'IRAQ AND THE PERSIAN GULF' [‎82r] (168/862)

DESCRIPTION OF THE LAND IO 3
Assyrian plains before joining the Great Zab above its confluence
with the Tigris. The mountain pattern of the Khazir Su reproduces
on a small scale that of the Great Zab itself, and reaches the plain
through a gorge between the Chiyakira Dagh and Aqra Dagh. But
south-east of the Zab gorge the Sefin Dagh forms a sufficient barrier
to turn the drainage north-westwards and south-eastwards.
Passages over these barriers are few and far between. The gorges
through them form no natural routes, and though Aqra is easily
reached, the Aqra Dagh is only passable on foot with difficulty. The
Great Zab itself offers no access to Ruwandiz. One main route, using
the accidents of topography, has long been travelled between Erbil
and Ruwandiz, but the old track was only with difficulty converted
by the Turks into a road fit for guns during the War of 1914-1918,
and it took British engineers four years, from 1928 to 1932, to blast a
motor-road through the Ruwandiz gorges to the Persian frontier.
The region is best described in blocks divided by the main river
courses, first the outer barrier ranges, then the highlands beyond the
trough of the Great Zab (fig. 27).
The Outer Barrier south-east of the Bekhme Gorge
The mountains here occupy the country between the Rubar-i-
Ruwandiz on the north-east and the Erbil plain on the south-west.
The easternmost head-waters of the Rubar-i-Ruwandiz drain the
rampart of the Kandil Dagh, the crest of which, beyond the ‘nappe
front’, forms the Persian boundary, and with its massive crystalline
slabs under deep snow for many months is almost Himalayan in
character. West of the range the mountains appear as great spurs of
the Kandil Dagh, but are in reality regular folds running north-west
wards so that the pattern of almost the whole outer barrier is very
markedly from south-east to north-west, a succession of mountain
folds drained in this direction to the Great Zab or Rubar-i-Ruwandiz.
The watershed between the Great and Little Zabs follows a sinuous
line and is governed by the erosive power of each individual stream.
It follows that the natural lines of communication are from south-east
to north-west and that most of the valleys are easier to penetrate high
up in their courses than near their junction with the deeply en
trenched Zab and Ruwandiz rivers. Passages across the mountains
from south-west to north-east are few and far between, a fact which
adds importance to the historic route round the north-western flanks
and over the Spilik pass, and to routes from the Rania plain near
the elbow of the Little Zab (p. 101). Because of the importance of