truncated to an 
even baselevel with an apparent southerly slope. The altitude is 
about 1450 feet. 
On Keweenaw Point the peaks of the main trap range rise to so 
nearly the same altitude that they form an apparent plain, which is 
considered an ancient baselevel. The altitude of this plain is about 
1350 feet. Certain peaks, consisting of hard quartz-porphyry and 
felsite, have resisted weathering, and stand above this plain. 
The central Wisconsin plain has not been so deeply dissected as 
the Keweenaw Point area, but this is explained by the fact that it is not 
so near either of the great lakes, and therefore erosion has not been so 
effective over it. 
From the proximity of the central Wisconsin and Keweenaw Point 
baselevels, and from the fact that they have nearly the same altitude, it 
is concluded that the baselevels of the two districts are probably but 
parts of a far more extensive baseleveled region resulting principally 
from the subaérial erosion of Cretaceous time, and perhaps also, in 
part, from the marine denudation of the Cretaceous. 
Hubbard * describes the relation of the copper vein at the Central 
mine, Keweenaw Point, to the Kearsarge conglomerate. The veins of 
Keweenaw Point belong largely to one system, and are confined 
principally between T 57 N, R 32 W, and the northeast extremity of 
the Point. The copper-bearing formation between these limits dips 
N 33° E, at the first locality, to south of east at the last, and the veins 
are nearly at right angles to the formation. The Central mine is 
situated in Sec. 23, T 58 N, R 31 W, about eighteen miles northeast of 
Calumet. Here there has been a northerly sliding of the formations 
above the Kearsarge conglomerate, as a result of which the copper 
vein in the overlying formations is found to stop abruptly at the 
Kearsarge conglomerate. In this mine is the eastern edge of the 
basin in which the Kearsarge conglomerate was deposited. 
*C. R. VAN Husk, A central Wisconsin baselevel, Science, Vol. IV, 1896, pp. 
57-59; A northern Michigan baselevel, 2dzd., pp. 217-220. 
* The relation of the vein at the Central mine, Keweenaw Point, to the Kearsarge 
conglomerate, by L. L. Husparp, Proc. Lake Superior Mining Inst., Vol. III, 1895, 
pp. 74-83. 
