PIONEER PLANTS 
135 
PIONEER PLANTS ON A NEW LEVEE. 
PRANK E. A. THONE. 
A year ago this spring the city of Des Moines cut a new chan- 
nel and mouth for the Raccoon river, causing it to change its 
course for a distance of about half a mile and to empty into 
the Des Moines river a little more than half that distance be- 
low its old mouth. The bulk of the excavated material was 
piled upon the south bank of the new channel to form a levee 
about fifteen feet high, sixty feet wide at the base, and twelve 
feet wide at the top, with a space of twelve feet intervening 
between the foot of the embankment and the river. The ma- 
terial first excavated, part sand and part a very sandy, silty 
alluvium, was dumped into place by the steam-shovel and 
worked over into permanent shape by grading shovels; the 
material from the bottom of the cut, practically pure sand, was 
dumped on the opposite bank and left there in long, irregular 
heaps. The western end of the levee was also left more or less 
unshapen, and is in consequence some six or seven feet higher 
than the rest of the embankment; it also has a larger propor- 
tion of sand in its makeup than the levee proper, though it 
is not so nearly pure sand as the heaps on the opposite bank. 
Fig. 3. — ^Diagram of area studied. Heavy lines indicate bridges. 
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