162 
Ohio Biological Survey 
B. RIVER BLUFFS 
1. Rock bluffs 
The development of rock bluffs along streams was indicated in the 
ravine, where such bluffs are small and relatively short lived. The suc¬ 
cession there is rapid, as it is everywhere along a ravine. The rock 
bluffs along the rivers (the Ohio especially) are not changing so rapidly. 
Their plant succession is slower and exhibits more stages. These bluffs 
are not shaded or protected from wind by the opposite bank of the 
stream, for the valley is too wide. River erosion is the primary cause 
Fig. 32. Under-cut rock bluff on the Miami river at New Baltimore. 
of the existence of the bluffs, but their steepness is renewed in two 
ways—by under-cutting at the foot of the bluff (iig. g 2 ), and by slump¬ 
ing high up on the bluff. 
Almost everywhere a flood plain of greater or less width has been 
built at the foot of the bluff, so that the earliest stages in the develop¬ 
ment of rock bluffs by under-cutting are seldom seen. Such rock bluffs 
are similar to, but much larger than under-cut banks along ravines. The 
