FORESTRY SURVEY 267 



In Sections 10 and 11 the occurrence of the more re- 

 sistant limestone causes a narrowing of the stream valley 

 and the almost complete disappearance of the alluvial 

 flood plain. The floor of the valley is rocky and irregular 

 and while not cultivated is stripped of most of its timber. 

 Small bur oaks, cottonwood and sumach, with smaller num- 

 bers of the species named above form an open scrubby 

 cover, the size of the trees increasing upon the slopes. 



Upon the upland in Section 11 the forest passes into an 

 open oak pastures with trees 1 to 20 inches in diameter. 

 Portions of the valley and upland are known as "Matthew- 

 son Park" and have been used to some extent as a picnic 

 gi'ound. The rugged topography unfits this area for culti- 

 vation, but the limestone cliffs and rocks and the open 

 forest could find no more fitting function than that of 

 providing a pleasure resort for the adjacent city. 



In Section 13 the portions north of the old Illinois and 

 Michigan Canal are mostly covered with the remains of 

 an oak forest, which extends northward into Section 12 

 along two small streams. The river bluff and slopes of 

 the ravines have the usual mixed type in which oaks pre- 

 dominate. The red-bud, (Cercis catiadensis)^ and the hack- 

 berry, (Celtis occidentalis), are common especially near the 

 triangulation point, while upon the edge of the canal wil- 

 lows are frequent. An open oak forest, well grazed, oc- 

 cupies the more level upland in which are found in addition 

 to the usual white, red. and bur oaks specimens of black 

 oak (Q. vdutina). Hill's black oak, (Q. elUpsoidalis) and 

 shingle oak, (Q. imhricaria). The more open areas show 

 sumach, service berry, bush honeysuckle (DicrviUa) Xew 

 Jersey tea (Ceanothits) and a prickly pear cactus (Opun- 

 tia). ' 



Any critical study of the vegetation of the flood plain 

 of the Illinois Eiver must be reserved for a future report, 

 but it may be noted that upon the north side of the stream 

 the forest growth consists only of a few patches of rather 

 small black willows, one such patch of some two acres 

 lying east of Split Eock just south of the canal. A larger 

 area where willows are mingled with river maple occurs 

 along the railroads just north of Oglesby. The total area 

 of this stream side forest within the township does not 

 exceed 50 acres. 



