152 
IOWA ACADEMY OF SCIENCE Voi,. XXVII, 1920 
level or show a slight decrease. This might easily be the case 
in view of the character of the precipitation, which was in the 
form of showers of short duration, and further in view of the 
fact that just previous to this period the open soils showed a 
content equal to or very near the minimum reached for the season. 
Since these soils also show a finer texture they might be expected 
Fig. 30. Soil moisture content in per cent of air-dry soil for middle of timbered 
and open slopes — stations Ib and XI, respectively. For amount of rainfall see 
note, fig. 29. 
to be more retentive of moisture, and any light precipitation would 
be apt to make itself more manifest here than in the timber soils, 
which latter may exhibit a more rapid permeability but showed 
more nearly a normal content before the showers occurred. It 
is important to observe here, however, that the content of the 
open soils does not reach that of the timber soils. 
Following the rains which fell from July 30 to August 6, all the 
soils at the top of the timbered slope show a fluctuation with a 
decided rise in the surface soil. The rainfall was evidently suf- 
