"نجد الجنوبية: رحلة إلى الخرج والأفلاج والسليل ووادي الدواسر في سنة ١٩١٨." [و‎‎٣‎٣] (١٠٠/٧٠)

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of Northern Tuwaiq the horizon was bounded by the clear-cut
line of the southern escarpment: all else was Tuwaiq, the broad
barrier of Northern Tuwaiq lying between plain and plain
and furrowed internally by countless ravines cleaving the
plateau into a jumble of ridges.
From this point on until we reached Riyadh our course lay,
with but few and unimportant breaks towards the end of the
journey, along the broad back of Tuwaiq, whose plateau, sloping
gently, so far as my observations are reliable, from north to
south and from west to east, and averaging some twenty-five
to thirty miles in breadth, falls for geographical purposes from
south to north into four well-marked divisions, namely
(1) The catchment area of Wadi Dawasir.
(2) The catchment area of the Maqran.
(3) The hill district of Aflaj.
(4) The catchment area of the Sahaba.
The first of these divisions, on which we now r entered,
extends some forty miles from the northern border of the
Sulaiyyil basin northwards and about twenty miles from wesi
to east, comprising for the most part a ragged jumble of ravines
and ridges running down from both sides towards the central
depression of the Maragha Majma valley. On the east of this
tract lies the well-marked ridge bordering the Hamam trough,
while between its western edge and the outer rim of the Tuwaiq
escarpment lies a thin strip of typical bare plateau meiging
imperceptibly, as it extends southward, in the lumpy ravine
track. Our course now lay northward for about seven miles
over the latter across or past the heads of a number of unim
portant Shaibs which run down into the two main channels
of Kumah and Wara and so into the Sulaiyyil basin. We were
now close up to the edge of the western escarpment whence our
course ran diagonally north-east across the plateau strip to the
edge of the ravine tract along which we followed NNE. up to
the watershed, a distance of rather less than thirty miles. The
plateau generally sloped south-eastward travel sed by little
runnels concentrating at certain points to form the heads of
a number of bold ravines which ran down in a uniform south-east
direction to join the Maragha. The first of these ia\ines in
which we halted for the night is Shaib Sudaira, in whose bed
of solid well-worn limestone rock is a group of three pools of