New Orleans daily crescent. [volume] ([New Orleans, La.]) 1851-1866, 1852-08-28
Lake Pontchartrain.

The examination recently made by me of the bottom of
this lake has resulted in proof that it is the lines
anned everywhere firm and reliable for works OF any
character which it may be desired to construct upon it.
There exists it must be confessed possibility that the
rmness indicated by the lead may be but superficial and
that beneath the of shells which nearly the
entire bottom of the lake there may be soft treacher
stratum But this not likely for the following geo.
logical considerations and view of the formation Of the
delta:
The whole delta including the bed of the lake. is formed
| by deposits flom the Mississippi river.
The matter transported by the river is distributed in
this The coarsest particles drted along the
bottom of the channel and deposited its mouth,
forced up the inclined sides of the channel aud left
along the banks wherever the currents lose their velocity
and their consequent ability to transport. These are
chiefly small fragments of slicious rocks The luminous
matters capable of extremely fine communion held
longer in suspension and being nearly of the specific gra
witty of the water carried farther and deposited in
the nearly tranquil currents.
The rivers mouth has never been to the lake
than its present channeotherwise the lake would not
preserve depth equal to the depression at the present
mouth of the river. The material composing its bed
must then be of the aluminous character, which the
waters could transport to distance by very gentle
rents This material is the blue clay which is so well
known for its tenacity and rnness wherever it has had
time become compact 1t is the substratum
| and
| prairics
The trembling prariesn but lake lagoon beds
filled with vegetable matter by gradual encroachment
from the sides Beneath them all (and of them
be ue,y deep lies the blue day The encroachmen upon
the lakes in several localities is going still and at
time not very long hence geoogcally measured, such
lakes Maurcpas Das Alemandes ouacha Cataouacha,
and their bayous, may become trembling praries.
On the north shore of Lake Ponchartran, the duyion
may be and is indeed probable that miles in the
lake the substratum is composed of the clay and sand
alterations that make up that geological formation But
if the foundation is not less reliable for any practical
uses, than if the whole were blue clay.
On the lowest portions of the dft-beds near the lake
we find in many places beds of guathodon shells These
do not belong properly that formation but are an ex-
listing species nhabng the lake in the same Vi
cnity.
This indicates change of relative level of the lake and
that shore by which portion OF the land formerly under
the bracksh water of the lake elevated several
feet above it. We enabled by inspection Of these
and other like beds of sheS to form some idea of the
character of those beds beneath the lake They are sell
dom than two feet thick unless in places where
they have been heaped up by the waves by human
agency
If this is reliable authority the beds will be found to
have similar thickness the bottom of the lake. form
ing band at the surface for the support ofapies
driven through them into the less solid earth beneath
From these considerations have great confidence that
the bottom Of Lake Pontcharran is sufficiently firm for
the support of any work of engineering which the pro-
gressve spirit OF the age and the exgences of our people
may indicate necessary
1t remains to be whether the depth of the water
and the violence of winds and waves are obstacles which
should deter us from undertaking to construct railroad
through the lake avoid the difficulties and the distance
| he ro,ita bjs T
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