260 Wisconsin Academy of Sciences, Arts and Letters. 
The bowlder groups noted by Strong were both of them al¬ 
together ont of the path of true valley glaciers. One was 
“on the ridge between the Strickland and Myers branches” 
headwater streams of an eastern affluent of Fever Fiver. Ho 
sandstone is shown on this affluent and hut a small ex¬ 
panse on the main stream. If they were glacially transported 
we are virtually forced to the conclusion that they have crossed 
a divide from some other valley. 
The other, a few miles west of south from Dodgeville, is on 
an upland where a glacier must have moved up the Pecatonica 
to have reached it. As a glacial deposit it's probable source 
would he somewhere on the opposite, or Wisconsin slope of the 
main divide. 
We are therefore forced to conclude that if there was glacia¬ 
tion it was of a thoroughly confluent type and on a scale so 
extensive that the Wisconsin Valley was filled to the point of 
overflow. 
It would indeed be a physical impossibility that snow fields 
should form on the divide of sufficient volume to feed a south¬ 
ward flowing ice sheet twenty to twenty-five miles long without 
involving the Wisconsin Valley. 1 
The fact that the problem is thus extensive must needs in¬ 
spire great caution in the interpretation of isolated features. 
Contrasting strongly with the all-embracing ice cap as above 
outlined, the glaciation of the central area so far as the depos¬ 
its give us an idea as to their extent, was by strictly valley 
glaciers of no great length, and not fed from common snow 
fields unless the vicinity of Tomah should he a partial excep¬ 
tion. 
The depth and steepness of the valleys would make them ad¬ 
mirable receptacles for wind-drifted snow. The balance of 
probability is in favor of their having been filled by such de¬ 
posits unless precipitation in the driftless region was practi¬ 
cally nil. Hot all of such deposits could have developed glacial 
motion, perhaps only a small part, hut there are situations in 
i In working out the above relationship the writer has made use of 
the excellent topographic sheets of the lead region. 
