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Ohio Biological Survey 
Ian), it will be shown, affect the character of vegetation, because of their 
different physical natures. 
The Eden shale is made up of compact thinly bedded shales inter¬ 
rupted at intervals of about ten feet by thin limestone layers. This 
material is easily eroded and weathers rapidly. Consequently slopes on 
it are gentle except in the immediate proximity of the stream, where 
active erosion produces a gorge. The altitude of its upper surface varies 
from over 700 to less than 600 feet within the area considered, owing to 
the dip of the strata. This variation in altitude of outcrop has consid¬ 
erable effect upon stream profile and ravine slopes, and through these, 
upon the vegetation. 
The Maysville is made up of alternating thin-bedded shale and lime¬ 
stone layers. The frequent occurrence of limestone layers makes this 
formation much more resistant than the underlying Eden shale. Only 
one division of it (the Bellevue) outcrops except where relatively rapid 
erosion is in process. The Maysville, however, weathers so much more 
slowly than the Eden shale, that it produces noticeably steeper hillsides 
where removed from the influence of actively eroding streams. And 
it is resistant enough to withstand extremely rapid stream cutting, so 
that valleys in it are less gorge-like than those in the Eden shale. 
The lower formations, Utica and Pt. Pleasant, are usually covered 
by the thick alluvium which fills the valleys to a depth of 100 to 200 feet 
(fig. 2 ). Along the larger streams—especially, the Little Miami and 
Miami above New Baltimore—the broad flood plains are a conspicuous 
feature of the topography. The flood plains along the Ohio and lower 
Fig. 1. View from edge of upland above South Milford, showing the flood 
plain of East Fork and Little Miami rivers, the terrace upon which Terrace 
Park is situated, and the level sky line of the uplands beyond. 
