170 General Notes. [Feb. 
exists along this floor of the buried channel, as shown by various 
borings at Prairie du Chien, La Crosse, and elsewhere, from 
which we learn that the bottom does not slope southward, but 
actually to the northward. Even at La Crosse, two hundred 
miles north of Rock Island Rapids, the bed of the old channel is 
fifty = pores that at the Rapids. 
Fr e above observations it is apparent that there is a 
ncaa warping across the Mississippi, which has culminated 
at Rock Island, and exposed a floor of the hard rocks to be 
eroded during later geological days. The uplift is further 
demonstrated by the observations of Mr. W. J. McGee, who 
that an old channel of the Mississippi leaves the mouth of the 
Maquoketa River, and is coincident with it for several miles, 
and then passes southward to the valley of the Wapsipenicon, 
with which it is identical to its mouth. This old valley is from 
one to three miles wide, and rises to fifty feet above the Missis- 
sippi River. It is cut not only through the Paleozoic rocks, but 
also through the Drift and Loess. The floor consists of alluvium 
only. Accordingly, the uplift or warping has been quite recent. 
As this channel is above Rock Island, its presence does not 
relieve the necessity for an explanation of the stricture in the 
valley below that place, but only shows more plainly the warp- 
ing of the strata in later geological times, which has brought 
up the old rocky floor of the region to be chiselled into by the 
waters flowing since the Drift epoch. _ 
This warping is part of a fold which extends across the conti- 
and separation of their basins. A low anticlinal extends from 
the head of Lake Ontario westward, between Lake Huron and 
Lake Erie, and beyond, as was long ago pointed out by the 
geological survey of Canada. It is along the axis of this fold 
that the Dundas valley—part of the ancient outlet of the Erie 
basin—is located, where the dip of the strata upon the southern 
<a is twenty-five to thirty-seven feet per mile to west of south, 
eighty feet and upward upon the northern side in the oppo- 
ie direction. In the peninsula (thus rendered somewhat weak) 
mae the Lakes Ontario and Erie local warpings are visible 
in many places. Furthermore, Mr. G. K. Gilbert has observed 
that the old shore-lines about Lake Erie rise to the eastward 
and northward, thus showing that the basins across the old out- 
let have been recently raised. 
same gentleman has also observed that a conspicuous 
terrace south of Lake Ontario rises one hundred and thirty fe 
foes from the western end of the lake to Oneida, Lake, 
cate its eastern end. From this region northward to Adams 
