380 
of the “depth to hard bottom’* ran from thirty-six to seventy-two 
inches at stations between Rome and the foot of Main St., Peoria. At 
the Narrows the mud was harder, lighter in color, and was mixed with 
old dead shells and thickly carpeted with sponges and Bryozoa. 
DeptH (oF SortER Mup) To Harp Botrom AT CHANNEL STATIONS 
Ee Station Inches 
180.5 Chillicothe 3 
177.2 One mile below Rome 72 
175.5 Peoria Narrows Hard bottom 
172.3 Opposite Mossville 48 
166.5 One and a half miles above Spring Bay 36 
162.7 Opposite foot Main St. | 36 
The elevation of the bottom of the river channel eighteen miles south 
of Chillicothe, instead of being lower, is actually more than eighteen feet 
higher than the plane of greatest depth opposite Chillicothe; more than 
fourteen feet above the bottom plane of the deepest part of Peoria Lake 
above the Narrows; and more than two feet higher than the highest 
point in the channel bottom between Chillicothe and the foot of the lake. 
I think we must suppose that the way out of Peoria Lake was once much 
more open, and that the action of Farm Creek has been largely re- 
sponsible for building up the high bar that now dams up the entrance 
into the Pekin reach. The nearness to the surface of rock between Pe- 
oria Narrows and Wesley would, however, have prevented in any case 
the excavation of a fast and deep channel through the Chillicothe-Pe- 
oria section. 
Because of the very shallow gradient, and the great expansion of 
the river between Chillicothe and Peoria, the shallower backwater in 
most of the distance, though not separable from the river channel by 
any distinct boundary, resembles more nearly the larger inclosed bottom- 
land lakes than ordinary river littoral. Except for a very short distance 
at and near Peoria Narrows, the land to the eastward of the channel is 
low, the banks are all of mud, and the soft bottom sediments very dark 
in color. Within the 3-foot line on this side the bottom muds contain 
more decayed vegetable matter than further out, and there is a good 
deal of living vegetation (principally Potamogetons and Ceratophyllum) 
during the dry season. On the west side of the channel, sand or gravel 
or hard mud bottom is found for considerable distances out to a depth 
of three to seven feet wherever the channel closely approaches the bluff. 
Opposite Mossville, where the channel is east of the middle of the lake, 
the 1-3- and 4~7-foot zones on the west side are very similar in mid- 
summer to those on the east side first described. Except for a short dis- 
*Made by forcing a 2 X 2-inch pole, square across the end, as deeply into 
the mud as a strong man could with both hands. 
