Evening journal., 1898-07-07
DEsI1Rrs AND HAlBlTANrs.


persons possessing a more or less in
innate acqnaintanceship with science
who still cherish the belief that deserts
are uninterrupted plains OF smooth
sand, originally deposited at the bot
tom OF the sea, from which they have
been raised at a comparatively recent
epoch. Apart from the difficulty of ac-
counting for the accumulation OF such
vast tracts OF sand on the marine hy-
po,hesis. It viii be noticed, in the
first place, that desert sands are not
stratifsed in the manner characteristic
Of aqueous formations; and, secondly,
even supposing they had been so de-
posted, they would almost certainly
have been washed away, as the land
rose from beneath the sea- Then,
again, we do not meet with marine
shells in the desert sands, of which at
least some traces ought to have been
left had they been marine deposits OF
comparatively modern age. whether
or no the subjacent strata have ever
been beneath the ocean, it Is absolutely
certain that the sands of all the great
deserts of the world have been formed
in stu by the disintegration OF the
solid rocks on which they rest, and
have been blown about and rearranged
by the action of wind alone. All deserts
are situated in districts where the
winds blowing from the oceanic sur
face have to pass over mountains or
extensive tracts OF land, which drain
them more or less completely Of their
load OF moisture. Hence, in the desert
itself, when Of the typical kind, little or
no rain falls, and there Is consequently
no flow ofwater to wash AWAY thedebris
resulting from the action Of the atmos-
phere on the rocks below.
only one degree less incorrect than
the idea Of their submarine origin is
the notion that deserts consist OF un-
broken tracts of sand. 1t is true that
such tracts in certain districts may
extend on every side as far as the eye
can reach, and EVEN much fartehr; but,
sooner or later, ridges and bands of
pebbles, or OF solid rock, will be met
with cropping up among the sand
while frequently, as In the Lybian
desert, there aremountain ranges rising
to a height Of several thousand feet
above the level OF the plain. And II
is these exposed rocks which form the
source whence the sand was, and still
is derived. Such mountains naturally
attract what moisture may remain II
the air, and in their valleys are found
more or less luxuriant vegetation
Gases, too, where the soil is more o.
less clayey, occur in most deserts. an,
it Is in such spots that animal an,
vegetable life attains the maximum de
velopment possible in the heart OF th'
desert. Among the most importan
and extensive deserts OF the world W
have first the great Sahara, with It
approximate area of 10000 squar
, miles, nearly connected with which I
the great desert tract extending
through Arabia, Syria. Mesopotamii
and Persia. BY means OF the more o.
less desert tracts Of Beluohistan, Sin'
and Kuch, this area leads on 70 thV
great Rajputana desert OF India. Nor
important is the vast Cobb desert o
Mongolia, and other parts Of Contra
Asia. In southern Africa there is Oh
great Kalahari desert. In Mort
I America there is a large desert lyini
: east Of the Rocky Mountains, and in
e cluding a great part Of Sonora, Will
e in the southern half Of the New Worl
e there is the desert of Atacama, on th
borders Of Peru and Chile. Lastly, tn
, whole Of the interior of Australia /
! desert Of the most arid and typical de
= scription.
e For sand to accumulate to the depth
] in which it occurs in many parts o
disintegration OF the solid rocks un
: der the action OF atmospheric agencies
] must require an enormous amount O
r time, to be recl1oned- certainly by thou
: sands, and, for all we know, possibl
S by millions. OF years. And we accord
= ingly arrive at the conclusion that tn
larger desert tracts must not only hav
!, existed as land for an incalculabl
= period, but also as desert. Hence W
4 can readily understand why the ami
mails Of Algeria and the rest Of north
d ern Africa differ for the most part fron
d those OF that portion Of the continen
lying to the south of the northeri
" tropic, the Sahara having for ages act
. ed as an impossible barrier to most
i not all. But. II other evidence wer
r requisite, there is another reason whic
T would alone suffice to compel us to re
gard deserts as areas Of great antiquity
The habitabie part of the deserts--an
d 1t is difficult for the inexperienced .
e realize what barren tracts viii sui
. fee for the maintenance Of animal III
+ are the dwelling places of many an