SECIION ERO MSs) MISSISSIPPI, RIMES LO SPOUND GAP. ay 
hills. A slight examination will also show that on Keokuk 
limestone white oak extends to seventy-three per cent. of 
the total height of the hills; on Conglomerate sandstone, to 
seventy-one per cent.; on coal-measures, to fifty-seven per 
Pent.; on silicious limestone, to fifty per cent.; and on St. 
Louis limestone, to forty per cent. This indicates that Keo- 
kuk, leaving out the Keokuk shales, is the richest of the 
formations in white oak growth. 
In the same way it may be shown, from the general tables, 
that liriodendron extends to an average of forty-five per cent. 
of the total heights of hills, or not quite half way. The reader 
can easily make deductions for all other timbers. It will be 
noticed that there is no general and definite relation exist- 
ing between the height of hills and the height to which any 
particular timber will grow. Everything depends upon the 
nature of the hill, and upon whether the formation is adapted 
to retaining moisture. On a damp hill, though very high, a 
timber will be found, growing entirely to the top, which would 
not extend more than a few feet up another and drier hill. 
It is exceedingly interesting, 
height above drainage to which the principal forest trees 
extend; and that can be deduced from the tables given. 
though, to know the average 
SUMMARY. 
A brief review of the foregoing pages will show— 
first. That changes in geological formation will produce 
immediate, and often exceedingly marked, effects upon the 
character of the timbers. Such changes are often noticed, in 
shallow-rooted timbers, before a change of formation is reached, 
owing to the effect of detritus from the neighboring formation. 
They may likewise be noticed in very deep-rooted timbers, for 
the opposite reason, that their roots extend down beneath the 
surface formation, and penetrate the underlying one, when 
that is not visible. “ 
Second. That height above drainage always produces a 
marked effect upon timbers, whatever the formation ; but that 
such effect is less in the case of a Keokuk limestone formation 
than in any other found in Kentucky. 
TIM. I.—15 225 
