'Southern Nejd: Journey to Kharj, Aflaj, Sulaiyyil, and Wadi Dawasir in 1918.' [‎39v] (83/100)

The first of these sections comprises a strip of the Tuwaiq
plateau barely twelve miles in length from south to north, but
extending over its whole breadth from the western rim to the
eastern plain. Bounded on the north by Wadi A seasonal or intermittent watercourse, or the valley in which it flows. Birk, it contains
two imposing ravines running across the whole breadth 'of the
plateau, namely, Shaib Ahmara to the south and Shaib Tilha
on the north, both of which as we have seen run down into the
Halfawi and so into the Ajaimi.
Following the Nadh Baaija for three miles northward we
entered Shaib Ahmara, which, coming down from the west
in a valley about a quarter of a mile broad between cliffs of from
fifty to seventy feet high, turns to the north and runs in that
direction some three and a half miles until the single well of
Baaija is reached—a fine well with an inexhaustible supply of
water at a depth of fifteen fathoms, round which in a wide
bulge of the valley was a most imposing collection of some
fifty or more black tents of various sizes belonging mostly to
the Qubabina and partly to the Shakara (A1 Hasan).
From the Baaija well the Shaib resumes its easterly (with
slight tendency to north) course, which we followed the next
day for some five miles to its point of exit to the plains, into
which we emerged for a brief run of four miles along the low
eastern extremity of Tuwaiq. At this point we crossed the
shallow bed of Shaib Tilha not far from the point where it issues
from the ravine in which it descends across the plateau. We
now turned due north still along the outer slope of Tuwaiq
but soon found ourselves entering a wide bay into the latter,
forming as it were, a miniature delta for Wadi A seasonal or intermittent watercourse, or the valley in which it flows. Birk, whose
actual mouth we reached four miles beyond the point at which
we crossed the Tilha. The channel of the Birk at this point is
about a quarter of a mile or rather more across but its containing
banks are of no great height though it is said, probably truly,
that further up the channel runs between precipices of tre
mendous height.
The configuration of the drainage system at this point is
extraordinarily interesting and at first sight a little puzzling.
Wadi A seasonal or intermittent watercourse, or the valley in which it flows. Birk comes down from the west into the bay just mentioned
down which it runs due south for a short distance before turning
north-east to join the Ajaimi; the opposite side of the bay
opens out into a wide channel, which at first sight seems to be
either a branch or a tributary of the Birk; in point of fact it is