148 
IOWA ACADEMY OF SCIENCE Voi.. XXVII, 1920 
no significance in connection with the forest as a conservator of 
moisture, and that both moisture of the air and of the soil will 
be conserved by protection against evaporation, which may be 
accomplished by topography or by groves. 
Area and Site Descriptions for Soie Moisture Studies 
The area on which the present studies were made comprises 
the hillsides and banks bordering both sides of the Maquoketa 
river near its headwaters. Lying in a section of the state which 
has not been glaciated for a long time, it has drainage fairly well 
established. The stream in this section depends for its regular 
flow largely upon underground waters which come out as springs 
all along both banks of the river. Part of these emerge from 
the immediate borders of the stream, while others break forth 
at considerable distances from the banks. The soils of which 
the tests were made are for the most part sandy, especially in the 
surface and subsurface layers, and the movement of water in them 
is apt to be well defined. 
In choosing the sites an attempt was made to have the soil 
layers as nearly similar as possible, and also, to have the slopes 
nearly alike in elevation, degree of slope and exposure, so that 
the run-off in all directions would be approximately uniform 
except as checked by absorption into the soil. A study of table 
A shows, however, that the soils on the open slope are apt to con- 
tain less sand than those for the timbered slope, especially in the 
subsoil layer. 
Methods 
Soil moisture determinations were made for stations on open 
and timbered slopes as follows : 
Timbered site; Station II, top of slope; station Ib, middle of slope; 
station la, foot of slope. 
Open site: Station X, top of slope; station XI, middle of slope; 
station XII, foot of slope. 
Soil samples were taken at these stations at three day intervals 
for depths as follows: surface (0 to 7 inches), subsurface (7 to 
20 inches), and subsoil (20 to 36 inches). These samples were 
immediately placed in screw-cap containers and taken to camp 
where the moisture content was determined. This was calculated 
in per cent of air-dry soil. 
Care was taken to have the various soil borings at each station 
not closer than six feet. The top of each hole was filled with a 
grass plug and mulched over. Thus the borings already made 
