has placed the habitat of the makers and users of these implements.

The idea was that in Palaeolithic days, contemporary with the Glacial
Age of Northern Europe and America, the climate of Egypt was entirely
different from that of later times and of to-day. Instead of dry desert,
the mountain plateaus bordering the Nile valley were supposed to have
been then covered with forest, through which flowed countless streams
to feed the river below. It was suggested that remains of these streams
were to be seen in the side ravines, or wadis, of the Nile valley, which
run up from the low desert on the river level into the hills on either
hand. These wadis undoubtedly show extensive traces of strong water
action; they curve and twist as the streams found their easiest way
to the level through the softer strata, they are heaped up with great
water-worn boulders, they are hollowed out where waterfalls once fell.
They have the appearance of dry watercourses, exactly what any mountain
burns would be were the water-supply suddenly cut off for ever, the
climate altered from rainy to eternal sun-glare, and every plant and
tree blasted, never to grow again. Acting on the supposition that this
idea was a correct one, most observers have concluded that the climate
of Egypt in remote periods was very different from the dry, rainless one
now obtaining. To provide the water for the wadi streams, heavy
rainfall and forests are desiderated. They were easily supplied, on the
hypothesis. Forests clothed the mountain plateaus, heavy rains fell, and
the water rushed down to the Nile, carving out the great watercourses
which remain to this day, bearing testimony to the truth. And the
flints, which the Palaeolithic inhabitants of the plateau-forests made
and used, still lie on the now treeless and sun-baked desert surface.

[Illustration: 007.jpg THE BED OF AN ANCIENT WATERCOURSE IN THE WADIYÊN,
THEBES.]