440, Inrtinois NATURAL History SURVEY BULLETIN Vol. 227 Arie 
region for this area measuring only 821 boundary along the Mississippi River is of 
square miles, fig. 2. The terrain is rolling rugged limestone bluffs. ‘Che thick lime- 
to broken, figs. 5 and 25. The western stone formation here has impeded the de- 
Ve : 
NS 
ISN 
SISXXRN NINES 
on COCU00 CUS Ot 
RS oR Mo 
; o 
COO, C5 q 
| ? 6S, eet, i“ KKOD x 
2 
COCEES 
AFOSR RRR OA 
PEASE PIL RRP ROOK 
YOUN Tara ees 
ORR SRR ORR 
KOK SMP eases eee. O60s eee 
ay 
IS LEE IOS OSPR HELD 
(7 PIR RRR KKK KOS 
BLACK PRAIRIE 
GLACIAL LAKES 
NORTHWESTERN SAND PRAIRIE 
WESTERN PRAIRIE 
CENTRAL SAND PRAIRIE 
GRAY PRAIRIE 
RIVER BLUFFS AND BOTTOMS 
RANDOLPAY CK KKK x2 
Wuaeec seat ont 
| QO RORY 
| SSEKPLS AP 
ZN 
NEUAN BOE 
Fig. 2—Map of Illinois showing the eight regions into which the state was divided for the 
purpose of making the fur resource survey. ‘The River Bluffs and Bottoms Region is the only 
one that is not continuous. 
