506 
Buell—Boivlder Trains. 
appears in the northwest corner of Kane county, near the Mc¬ 
Henry county line, being overlapped by the formations of the 
latest drift which here push out beyond its margin. 
It has been already noted that the old morainic border, 
which bears the marginal distribution of the southwestward 
train in southern Dane, northwestern Rock, and the northeast 
corner of Green, overlies the kame ridges which appear in 
Rock and Winnebago counties, as the marginal deposits of the 
southwestward glacial movement. As this belt itself disap¬ 
pears beneath the Kettle moraine in the center of Union town¬ 
ship, Rock county, it is impossible to correlate it with any of 
the succeeding morainic belts that cross the area west of Janes¬ 
ville, and we have the choice of two hypotheses, either that the 
quartzite bearing ridge is a northwestward continuation of one 
of the inner belts that cross the center of Rock county, or that it 
is a correlative of the later and more distant Shelbyville moraine. 
In the former case the belts are separated by an overlap of ten 
or twelve miles. In the latter case, their interval of separation 
is about 75 miles. 
These investigations furnish no data for the determination of 
this question, and it is immaterial to our present purpose to do 
so, as the drift movement which effected this marginal distribu¬ 
tion, even if synchronous with that producing the Shelbyville 
moraine, must have followed the same lines as that effecting the 
earlier morainic deposits of Rock and Winnebago counties. 
In the latter case we would have not four but five bowlder 
trains, the third and fourth so closely overlapping as to be in¬ 
distinguishable. 
TIME RATIOS. 
The time ratios indicated by the condition of the bowlder ma¬ 
terial in the successive trains show a very wide lapse between 
the earliest and latest depositions. The weathered condition of 
the material in the westward train as compared with that ob¬ 
served in the drift section south of the Portland ledges denotes 
a ratio greater even than ten to one. This interval appears to 
be divided rather unequally by the succeeding episodes, the 
material found on the area of the southward trains showing 
