158 ILLINOIS STATE ACADEMY OF SCIENCE 



As well as may be ascertained today the original areas 

 of woodland, about 1840 and for an indefinite period before 

 then, were approximately as represented on the map issued 

 by the County Superintendent of Schools about 1900. The 

 singular fact that these wooded areas should remain about 

 the same in extent for over half a century is said to be 

 explained as follows. During the years 1840 to 1900 the 

 nature of the woods underwent great change at the hands of 

 the whites. During this time a haphazard selection cutting 

 rather than actual clearing is what prevailed, desirable spe- 

 cies of trees of large size being cut out promiscuously. From 

 about 1880 to 1900 actual clear cutting was more notably 

 under way, but this was of such a degree that it did not be- 

 come strikingly noticeable until about 1900. From this date 

 onward, however, the clearing became great until very 

 recent years, along with further selection cutting, the latter 

 still going on. Today Ogle County has over 30,000 in- 

 habitants. About 57c of the land in the neighborhood of 

 the Rock may be estimated as wooded. A recent estima- 

 tion for the northwestern part of Illinois of 8% may serve 

 for rough comparison. 



THE VEGETATION 



The Rock would probably be referred to as a prairie river 

 located in the grasslands (prairie) — deciduous forest tran- 

 sition area of North America. This transition belt, as is 

 well known, possesses characteristics, in the species of 

 plants present, of the deciduous forest area to the east- 

 ward and of the grasslands to the westward. The prairie 

 areas of this transition belt comprise the major part. Its 

 affinity with the east is expressed in the woodlands along 

 streams and extending out irregularly from these. Al- 

 though Ogle County lies in this transition a more exact 

 delimitation of ecological boundaries takes note of what is 

 known to plant geographers as the prairie peninsula. This 

 is an arm of grassland extending eastward into Illinois 

 and adjacent states. It grazes Ogle County at the south. 



Further, while the above statement holds good in a gen- 

 eral way, the Rock River woodlands are not thoroughly typ- 

 ical of the prairie river. In some respects they are more 

 representative of the eastern portion of the transition belt. 



