The weekly union record., 1865-02-04
A Sea Turned into a Desert.

We are familiar through the Bible with
Instances of dry land covered with water bat
many OF our readers may nei have heard hih-
erto that the desert oi the Great Sahara. in
the North OF Africa. wss once a sea. The
reasons for this theory are thus civeu in the
opening (ihe july number Of the new Geolog-
cal Magazine in translation from 4 paper
by F.. Desor, Of Nenfchatel. Switzerland
"lf the Sahara is the bottom Of 4 vanished
sea il is Interesting 10 inquire il this disappear
ance has been caused by sudden Gpheaval or
by gradual and successive elevations and at
what epoch this extraordinary phenomenon has
changed the aspect Of the African couiincn'.
and consequently produced the serious mciif
cations Of the climate Of Europe There was
geDeral impression that the Desert of the
Sahara was Of recent formation; but the opin.
ions of the geologists were divided as TO the
period 10 which il should be assigned, some
considering it Of Tertiary and Others Of Quar-
ternary age Our observations resolve these
doubts, and definitely fix the age of the Sahara
by the help of little shell, the CGr9ius ,f,Sls.
This shell was shown TO exist IN the neigabor-
hood Of the Caravanserai Of Om ThIour, near
Cho,t Melrir, aud il had been found at depth
of about tweniy-three feet in the arteslsn wells
of that place From this it might have been
supposed that it belonged 10 the Chol, ,or
lake, Melrir. But, on the other, me. along
with il was q species OF Bsccinum from stage
to stage, al great distance from the Chott
(even near Guenmar in Sout). away in the
same geological position, in bed OF sand dis.
I tinctly s;ratifed underneath the superficial
gypsum. 1, thus became evident tha; the
shells did not belong TO the Cho,t, bat TO
lower stratum. indicating a sea far more eNien-
siye and older than the salt lakes. These
shells therefore. not eply aties, existence Of y
sea in those regions but also that the sea be-
louged TO our own epoch Further, the Cardufg
edile is, in the Mediterranean, a species Inhab-
| iting brackish waters at the mouths OF rivers,
and we may conclude that the Sahara, before
being dried up, was an inland sea-a kind OF
brackiSh Bsltic-and this. amongst other
things, explains the small uumber OF thel
species for il is known that the iaunas oi M
lano seas are poor in number and debased.
40 sum up: when oil communication With
the ocean had ceased, and the gull became a,
lake, the saltness of the waters would. byI
evaporation, increase so much as almost III
destroy animal life the Chott Melrir would
become like the Dead Sea and, IN fact Il 4
affirmed that il is completely destitute OF LIE
This idea of slow but recent elevation 10 thsi
SaDaIa Dau aNtauN oCeu uuVltu - - AuN"tyI
/ by Mr. Escher, and il was q source OF lively
satisfaction to him TO fud bis hypothesis conf
tirmed on the spot. The presence of the sea,
was referred to BY Escher TO explain ceriaiu,
phenomena 10 Switzerland connected with thal
Glacial period, which ended when the sea dis
appeared Is it possible TO form an idea u
climatic conditions imposed on Europe by this
vast extent of water? We may do so When
we consider the influence exercised by the
burning winds which come from the sahara,
and which are so Justly called snow eaters and
glacial destroyers.' While the Sahara was
covered with water, the Swiss mountains nevea
felt the burning breath Of the frhu and the
'sirocco;' the Winters, never opposed by 4
lukewarm breeze, could accumulate their snow
and their ice, and extend the borders Of iheii
empire But when the desert was dry, what
an effect must have been produced by the hrs |
visit of the 'frbn to the enormous glaciers u
the Alps What torrents What delugcs II
water. What ravages, especially on tht|
southern slope and how easy to comprehend
the erosion OF the mountains and the levelingI
of the plain of Lombardy, subjected TO thest
rude assaults, and covered with erratic debris.