529 
*Marshall. Saratoga Lake region one mile north of Camp Grove. 
Another small area 6 miles east of Lacon. Mostly swamp, some upland 
prairie. 
Mercer. Flood-plain along the Mississippi River. 
Ogle. Small tract one mile east of Polo. W. E. Eikenberry. 
Peoria. Lowlands along the Illinois River. 
Randolph. Flood-plain along Mississippi and Kaskaskia rivers. 
*Richland. Fox Prairie, 5 miles west of Olney. Cemetery at Noble. 
Rock Island. Flood-plain along Mississippi River. 
Washington. Flood-plain along Kaskaskia River. 
White. Small tracts in Enfield and Hawthorn townships. 
Whiteside. Prairie between Albany and Erie. 
Winnebago. Small tracts along Rock River. 
All of the above counties and the remaining counties with the ex- 
ception of those in the southernmost part of the state were reported to 
have patches of virgin prairie along railway rights-of-way, old line-fences, 
and roadways. Owing to a difference in farming methods these latter 
relics are somewhat more abundant in the southern half of the state 
than elsewhere. Numerous relics along most of the principal railways 
of the state and along hundreds of old line-fences were seen during the 
survey. 
This brief summary of present conditions shows that there are still 
several thousand acres of virgin prairie in the state which have been so 
little disturbed by man that they are of considerable value for ecological 
studies. The data also show that the greater area of these relic tracts 
are on flood-plains, swampy regions, and sand. Outside of the sand 
prairie the upland prairies are limited to small tracts, fence-rows, and 
railway rights-of-way, the latter of which were considered only after 
the survey had advanced sufficiently to indicate their limitations. 
ORIGIN OF THE Prarrie HaBitats 
The various plant habitats of the state are correlated with its recent 
geological history. The accompanying glacial and soil map after Leverett 
(18) and Hopkins (15) shows that nearly all of the state has been gla- 
ciated. The glaciers left the state with a gently rolling topography. 
The depressions, resulting from the formation of moraines across pre- 
glacial valleys and the unequal deposition of the glacial drift, became 
postglacial lakes and sloughs which were slowly drained. In general 
the moraines became forested, but many of the lakes and sloughs through 
gradual filling and draining became prairies, a process which was far 
from complete when the farmer entered the state and established arti- 
ficial drainage systems. The extensive areas and long duration of the 
wilderness of sloughs and swamps in the Wisconsin glaciation is best 
attested today by the depth and extent of the rich humus soil that accu- 
mulated in them. Their estimated dimensions are not lessened by the 
stories of the early settlers who swam their horses across them in early 
