200 The Aniericun Geologist. March, is97 
Disregarding the secondary belts, we find that the main 
lines of drainage, as recorded in the primary belts, had an 
average distance between them of seven miles, although 
sometimes approaching within five miles and again diverging 
to eight miles. The situation of the secondary or branch belts 
has been accurately determined for the Pecatonica system 
only; but, by analogy with these, and relying on an abundance 
of fragmentary evidence gathered in other portions of the dis- 
trict, we may safely assert that tributary streams, as indicated 
by the branch belts, joined the main streams every few miles 
along their course, and at the point of greatest divergence 
were separated from them and from each other by a distance 
of no more than two or three miles. We thus see that the 
geographic distribution of the stratifled sand and gravel in our 
district indicates that the outer portion of the ice-sheet, dur- 
ing the time of their formation, had a very complete system 
of drainage, jjrovided these streams all flowed at the same 
time. 
The Adeline bell. The eastern end of this belt is a short 
distance southeast of the village of Adeline in Ogle county. 
Its direction is at first slightly north of west to a point a few 
miles west of this village, when it turns to a direct west 
course, which it holds for about six miles, until it has passed 
the Illinois Central railroad. Thence it bends to the west- 
southwest, and persists in that direction to the end, not far 
from the Carroll county line. Throughout this distance of 
about twelve miles it is a well-defined ridge, having, however, 
a very uneven crest line. Itma}?^ more properly be described 
as a series of mounds and short ridges standing in a line and 
connected at their bases. Only one short gap occurs, and 
that is where, a few miles east of the railroad noted, a branch 
of Leaf river breaks through the range. The base of the de- 
posit has an average width of several hundred yards, and the 
ridge rises in some peaks to a hight of 110 feet above the 
creek at its base. It trends along the center of a preglacial 
valley, and, with its steep slopes and exceedingly irregular 
crest line, constitutes the most prominent topographic feature 
due to the drift in northwestern Illinois. Throughout the 
greater portion of the range it is clearly composed of only one 
i-idge; but at its eastern end it broadens out and consists of 
