2 BULLETIN 142, U. S. DEPARTMENT OF AGRICULTURE. 
The soils of the Miami series do not occupy all the territory within 
which they are developed. In addition to these soils, and closely 
associated with them in the lower peninsula of Michigan and in 
portions of central Wisconsin, are those of the Coloma series. The 
latter are distinguished by light-brown to gray surface soils, yellow 
or reddish subsoils, and by their derivation from noncalcareous ma- 
terials. They are prevailingly more gravelly and sandy than the 
soils of the Miami series. 
Throughout all of the more nearly level areas occupied by the 
Miami soils there are large and small areas of soils which have dark- 
gray or nearly black surface soils and gray, drab or mottled sub- 
soils. These soils are classed in the Clyde series, and are distin- 
guished by the large quantities of organic matter which have accu- 
mulated in the surface soil. They occupy areas in which obstructed 
drainage gave rise to small ponds, or to swamps. They occur in 
the depressions and level areas lying between the low swells and 
ridges occupied by soils of the Miami series. 
Toward the western boundary of the Miami series these soils are 
associated with dark-brown or black soils, which are classed as the 
Carrington series. Originally the Carrington soils were mainly 
prairie. They are of glacial origin, and usually calcareous in the 
subsoils, but are distinctly and uniformly much darker in color 
than the soils of the Miami group. 
In nearly every area in which the soils of the Miami series are 
encountered there are also found extensive areas of water-worked 
and stratified soils of glacial origin which were deposited either as 
terraces along streams issuing from the melting ice or in the form 
of nearly level outwash plains of varying size. Several different 
series of soils have thus been formed. They are all distinguishable 
from the soils of the Miami series through the presence of stratified 
beds of sand and gravel at or near the surface and through the pre- 
dominance of gravelly and sandy soils. 
GEOGRAPHICAL DISTRIBUTION. 
The soils of the Miami series occur most extensively in the west- 
ern part of Ohio, the central and northeastern part of Indiana, in 
southern Michigan, south of a line connecting Bad Axe and Muske- 
gon, in the Traverse Bay region of Michigan, in extreme north- 
eastern Illinois, throughout eastern Wisconsin, and in a portion of 
the upper peninsula of Michigan, adjoining Green Bay. The loca- 
tion of the Miami series of soils is shown in figure 1. 
The eastern boundary of the region dominated by the soils of the 
Miami series extends southward from the vicinity of Timn, Ohio, 
