Glacial Lake Nicolet. — Upham. in 
county, or at least that the waters of the period did. Nowhere north 
of this was it observed at a height exceeding 330 feet above lake Mich- 
igan. Near Chilton it reaches an elevation of 372 feet ; north of Stock- 
bridge, 358 feet; south. 390; in section 6, Marshfield, 401 feet; in section 
5, Taycheedah (T. 15, R. 23), 315 feet. These have been selected from 
a large number of observations, either because more reliable, or be- 
cause more significant, on account of their positions. .... It will be 
observed that the formation rises gradually from its southern extremity 
to the region of lake Winnebago, beyond which it declines. On lake 
Superior an analogous clay rises at least one or two hundred feet 
higher. 
Aside from the general northward depression indicated by these 
facts, a special flexure seems to have taken place in the region of lake 
Winnebago, either of the nature of a greater depression during the 
time of deposit, or of a greater elevation subsequently. This fact is 
entirely in harmony with the concurrent indications of several peculiar 
features in the underlying formations and general structure of the 
region. It is on the basis of this general northward depression, and on 
the sequence of the formations, that this and the associated deposits are 
referred to the Champlain period. 
When Warren and Chamberlin thus described the region 
of the Fox river, lake Winnebago, and Green bay, the effect 
of the barrier of the waning continental ice-sheet to form lakes 
in basins sloping northerly toward the receding ice border had 
m it been fully and generally recognized. Neither of these 
writers appealed to the glacial barrier on the north as the 
cause of the formerly greater lakes which they mapped and 
described ; nor did Chamberlin refer to the southward outlet 
at Portage, near the head of the Fox valley, but rather as- 
cribed this entire lacustrine tract to an expansion of lake Mich- 
igan when the lake Winnebago region was much depressed 
below its present altitude. 
Portage and the Fox river basin were covered by the Green 
Kay lobe of the ice-sheet during its moraine-forming Wiscon- 
sin stage, and the recession of the western side of this ice lobe 
piobably began somewhat earlier, and uncovered the formerly 
ice-enveloped country somewhat faster, than the concurrent 
recession of the southern part of the Lake Michigan ice lobe, 
which lay upon the area of the glacial lake Chicago. The two 
outlets, however, at Portage and at Chicago, doubtless began 
to discharge the waters of glacier-dammed lakes on the north 
and northeast at nearly the same time; and each of these lakes 
existed independently of each other until the continued glacial 
