CROP REGIONS OF OHIO 



47 



streams has left many steep slopes and deep valleys. The leveling 

 action of the streams, that is, the lowering of the hills and filling 

 of the valleys has been slight as compared with the leveling in the 



^ PERMIAN PENNSYLVANIAN MISSISSI PPIAN^ DEVONIAN SILURIAN ORDOVICIAN 



CARBONIFEROUS 



Scale 

 O 10 20 30 40 soMilci 



Fig. 9. Geologic map of Ohio. From the geologic map of North America in U. S. Geol. 

 Survey Prof. Paper 71. 



glaciated sections of the state, where the deposits of till have filled 

 and blocked many of the valleys. On the steep slopes subject to 

 rapid erosion, good soil is not formed unless the plant cover is left 



