THE CLYDE SERIES OF SOILS. 43 
from 10 to 15 tons per acre, onions 400 to 700 bushels per acre, while 
potatoes, which are also grown to a small extent, give yields from 150 
to 250 bushels per acre. An excellent field of cabbage, grown on the 
Clyde clay loam, is shown in Plate III, figure 2. 
Elsewhere the Clyde clay loam, where appearing in small areas 
scattered through other soil types, is either tilled to the general farm 
crops or, where occurring in larger areas, is utilized mainly for 
pastures. 
CLYDE CLAY. 
Next to the Clyde loam the Clyde clay is the most extensively de- 
veloped soil type of the series. It has been encountered in eight 
different soil-survey areas, located in New York, Ohio, Indiana, Illi- 
nois, and Michigan. A total area of 319,424 aeres has been mapped, 
of which considerably more than one-half is found in the scil sur- 
vey of the Toledo area, Ohio, where 165,056 acres occur. It is prob- 
able that other large areas will be encountered in the Maumee basin 
and in the area of glacial Lake Saginaw, not yet covered by soil 
surveys. 
The surface soil of the Clyde clay, wherever it has been encoun- 
tered, is characteristically a dark-gray, drab, or nearly black clay 
loam. It is well filled with organic matter to a depth of 8 or 10 
inches, and this renders the surface soil considerably more friable 
and easily worked than would ordinarily be the case with material of 
such fine texture. There is usually a strong tendency toward granu- 
lation of the surface soil, due to the high amount of organic matter 
contained and to the fact that both the soil and subsoil are some- 
what calcareous. The subsoil to a depth in excess of 36 inches is a 
lighter gray, drab, or mottled yellow and gray clay. It is dense and 
sticky when wet, but becomes intersected with numerous joints and 
crevices when properly drained and exposed to the action of the 
atmosphere. It frequently contains gravel, the quantity varying 
from a few scattered pebbles to a considerable percentage of the soil 
mass. Neither the soil nor the subsoil contain any considerable 
number of stones of larger size. In other cases it is free from any 
trace of gravel and stone and consists of laminated or massive lake 
clay. In the former instance it is probable that the type constitutes 
merely a thin surface veneering of glacial lake or swamp material 
over the underlying till or water-laid glacial deposits. In the latter 
it is a true glacial-lake deposit. 
In all cases the surface soil gives the distinctive evidences, through 
the color and the accumulation of organic matter, of the swampy con- 
dition under which it was formed. 
It is a common characteristic of the Clyde clay, possibly more 
general than with other soils of the series, that the subsoil contains 
