Year: 1859

/
especially at the time of the spring
freshets. These bottom-lands are al.
most always heavily timbered and
with a great variety of trees, among
which the elm, linden, black walnut,
white and burr oak, poplar and ash
are the most common with a great
number of others, forming. especially
in the valley Of the Mississippi, for
est which can hardly be rivalled il
the variety of species and vigor o.
their growth. The breadth of the riv
er bottom is very variable along the
last.named river, it frequently expands
to six or eight miles, while, in other
places, there is hardly more than room
for the stream itself to pass between
the bluffs. Generally, the width of
the valley is proportioned to the size
OF the stream SO that, on the smaller
tributaries, there is but narrow belt
OF low land, within which the stream
meanders, with a very crooked course,
crossing and recrossing from one side
OF the valley to the other. On the
tributaries of the Mississippi there are
but few traces of terraces in the river
valleys; while on the great river itself
there are, in portions of it's course, in
dlcations of two distinct stages of ele-
walton. More usually, however, even
on the Mississippi, we rise from the
river bottom up to the foot of the bluffs
by gradual ascent, without steps or
| hn nf hn nI
eating an uninterrupted and gradual
drainage, rather than one interrupted
by epochs of repose.


The river bottoms are not always
timbered. In the Mississippi valley,
there are newly-formed islands and
patches of land, often Of considerable
extent, which have not as yet been
covered with vegetation, owing to
their too recent formation ; but which
will, in process of time, as we may
suppose, support as dense. growth
of timber as any other part of the
bottom, unless the capricious stream
shall again sweep them away, before
sufficient time has elapsed for them
to become covered with soil, by the
growth and decay Of vegetable mat
ter and the deposition of river mud
Besides these temporarily bare patch
es, there are strips of land along the
Mississippi of considerable extent,
just above the level of the highest
rise of the river, which are called
prairies, and are indeed destitute of
trees, although quite different in char
actcr from the highlands to which that
name is usually applied. Prairie la
Cross, Prairie du Chen, Prairie la
Porte the site of the town of Guten-
berg, the site of Cassvillc and other
strips of land, especially on the left
bank OF the river, as far down as Du-
buque, belong to this class of prairies.
Prairie du Chen for instance, which
has given its name to rapidly-grow-
ing town, is belt of land extending
from the junction of the Wisconsin
river north for six or eight miles, and
having width of from one to one
and half miles. 1t slopes gradually
upwards from the river, and has an
elevation of about thirty feet above
the usual stage Of water The soil is
dark reddish-brown sand, with lay
ers Of small pebbles. Back of this
strip of unwooded plain, the bluffs
rise almost perpendicularly to the
height of nearly 400 feet. Sometimes
the edge of the prairie adjacent to
the river is more elevated than that
portion which is nearest to the bluffs,
as at Prairie la Porte, for instance,
where the river, at its highest stage,
almost surrounds the town and con-
verts the plain into an island.


The soil of all these low prairies is
almost pure silicious, somewhat fer
ruginous, sand, very different from
that Of the high prairies, although in
both cases characterized by the abb
sence of trees. The cause of this
popularity seems to be the combined
influence of an extremely sandy soil
with the proximity of the river, which,
under the peculiar climatological re-
lations Of the northwest, exposes it to
extremes Of moisture and dryness, un-
suitable to the growth of arborcal
vegetation. Where the soil is more
clayey, or not made up so exclusively
of sand, there seems to be no obstacle
to the most vigorous growth of forest
trees.