deposit of diluvial detritus which lies between the cultivation and the
mountains on the west bank of the Nile opposite Luxor. Many of these are
of the same type as those found on the surface of the mountain plateau
which lies at the head of the great _wadi_ of the Tombs of the Kings,
while the diluvial deposit is at its mouth. The stuff of which the
detritus is composed evidently came originally from the high plateau,
and was washed down, with the flints, in ancient times.

This is quite conceivable, but how is it that the flints left behind
on the plateau remain on the original ancient surface? How is it
conceivable that if (on the old theory) these plateaus were in
Palæolithic days clothed with forest, the Palæolithic flints could even
in a single instance remain undisturbed from Palæolithic times to the
present day, when the forest in which they were made and the forest soil
on which they reposed have entirely disappeared? If there were woods and
forests On the heights, it would seem impossible that we should find,
as we do, Palæolithic implements lying in situ on the desert surface,
around the actual manufactories where they were made. Yet if the
constant rainfall and the vegetation of the Libyan desert area in
Palæolithic days is all a myth (as it most probably is), how came the
embedded palaeoliths, found by Gen. Pitt-Rivers, in the bed of diluvial
detritus which is apparently _débris_ from the plateau brought down by
the Palæolithic _wadi_ streams?

Water erosion has certainly formed the Theban _wadis_. But this water
erosion was probably not that which would be the result of perennial
streams flowing down from wooded heights, but of torrents like those
of to-day, which fill the _wadis_ once in three years or so after heavy
rain, but repeated at much closer intervals. We may in fact suppose
just so much difference in meteorological conditions as would make it