GREENE COUNTY. 683 
sand, clay, and vegetable mold. The whole substance of the soil is 
honey-combed by their agencies and rendered vastly more permeable to 
airand water. Tothem, indeed, the fineness and homogeneity of the sur- 
face are largely due. Whoever thinks this agency an insignificant one 
has but to examine carefully the surface of any square rod of ground in 
early summer to be convinced of his mistake. Such an examination 
will show to any one who has eyes to see that an enormous amount of 
mechanical labor, most useful in its results to man, is being performed by 
these despised insects. The porosity of the ground, which is partly due 
to these agencies, is illustrated in the well known fact that the earth 
taken out from an excavation will never fill the space from which it has 
been removed. But the porosity that nature gives to soils is not pro- 
ducedinaday. It is the result of these seemingly insignificant agencies 
extended through periods of time sufficiently long. 
This stratum of soil, thus prepared, is the sole dependence of the brick- 
kilns which are possible in almost every square mile of the surface of 
the county, and from it brick of excellent quality are cheaply produced. 
Mention has thus far been made of the formation of soils from the 
bowlder clay alone, but processes precisely similar to those already de- 
scribed, only far more rapid in their action, are going on in the beds of 
modified or stratified Drift which make so important an element in the 
surface of the county. The opening of every gravel bank shows these 
processes with the greatest distinctness. The solution of the limestone 
pebbles has been carried on for one or two feet below the surface until 
most of them have entirely disappeared, the only pebbles that remain 
being the hard and stubborn greenstones and granites of northern origin. 
Vegetable mold has been mingled with these weathering products to 
the same depth to which the solution has advanced, and thus the 
boundary line between the soil and what it covers is marked by color as 
well as texture. The incipient stages of the solution of limestone peb- 
bles can be seen below this boundary in the softened and corroded sur- 
faces which they show, but the mass below is, after all, a gravel bank 
and not soil. 
(b.) Varieties. The soils of the county may be divided into the follow- 
ing classes, which will be readily recognized by those familiar with the 
area under consideration: 
1. The valley soils, consisting principally of the first and second bot- 
tom lands. 
2. The soils formed from the high level gravels. 
&. The yellow and white clays, the common upland soils of the county. 
4, The black uplands or blue grass land, most largely shown in Ross, 
