St. Tammany farmer. [volume] (Covington, La.) 1874-current, 1888-09-15
THE GREAT LAa<g&

l. ~ $40
(eelAgisa1 Hlse1eysG1 1AAas Rssu.ss3oa asI
Change h fheis Lsvsl.,
: Remising that lakes arc desdo5Sd
by rivers. byi<he double process ei
6ln1G tAa0 - sswish sediment and
Of 6eepening - oAaansi - escape.
ard that, oAihe sGhss hand. lakes at.e
formed chiefly b ~ uphc1sal a ~
earthso sygfa0e and BY its erosion by
the movements Of glasiszsasse author
dsvotes the glsatar. part Of his Srscia
70 the ,gea0gic history Of tha formar
| ton of the great lakes. Their beds.
with tho possible, exception. Of Erie.
were sSoured out Of solid y rock by
the great glaciers of the ios age. but
accumulation Of debris in many cases
increase their depth aud influence the
direction Of their outflow. The removal
OF this debris. in the case Of the
Erie. for instance. would reduce it
greatly. perhaps entirely drain il. and
would make it flow into Ontario and
Hamilton. The increase OF heat caused
the edge Of The great glacier to retract
from the southern border ut Fort
Wayne. where the water generated
upon it flowed into the Wabash. and
separated Erie and Ontario into two
lakes. But rs long a. the ice remained
In the st. Lawrence valley the waters
found their escape into the Mohawk at
Rome. One of the beaches formed BY
the action Of the waves has its crest
marked BY the ridge road from Lewis
ton to S0dus. At this time Lake Erie
was only one-third ~ long ~ now. and
its surface was only one-fifth as great.
Toledo. Cleveland and the Bass Islands
being far inland. When Lake Ontario
forced = new output through the St
Lawrence valley its level was drawn
down five hundred feet and its area
reduced ninety per cent, becom-
ing thirty per cent. smaller than
at present. The rising Of the
depressed land to the northward gave
tho lakes their present dimensions, and
the oscillation then received q check.
"A further fitting Of the land to the ex-
tent Of three inches In each mile would
send ? great river from Chlcago to the
Mississippi. reverse the current in the
Detroit. stop Niagara Falls and rob
tbs s1ppef ST. lawrence Of seven
eiehte Of It's 'watee." Whether, con-
trary tQ Ehas appsas 70 Be- law against
absolute stability. the oscillation hAs
ceased or not, il il now 20
slOw as to prevent the detection OF any
movement, the present levsl eof the
water having nDmaissd nearly con-
slant for many centuries. . -:
Other changes are, however, in
progress from the action Of the rivera
Tho St Clair is feebly securing its
channel and building its delta; the Nj
agsrs is eating it, way back to Lake
Erie; the St Marie, Desroit and St.
Lawrence are despenine their chan.
nels. ,"Al these processes are too
slow to Affect our hopes and fears con-
,erning the immediate eature. and for
'ur -posterity in the ysar $1,000 We
nave NO solicitud& The mon who
hall watch the draining Of Lake
:rie-or Who. pershance. shall And IL
worth their while TO prevent t1-will
. far surpass US in powers and TO
ources as We surpass the mea Who
satched the lakes creation. For all
PRACTICAL purposes our inland seas are
and their bssins stable.
rhe only qualifications that affect our II
ore those wrought BY the
raves upon,thsir eeast"c The changes
. the wates levels that ars nesieeA are
ue TO the variations in the, rainfall |
pom The lakes themselves and upon h
he. land drained W tlSs streams That
our. into then. Ths smount Of r4in-
All varies from year to year and
rOm one season to another in the
ame year. and the level Of the
'saer ooscillasss around an, average | .
ositioa- sthat., rsnalns~ hxed. Thns
uring the period -irOn 1850 - 1851.
he mean average range. of Lake
RE was 'L6 feet, and the extreme !
ange for tl1e same period S.5 ieet. In
sSS Lake Erie rose 10 inches shove its q
rdinary high stagA and IN 1878 IL fell Z
feet below its usual plane. Tho
resent low water Is the sequel of last {
immer's drought" the lake region I
Aving received only about 25 inches OF Z
.infall instead Of its usual IS inches. q
his should cause fall Of the lakes OF !
bout IA inches. half from direct loss I
I'd half from the loss Of the streams
lat empty into them. But the average Z
II Of al the lakes was only about z !
lches, owing probably to tho GOODNESS
the autumn. which retarded evapo-
'tion. In Lake Superior the fall was
inches below the average low stage,
le lowest point reached In seventeen {
.ars. except on two occasions In ,
RE it was 2 inches below the average. 4
These variations relate to the entire Z
rfaees Of the lake. A part Of one I
" b depressed and another part ,
Used by . gale especially in tho
se Of Lake Eric. On account Of it, !
allowness. A gale has been known
raise the level Of one Of it, ends
ven or eight feet and to depress the
her to an equal amount Differences !
atmospheric pressures also effect
fferent parts Of the same lake. The
pid change Of air pressure. as in the
- q toruadoes, sometimes causes (
'ythnio pndulations = high - tho
rGest created by the wind. Thseo are
% tides which are p. regular q on I
9 oceGn. but'the highest spring tide
~ oaAy about three inches, While
. average height 70 probably sol I
ore than = inch.-C. X. 01bsse 10