THE FERN BULLETIN 



105 



The middle third is somewhat more diversified. The 

 eastern half is a broad rolling plain, with no promin- 

 ent hills nor any very deep valleys. The streams in 

 places run over the surface of the plain, and in places 

 are slightly intrenched in it. In the western half of the 

 middle third the streams are more deeply intrenched; 

 the Wabash and some of its tributaries, as Sugar 

 Creek, Pine Creek and others, have cut gorges 300 to 

 400 feet deep along parts of their courses. Some por- 

 tions of White River and its tributaries are similarly 

 intrenched. 



The southern third or more of the State is much 

 more diversified. The area is more deeply trenched by 

 the streams, so much so that in places lower secondary 

 plains have been formed, and the underlying rocks have 

 stamped their character on the surface. As the strata 

 have a low west and southwest dip, the more durable 

 rocks form cuestas or sloping plateaus, with steep es- 

 carpments to the east on their outcropping edges, and 

 long plains sloping gently to the west on the bedded 

 surface. Between these escarpments are irregular plain 

 areas on the softer strata. Newsom cites three of these 

 cuestas and three lowland areas, the broadest one of 

 which is on the west of the outcrop of the Coal 

 Measures strata. 



The upland sloping plateaus are in many places very 

 much dissected and diversified by the numerous deep 

 valleys cut in them, so that they form a mass of irregu- 

 lar hills. The area in most places along the outcrop of 

 the Mansfield sandstone is very much broken, and along 

 the eastern margin of the outcrop, where the sandstone 

 caps the hills, the latter are high, steep and marked by 

 many perpendicular cliffs and steep talus slopes. This 

 belt of cliffs and gorg-es is markedly different from the 

 Knobstone area further east which extends through 



