p. 4

[4]

rapid accumulation of sand on the north side of it.
At Chicago during five years the accumulation
of sand extended no less than seven hundred
and twenty feet along the pier. As soon as the sand reaches
the end of the pier a bar is formed across the
mouth of the harbor, rendering another "appropriation"
necessary to extend the pier further into the
lake. How far it will be necessary to extend
the pier before the difficulty will cease, is not
It will be when the direction of the shore north of the pier is at right angles with the
direction of the prevailing storms
easily to determined. ^ Figure 3 represents the shore
^at this place in the different years from 1834 to 1839, + is copied
from an official report from the Topographical
Bureau at Washington. Since 1839 no reports have
been made. stated is

The immediate effect of these storms ^as above shown, is
to carry away the base of the steep bank along
the shore, moving carrying the sand and pebbles by
sucsessive [successive] steps towards the south. But the
finer materials,-the soft clays,-are suspended in
the water of the lake causing it to be muddy
for a great distance from the land. The quantity
of matter suspended in the water, & the distance it
is carried out, will of course vary according to
the force and direction of the storm, the configuration
of the coast, the material of the bank acted upon +c.
When the storm abates, the agitation of the
water ceases, and the suspended matter is
thrown down in the form of a thin deposit of
mud on the bottom of the lake. If it falls
in water so sufficiently deep as to be beyond the
influence of the surface waves, it must remain
as a permanent deposit. Another storm produces
another layer, and should it come from a different
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