dah extends between Ghadamez on the west and Augila on the east is
not yet properly ascertained. It seems to be like a broad belt
intercepting the progress of commerce, civilisation, and conquest, from
the shores of the Mediterranean to Central Africa. The kingdom of
Fezzan, however, advances like a promontory beyond it; and then on every
side stretches the desert ocean with its innumerable oases or islands,
which, from being once mere fluctuating names, as it were, on a guess
map, are now by degrees dropping one by one into their right places.

On the breaking-up of the plateau we observed its geological structure
to consist of three principal strata: first, a covering or upper crust,
limestone with flints and red earth; then masses of marl; and then
sandstone, lumps and masses of which were blackened by the contact of
the air with the iron they contain. Under the sandstone was likewise a
bed of yellow clay, with a mixture of gypsum.

The face of the cliffs of the plateau was blackened as with the smoke of
a huge furnace, which gave a majestic and yet gloomy appearance to the
scene as we descended the pass towards the valley of El-Hasee. We found
the plain strewed with great masses of dark sandstone, seeming to have
been detached by some convulsion from the rocky walls, which now rose in
apparently interminable grandeur behind us. We glanced back in awe, and
yet in some triumph, towards the iron-bound desert we had thus safely
traversed; but our eyes soon turned from so bleak a prospect, when we
beheld, dotting the sandy wady, clumps of the wild palm, green copses,
and the majestic ethel-tree.

It was about two in the afternoon when we reached the camping-ground,
all our people shouting, "_Be-Selameh el Hamadah!_" Farewell to the
Hamadah! I cried out the same words in a joyful voice; for, although now
that the dangers of the plateau were overcome they seemed diminished in
my eyes, yet I felt that we had escaped from a most trying march with
wonderful good fortune. It is difficult to convey an idea of the horror
and desolation of so vast a tract of waterless and uninhabited country.
They alone who have breathed the sharp air of its blank nakedness can
appreciate it, or understand how any accidental delay, sickness, the
bursting of the water-skins, the straying of the camels, might produce
incalculable sufferings, and even death. "_Be-Selameh el Hamadah!_"
then, with all my heart. "_Be-Selameh! be-Selameh!_" again rings