Washington standard. [volume] (Olympia, Wash. Territory) 1860-1921, 1882-11-10
The Libyan Desert.

A closer study of the geological struc-
ture of the Libyan Desert Is likely to
change the views prev ouslv entertained
regarding its origin. Prof. Z!ttrl. in q
lecture delivered in Munich, sand that
the scientific expeditions to that re-
gion. undertaken by RohfS, Zittel.
Ascherson, and Jordan, have yielded
81 paving harvest in geology at least.
We learn that this region, the geo.-
ogy Of which was 50 li,tle under
stood. as well as the So-calied Arabian
Desert, which lies between the Nile and
the coast of the Red sea, and which is
inseparable from the Libyan Desert 50
far AS the qualifications are concerned,
is not, as has been generally supposed,
the remains of a sea that has recently
disappeared. On the contrary, il con-
ssks of a formation that belonged to
the cretaceous and lower tertiary, form
atioas long anterior TO the geological
present. The rocks of the cretaceOUS,
which prevails, are principally sand
stones. variegated mari. Calcerous mari,
and limestone; the cretaceous fauna
was found to be extraordinarily richly
represented, as rarely happens else
where, such as oyster, ammonite, sea
urchins, etc. In the oldest tertiary the
nunlmulites formed deposits, SO called
because the petrifactions which they
held were considered bv the common
people to be petriiied coins. There are
shells of foramlnfera from the size of u
pea to that of Il dollar, and elsewhere
in the lowest layers of the tertiary they
appear in immense masses. The soil
of the desert is covered with them for
miles.
With the exception that in the middle
tertiary the sea pressed inward on the
north in two comparatively mimpor-
tant depressions. every trace ii any
later sea is wanting.
The whole Sahara as well as the Lib
yam seems to belong. for the greater
part, to the chalk formation, and while
the older strotsfed rocks are wanting
eruptive rocks appear, forming noun
tain chains.
Hence there can be no talk of the
sea having covered the Sahara in the
recent past, for if this were the case
there would be later stratilied rocks on
top of the cretaceous with fossils re-
sembling the marine fauna of the pres
ent time. Then, too, the surface of the
desert is not of such shape as to in-
dictate that it has been the bottom of the
sea; but, on the contrary, the torn,
ragged, assured chasms of the desert
mountains. the deep cut valleys, indi-
Bale the erosive action of flowing waters
which, perhaps in the Oldest historic
times still lent luxuriant fertility to the
region now so sterile. This sterile
character of the Sahara is to be attrib-
uted entirely to the unfavorable mete-
geological conditions, to the almost to-
tai lack of rain. The soil itself is well
adapted to the production of rich
vegetation.
The quantity of salt present in the
collections of water rendering many OF
the GASES uninhabtable, depends upon
the rock salt, which, with gypsum, is
very abundant in the chalk mari as well
as elsewhere. The ascending thermal
waters, which make a paradise in the
midst of the cherries desert, according
to ZittePs investigations, are not, as
was formerly supposed, referable to the
zones of Central Africa, whence they
are led northward on impenetrable
strata that have an Inclination in that
direction.
The sand of the desert is from the
"Nubian sandstone" which belongs to
the cretaceous and extends along the
left bank of the Nile through the
tenth degree of longitude. 1t has been
transported hence by ancient water
courses, aided by the wind.-Sciei,tits
american.