average yield of crops per acre is greater
where the ice has done its work. Where the country rock consists of
limestone, which naturally forms a rich soil, the difference in favor
of the glaciated area amounts to only 1 or 2 per cent. Where the country
rock is sandy, the soil is so much improved by a mixture of fertilizing
limestone or even of clay and other materials that the average yield
of crops per acre in the glaciated areas is a third larger than in the
driftless. Taking everything into consideration it appears that the
ancient glaciation of Wisconsin increases the present agricultural
output by from 20 to 40 per cent. Upwards of 10,000,000 acres of
glaciated land have already been developed in the most populous parts of
the State. If the average value of all products on this area is reckoned
at $15 per acre and if the increased value of agricultural products due
to glaciation amounts to 30 per cent, then the net value of glaciation
per year to the farmers of Wisconsin is $45,000,000. This means about
$300 for each farmer in the glaciated area.

* R. H. Whitbeck, "Economic Aspects of Glaciation in Wisconsin",
in "Annals of the Association of American Geographers," vol. III in
(1913), pp. 62-67.

Wisconsin is by no means unique. In Ohio, for instance, there is also
a driftless area. * It lies in the southeast along the Ohio River. The
difference in the value of the farm land there and in the glaciated
region is extraordinary. In the driftless area the average value per
acre in 1910 was less than $24, while in the glaciated area it was
nearly $64. Year by year the proportion of the population of the State
in the unglaciated area is steadily decreasing. The difference between
the two parts of the State is not due to the underlying rock structure
or to the rainfall except to a slight degree. Some of the difference is
due to the fact that important cities such as Cleveland and Toledo lie
on the fertile level strip of land along the lake shore, but this strip
itself, as well as the lake, owes much of its character to glaciation.
It appears, therefore, that in Ohio, perhaps even more than in
Wisconsin, man prospers most in the parts where the ice has done its
work.

* William H. Hess, "The Influence of Glaciation in Ohio," in
"Bulletin of the Geographical Society of Philadelphia," vol. XV (1917),
pp. 19-42.

We have taken Wisconsin and Ohio as examples, but the effect of
glaciation in those States