i'()2 The American Geologist, March, is97 
moPt of which stands in the center of the valley, while the 
most southern one partly rests on the slope of a rock ridge. 
These four ridges are parallel and about 1,000 feet apart. 
They end abruptly at the western end, where they are being 
eroded by Yellow creek and the Peeatonica river; excepting 
that the southern one is continued southwestward b}'^ a heavy 
deposit, which, however, shows subdued drift contours. 
The belt has now left the valley of the Peeatonica river 
and henceforth occupies the preglacial valley of Yellow creek, 
which it has so obstructed as to turn the stream into a new 
course for eight miles. . Several small parallel ridges continue 
the belt to its next heavy development, three miles southwest 
of Freeport. Here we find a roughly circular series of mounds 
and ridges apparently embossed on the eastern slope of a 
ridge, which resembles a rock ridge, but crosses the old Yel- 
low creek valley at a right angle. Well sections show it to be 
composed of drift, partly till. Just east of this ridge the 
main belt of stratified drift is joined by a well marked sec- 
ondary belt, which comes down from the east over an upland 
country averaging 125 feet above the valley bottom of Yellow 
creek. Near the same place a narrow belt apparently di- 
verges from the main belt and trends northwest and then 
nearly due north. Its length is about three miles, and it is 
marked by a line of cone-shaped knolls and short ridges, 
which is crossed in going westward from Freeport at the dis- 
tance of about two miles from the city. Its trend is anom- 
alous, for it is apparently at right angles to all the other 
belts of the region. 
On the western slope of the ridge crossing the ancient val- 
ley of Yellow creek, the main belt is continued by several 
parallel broad ridges, evidently containing much material but 
displaying no decided drift topography. These ridges cul- 
minate south and southwest of the village of Bolton in the 
most prominent accumulation of stratified drift of the Peea- 
tonica belt. It covers at least 1,000 acres and rises into steep- 
sided parallel ridges attaining a maximum hight of perhaps 
100 feet above the adjoining lowlands. This finely developed 
deposit dies away to the west into what appears to be a sand 
plain, but which lies mostly below the present creek level and 
cannot well be studied. Northwestward occasional sand ridges 
