176 
Ohio Biological Survey 
A slope of 30 or 40 degrees may be covered with a second growth 
mesophytic forest. The direction of slope must be northerly—northeast, 
north, northwest, or rarely east or west. The soil must be deep, and of 
such a nature that it retains water. These requirements are met along 
a number of ravines, which cut in deep glacial deposits composed largely 
of fine sand and silt. A single clearing formation changes from a xero- 
mesophytic forest association on the south slope to a mesophytic one on 
west and northwest exposures of equal steepness. The succession passes 
from an association in which locust and sumach (Rhus typhina) are domi¬ 
nant among the trees, to one in which beech, sugar maple, and tulip are 
most abundant. Very few species are common to the two associations. 
With the locust and sumach of the south slope are red elm, hackberry, 
and mulberry. Blackberry thickets form a lower layer in this open forest, 
and on the ground are a few herbs among which are Venus’s looking-glass 
(Specularia perfoliata), wild pansy (Viola RahnesquU), the ebony spleen- 
wort (Asplenium platyneuron), and some Cystopteris fragilis. On the 
west and northwest slopes, with the beech, maple, and tulip, are dogwood, 
sweet buckeye, iron wood, a few large chestnut and red oaks, and bass¬ 
wood. The herbaceous flora is not that of a climax forest, but is remark¬ 
ably different from that of the south slope. Here Cystopteris fragilis 
is common, and with it are the maidenhair fern (Adiantum pedatum), 
Jack-in-the-pulpit (Arisacma triphyllum), bloodroot (Sanguinaria cana¬ 
densis), May apple (Podophyllum peltatum), black snakeroot (Cimicifuga 
racemosa), and Solomon’s seal (Polygonatum hidorum). 
Later stages in the clearing succession are very similar to corre¬ 
sponding associations of the original succession. 
D. THE EROSION CLIMAX EOREST 
The mesophytic forest which is found upon a number of the gentler 
or more protected slopes, it has been shown, differs from that of the 
uplands. It contains a larger variety of trees, and its herbaceous growth 
is extremely rich and varied (dgs. 28 , 2 ^). The relatively simple life 
history of the upland forest is not found here. Topographic changes 
have played an important part in the succession. Retrogressive periods 
must have had some place in it. This is the mesophytic forest which 
develops at the end of a long and varied succession. It is the climax 
of every erosion succession now in progress, and as the forces of erosion 
must sooner or later modify all areas, it may be considered as the prob¬ 
able climax forest of the region. In contrast to the pre-erosion climax 
