'IRAQ AND THE PERSIAN GULF' [‎72v] (149/862)

GEOLOGY AND DESCRIPTION OF THE LAND
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also a belt of broken country, the plains and foothills of Dohuk with
the outer range of Jabal Bakhair, which may conveniently be ascribed
to this region.
The Plains of Mosul. The eastern half of this area is drained by the
Great Zab and its principal affluent, the Khazir Su; the western half
by a number of lesser streams, the chief of which, the Wadi A seasonal or intermittent watercourse, or the valley in which it flows. Khosar,
rises in the A 1 Qosh foothills and joins the Tigris through the site of
ancient Nineveh, opposite Mosul. The plains are undulating steppe
country with a gentle slope upwards to the north, from 700 feet above
sea-level in the south to about 2,000 feet where the foothills begin to
rise more steeply. Short but prominent hills, marking by their direc
tion from south-east to north-west the strike of the strata, emerge
above the general level, the most important being the Jabal Ain as
Safra (2,206 ft.), Jabal Bashiqa (2,177 ft.), Jabal Maqlub (3,468 ft.),
and Jabal Zirga Bardaresh (1,661 ft.).
The Great Zah, after breaking through the Berat Dagh at the Bekhme
gorge (p. 102), is a wide powerful river at all seasons. At Isteriya,
about 6 miles below Bekhme, its width has been recorded as 400 yards
and its depth about 3 feet in January. Its current has been measured
as 6 miles an hour in both January and May, and it has been forded
by unladen animals in both these months when there has been no
recent rain (photo. 33). In the flood season, or after heavy rain in the
hills, the Great Zab is unfordable either here or elsewhere. Passage is
then only possible by kellek ferries, which are available at several
places, or by the bridge at Eski Kellek.
Below Isteriya the river receives on the left bank the perennial
Mawaran and Bastura affluents which drain both flanks of the Sefin
Dagh (p. 104), but only a little water is added on the right bank until
the Khazir Su enters about 18 miles above the Tigris confluence.
Grass-covered conglomerate hills on the right bank make rough
going, but tracks could be made for wheeled vehicles without great
effort. A river-gauge is maintained at Girdmamik ferry (p. 42).
The Mosul-Erbil road crosses the Great Zab by a steel bridge at
Eski Kellek. The river here is 150 yards wide in October, 10 feet
deep, and has a fairly strong current; it covers its bed three-quarters
of a mile wide in the flood season.
From Bekhme to its junction with the Tigris, a distance of 75 miles,
the Great Zab descends from 1,300 feet above sea-level to about
700 feet, or about 8 feet a mile, and like the Little Zab in its lower
course it breaks up into a number of channels enclosing grass-covered
or sandy islands.