194 Proceedings of Indiana Academy of Science. 
light-colored clay land or the Miami series, while the depressed areas 
with poor drainage, or no drainage, in swamp or marsh conditions, 
become the black or brown areas known as the Clyde series; or, where 
there was a great abundance of partly decomposed organic matter, they 
become Muck. The Dunkirk comprises the sand ridges and the loamy 
sand of a light yellowish brown color. 
Alluvial Soils.—The alluvial soils of Cass County are the sediments 
deposited in the stream valleys by flood waters. A loam in the humid 
region always has a very luxuriant growth of vegetation where it has 
an adequate supply of water. 
One of the effects of the presence of humus is to produce granules, 
forming a mellow, easily worked soil. Where a soil is cultivated without 
adding to the supply of humus, the soil becomes more compact and runs 
together, producing decreasing crops and reducing the moisture- 
retaining capacity. Cultivation loosens the soil, promoting aeration, 
and increases the amount of available plant food. 
Chemical Properties—A chemical analysis of a soil will show the 
amounts of the different plant foods, such as nitrogen, phosphorus, 
potassium, calcium, etc.; but the difficulty is that it does not even give 
a hint as to the form in which the elements occur in the soil. The 
analysis shows correctly the total organic carbon, but as a rule this 
represents about one-half the organic matter, so that 20,000 pounds of 
organic carbon in the upper six inches of an acre represent but twenty 
tons of organic matter. But this twenty tons is largely in the form of 
old organic residues that have accumulated during the centuries because 
they were so resistant to decay; so two tons of clover plowed under as ° 
a green manure would have greater power to liberate plant food for a 
growing crop than all the twenty tons of old residue of organic remains. 
The sediments came from the uplands adjacent to the valleys of the 
different streams, and a certain kind of upland gave rise to a different 
type of alluvial soil. The overflow land is placed in the Genesee series. 
The Fox series consists of terrace soils, deposited perhaps by the glacial 
waters, which were a great deal more abundant than the waters of the 
present time. The meadow land has not been mapped, but much of the 
land along the smaller streams, classed as Genesee, belongs to this type. 
MIAMI SILT LOAM. 
Characteristics.—The Miami silt loam consists of a dark gray or a 
light brown friable silt loam having an average depth of ten inches. 
It is usually deeper in depressed or level areas and somewhat shallower 
on the crest of ridges and on steep slopes. When moist the surface 
becomes almost uniformly grayish or yellowish brown, but when dry it 
becomes a light ashy gray. 
