444 
Ittino1s NATuRAL History SURVEY BULLETIN 
Vol. 22, Art. 6 
Fig. 7—The Glacial Lakes Region, which is characterized by abundant vegetation and 
extensive areas of shallow water, furnishes excellent muskrat range. Muskrat houses are built - 
in shallower water than that shown in the photograph. 
habitats. The original marsh has virtually 
disappeared, and most of the bottomland 
timber has been cut or so depleted of den 
trees as to afford little raccoon cover. 
Stripmines are fairly common on the black 
prairie. Muskrats and minks are the chief 
species benefited by the new _ biological 
habitat created by the stripping process in 
mining coal. 
Central Sand Prairie.—With the ex- 
ception that it has more upland sand de- 
posits, fig. 9, this region, fig. 2, is very 
similar to the Northwestern Sand Prairie. 
It contains numerous hardwood timber 
stands on the sand knolls, which afford 
some cover for forest fur animals. The 
whole region is somewhat more rolling 
and is cut by more small stream valleys 
than the Northwestern Sand Prairie. The 
lower Sangamon River valley merges into 
the Illinois River bottoms characterized 
at this point by sizable areas of low, well- 
timbered land. The area is 5,697 square 
miles. Mixed farming, grazing and cattle 
feeding constitute its main agricultural 
activities. 
Gray Prairie.—This southern Illinois 
type constitutes the second largest fur sur- 
vey region, 13,026 square miles in area, 
fig. 2. The gray color of the soil, chiefly 
Fig. 8—Black Prairie habitat type. Thousands of miles of ditches and ditchlike streams 
bordered by corn fields make for high muskrat yields in the Black Prairie Region. 
