189 
VOLUME OF THE ANCIENT WABASH RIVER. 
Won. A. McBETu. 
The Wabash valley at Terre Haute has a width of five to six miles. One- 
third this width has a depth of approximately one hundred feet, embracing 
a flood plain tract through which the river meanders in a channel averaging 
one thousand feet wide and, twenty feet deep. The remaining half is a terrace 
about half the depth of the deeper part. The whole valley bottom shows the 
effects of stream deposition, the pre-glacial trench of two hundred to two 
hundred and fifty feet in depth being half-full of sand and gravel. A point 
Jenerzlized profile across Wabash Valley of Terre Haute. 
of interest in connection with the stream and valley is the question of volume 
of water by which various phases of the work was done. The size and weight 
of pebbles in the gravel indicate a volume and velocity much greater than 
that of the present stream either in average volume or flood. Some suggestion 
as to the width and depth of the stream at its stage of greatest flow is furn- 
ished by features of the terrace surface consisting of sandbars and delta 
deposits. This terrace surface is marked with numerous shallow current 
lines or channels. The bars form ridges of greater length than width, often 
many times longer. They trend northeast, southwest, the direction of the 
valley and have the characteristic stratified structure of such features, the 
layers of finer or coarser sand dipping steeply down stream. Extensive 
areas of the terrace surface lie at an elevation of four hundred and ninety 
feet a.t.l. Some places are five feet lower while some of the ridge tops rise 
to the five hundred and thirty foot level. Low water in the present stream 
is four hundred and forty-five feet. Points in sections 3, 23 and 24 and a 
bluff side delta of a brook crossed by Fruitridge avenue at the south edge 
of Section 24, Town 12 N. Range 9 W., rise to nearly the five hundred thirty 
foot level. Sandbars and deltas are built under water and the surface of the 
stream in which these deposits were made must have been a few inches 
and possibly several feet above the ridge and delta tops when they were 
