The Geography of the Region about Devil's Lake and the Dalles of the Wisconsin: With Some Notes on Its Surface GeologySalisbury, Rollin D.
Science
The Geography of the Region about Devil's Lake and the Dalles of the Wisconsin: With Some Notes on Its Surface Geology
Salisbury, Rollin D.
Physical geography; Wisconsin -- Description and travel
In the Devil's lake region isolated and well-defined kames are not of
common occurrence. There are, however, at many points hills which have
something of a kame-like character. There is such a hill a mile
southeast of the Court house at Baraboo, at the point marked p, Plate
XXXVII. In this hill there are good exposures which show its structure.
There are many hillocks of a general kame-like habit associated with the
terminal moraine south of the main quartzite range, and north of the
Wisconsin river. Many of them occur somewhat within the terminal moraine
a few miles northwest of Merrimac.
_B. Beyond the edge of the ice, on land._--As the waters escaping from
the ice flowed farther, deposits of stratified drift were made quite
beyond the edge of the ice. The forms assumed by such deposits are
various, and depended on various conditions. Where the waters issuing
from the edge of the ice found themselves concentrated in valleys, and
where they possessed sufficient load, and not too great velocity, they
aggraded the valleys through which they flowed, developing fluvial
plains of gravel and sand, which often extended far beyond the ice. Such
fluvial plains of gravel and sand constitute the _valley trains_ which
extend beyond the unstratified glacial drift in many of the valleys of
the United States. They are found especially in the valleys leading out
from the stouter terminal moraines of late glacial age. From these
moraines, the more extensive valley trains take their origin, thus
emphasizing the fact that they are deposits made by water beyond a
stationary ice margin. Valley trains have all the characteristics of
alluvial plains built by rapid waters carrying heavy loads of detritus.
Now and then their surfaces present slight variations from planeness,
but they are minor. Like all plains of similar origin they decline
gradually, and with diminishing gradient, down stream. They are of
coarser material near their sources, and of finer material farther away.
Valley trains constitute a distinct topographic as well as genetic type.
A perfect example of a valley train does not occur within the region
here discussed. There is such a train starting at the moraine where it
crosses the Wisconsin river above Prairie du Sac, and extending down
that valley to the Mississippi, but at its head this valley train is
wide and has the appearance of an overwash plain, rather than a valley
train. Farther from the moraine, however, it narrows, and assumes the
normal characteristics of a valley train. It is the gravel and sand of
this formation which underlies Sauk Prairie, and its topographic
continuation to the westward.
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