210.] a region not conterminous with, but almost as large as, the
Mississippi Valley. Of that great, tempering, benign shadow over the
continent, tempering its heat, giving shelter from its cold, restraining
the waters, there is left about 65 per cent in acreage and not more than
one-half the merchantable timber--five hundred million acres gone in a
century and a half. [Footnote: Van Hise, p. 210.]
And as to the land itself--the land first symbolized in the tuft of earth
that St. Lusson lifted toward the sky that day in 1671 at Sault Ste.
Marie, when he took possession of all the land between the seas of the
north and west and south--in the first place, the loss each year from
erosion is six hundred and ten million cubic yards. [Footnote: Van Hise,
p. 307, quoted from W. J. Spillman, "Report National Conservation
Commission," 3:257-262.] This is, of course, inconsiderable in a short
period but in a long period of years means a mighty loss of nourishing
soil. With this loss is that of nitrogen, potassium, and phosphorus,
things of which the farmer had not even heard the names a few years ago.
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