August, 1955 
stretches of bluff frontage, totaling 25 to 
30 miles, remain hill prairie or are in part 
hill prairie. Possibly as much as three 
times this extent, 75 to 90 miles, or about 
one-eighth of the bluff frontage on the 
east sides of the major stream valleys, was 
prairie in the early nineteenth century, but 
was converted to pasture or otherwise dis- 
turbed by the activities of man. The bases 
for such an estimation are the few scat- 
tered prairie plants along stretches of 
bluffs now occupied principally by blue- 
grass and numerous pasture weeds. Such 
stretches of bluffs are common along the 
Mississippi River in Jo Daviess County. 
Doubtless these bluffs were prairie cov- 
ered in the not distant past. 
Hill prairies have been surprisingly 
successful in resisting destruction by the 
grazing of domestic animals and by some 
of the activities of man. ‘There are no 
records to show how heavily these prairies 
were grazed by bison before the arrival of 
white men in Illinois. It is possible that 
bison grazed many hill prairies, but that 
they failed to reach some that were hid- 
den by surrounding dense forest. Whether 
or not pastured hill prairies observed for 
this report are being reduced by overpas- 
turing is not yet evident. Goat pasturing 
in one site along the bluffs of the Illinois 
River south of Rosedale caused complete 
destruction of the prairie, leaving only 
bare loess on the slope. The spread of 
residential and industrial areas has de- 
stroyed some of the hill prairies. On the 
other hand, it is evident that fire has not 
destroyed them; seemingly, it has per- 
mitted an earlier and more tender growth 
of grass. 
What is the probability that hill prairies 
are now being invaded by forests? Some 
of the most typical hill prairies are located 
on brow slopes where the cliffs are so high 
that they extend above the trees that grow 
on the toe slopes; without the shade of 
the trees, the brow slopes, especially those 
facing southwest, are exposed to the heat 
of the sun and to the prevailing winds of 
summer and are thus too xeric for growth 
of mesophytic forest and will probably 
remain prairie. The bluff coves, which 
serve as drainageways on the slopes, are 
more mesic and, in places, support mixed 
forest. Such forested coves contain tree 
Evers: Hitt Prairies or ILLINOIS 395 
species that are found in the forests of the 
basal slopes, of the slopes of the tributary 
valleys parallel to the main valleys, or of 
the uplands. Where the bluffs are low, or 
in the few places where the ascent from 
floodplain to upland is continuously of 
low gradient, trees have long shaded the 
upper slopes and greatly reduced wind 
movement. In such situations, forests 
have been established over entire slopes. 
In years of abundant rainfall, forest 
seedlings become established on_ prairie 
spurs, only to die in years of less abun- 
dant rainfall or in periods of successive 
dry years, as of the 1930’s. Dwarfed 
trees, as well as dead sumacs and red ce- 
dars, are reminders of dry years and a 
contest between forest and prairie. It 
thus seems probable that a shifting equi- 
librium was long ago reached between 
prairie and forest, especially on bluffs 
with high cliffs. As long as the present 
topography and climate persist, such hill 
prairies will remain approximately as they 
are. 
Delimitation and description of the 
actual stages of succession within hill prai- 
rie areas cannot be made now, but must 
await the advent of interested botanists 
of the future. In the interim, it is im- 
portant that botanists continue the study 
of these sites and publish the results of 
their studies. From such studies, bota- 
nists will be able to trace actual, not hypo- 
thetical, paths of succession and also de- 
duce with a greater amount of accuracy 
the past vegetational history. 
ANNOTATED LIST OF HILL 
PRAIRIES 
The following list of Illinois hill prai- 
ries includes only those prairies which the 
writer visited during the field work for 
this study. The name given to each of 
the prairies was derived from one of sev- 
eral sources—the name of the landowner, 
or of the tenant, or of the farm on which 
the prairie was found; the name of that 
stretch of bluff occupied by the prairie; 
or the name of some nearby landmark or 
community as applied locally or found on 
a quadrangle of the United States Geo- 
logical Survey topographic map. Loca- 
tion of each prairie is given according to 
