The daily crescent. [volume] ([New Orleans, La.]) 1848-1851, 1850-03-07
Eirhth GeoIogicaI Le cturc.

Prof Forshey commenced by saying that one
of the advantages of the study Of natural science
was, that its subjects always before u.s. We
cannot escape from nature; it is everywhere, and
affords perpetual food for the mind. Let US turn
a few of its leaves and read lesson that will teach
MS what, lies at our own doors.
Louisiana is to the student of Geology, on
large scale, rather limited field, but one of great
interest in many Of its features. IL is divided into
three leading, grand dvisions-Tertiary, Diuvial
and Auvial.
The Tertiary beds occupy about two-fifths Of the
of the State. 1.-THE lecturer here turned to his
diagrams, and exhibited and explained geological
map of the State, which he had attempted to de.
lineate from his own explorations, no one having
ever drawn one before. He begged not to be held
responsible for its detail, but it was approximately
true
The Tertiary lies north of a waving line, COM
mencng on the Sabine near the mouth of the
Neches crossing Red River 20 miles north of
Alexandra, and the Ouachita ten miles north OF
Harrisonburg. It's beds contain Coal (alluminous
brown coal) Salt, Iron, Ochre, Gypsum, and
Marls. The coal inferior to Pttsburg coal,
and would not compete with it in market, but was
worth developing for use in those portions of the
State where the better Goals would not bear the
expense OF transportation. 1t abounded in Sabine,
Natchitoches, Caddo, and DeSoto, and all the par
shes thence east to the Ouachita River. Salt
| Springs were common in Natchitoches and Rap
| des, and had been wrought in earlier times. A
saline bed seemed underle the Tertiary generally.
Iron was found in great quantities in most of the
Tertiary parishes and is well worth the attention
of those who would develop the State resources.
0phra anil ma tha
first in the native form, and the others co-extensiye
with the Tertiary beds. The gypsum was very
| fine, equal to any known to commerce and the
mars very rich, in the regions where they will be
most needed
The Diluyial beds contain little of economical
interest except the Sandstone, which abounds at
| its northern margin These are variously hard
from acrumbng softness to linty quartz hardness.
The whole line of the southern Tertiary and north
ern Drift Tor Diluvia beds) presents hills and cliffs
of these rocks, most Of the quarres furnishing a
very good buildings stone, of cream-whte color.
The harder varieties would answer well for block
/ pavements
| The Atluvial beds occupied about two-ffths 'oi
the State, the delta of the river being about 81
miles wide from about Vicksburg to Bayou Sara
but above and below those points much wider
| 1OWhTuS tnt mouth IL WluenSu out, ana occupied
the whole southern front on the Gulf coast Thi,
Alluvion was the gold mime of Louisiana. 1t wa:
| rescued from the waters by the industry OF man
The lecturer then examined the Mississippi
River-whch, he said he had measured at variou,
points. from the Baze Galena and found it quite
as wide 100 miles up at the mouth. Then The
addition OF four large and many small rivers did
widen it, nor render it more rapid but they deep.
l Il
waters, to deepen its channel. Bear this in
mind. The books tell us that rivers widen by a
certain rule, by increase of entering rivers. The
Mississippi River, probably, was not duly advised
of these formulas, for it had rules of its own The
lecturer had much respect for books, but much
greater respect for truth.
| We were trying to control the river, and keep
the tyrant in bounds. He once usurped the whole
| Alluvion, and yearly kept it under water. Our
barriers were mere child's play as yet. We must
| build greater ones-not higher, but stronger, and
further back-and give to the steamboat
waves, and the abradng power OF increased cur
rents produced by leveeng.
The river did not rise higher now than before
leVees were used This he proved a priori, and
then illustrated by history and observation but
the most powerful proof adduced was, that there
were many Alluvial banks higher than our present
highest waters, and the levees do differ in aver
age height for 800 miles up the river. OF course
the river was once high enough to deposits the
highest Aliuvial grounds Therefore, evees by
contning the water enabled the river to keep open
its channel. Nothing else kept open such a
channel, 100 feet deep ten miles above the S. w
Pass, but the abrasive force, and nothing else could
keep the bars they are, ID to Is feet. Divide
the river by outlets, aud you divide the channel.
making power-you weaken the attack upon the
bars at the mouth, and destroy the rivers havga-
bility. The river belonged to the commerce of the
Valley not to Louisiana. Have care what expe-
riments you try-lor, once divided you never could
| restore it to its channel,