399 
3. The 12.0 miles between a point one mile above Beardstown and 
the dam at Lagrange, where the slope of water surface in July, 1901, was 
only 0.10 inch per mile, but the flood velocity (152.04 feet per second 
in March, 1903) greater even than between Havana and Sheldon’s 
Grove. 
DECLINE IN ELEVATION oF Low-WATER SURFACE, 1901; AND FLoop VELOCITY 
Average slope| Flood velocity (av. ft. 
Reach Interval inches per minute, gage, 
miles per mile 18 ft., Peoria) 
Havana to Sheldon’s Grove 17.2 0.62 | 140.91 (17.2 miles) 
Sheldon’s Grove to 1 mile above 
Beardstown 13.3 1.08 | 116.06 (14.3 miles)* 
1 mile above Beardstown to La- 
grange dam 12.0 0.10 | 152.04 (11.0 miles) * 
The principal part of the first subdivision (the 13.8 miles between 
Havana and the foot of Grand Island) as well as the lower 19.5 miles 
of the reach (Browning to the dam), together making more than three 
fourths of the entire reach of 42.5 miles, is comparatively wide and shal- 
low, and has almost entirely sand or sand and shell bottom channel. The 
muds found at the shore stations in 1915 were both lighter in color and 
also less soft and deep than the soft shore deposits found above Havana. 
At the low levels of 1901, depths in the channel between Havana and the 
foot of Grand Island were as a rule 8 to 10 feet and ran at most a little 
over 12; while below Browning they ranged usually between 10 and 12 
feet and for short distances reached 13 to 15. Depths at recent midsum- 
mer low levels have been 2 to 3 feet greater than these. Widths at the 
low water of 1901 of single channel between Havana and the foot of 
Grand Island were mostly 600 to 700 feet, and exceeded 750 feet for 
short stretches; and between Browning and the dam were usually over 
700 feet and for good distances between 800 and 1,000. 
The central section of about 9 miles of channel lying immediately 
above the mouth of the Sangamon River (approximate foot of Grand 
Island to 1 mile above Browning) is much narrower and deeper than 
the stretches of channel above and below it, and has a mud bottom. 
Depths in this section of channel at the 1901 low levels were nearly 
everywhere 15 to 20 feet; while bank to bank width was usually under 
600 feet and fell for good distances under 500. The deep natural pool 
lying above the Sangamon River bar is a homologue of those above the 
great Farm Creek and Havana bars already described, and is of less mo- 
ment biologically, in the respect of furnishing a very rich soil for bottom 
animals, only because the entrance of this large tributary occurs in the 
very midst of a long stretch of river with naturally steep gradient, where 
* Nearest corresponding velocity-reaches (Van Ornum float tests, March, 1903)- 
stop at Beardstown. 
