'IRAQ AND THE PERSIAN GULF' [‎85v] (175/862)

Io8 GEOLOGY AND DESCRIPTION OF THE LAND
feet above sea-level. The crest surmounts a precipitous wall above
the northern slopes. A parallel rocky ridge on the north, between
6,000 and 7,000 feet, is joined to it at its western end and is intersected
by rivers flowing northwards in deep gorges. The formation suggests
that the ridges were once part of a plateau which has since been dis
sected by torrents. The slopes are wooded; vines and tobacco are
grown on terraces near sheltered villages.
The Piris Dagh is an eastern continuation of the Ghara Dagh, but
it has been eroded deeply along its original crest by the Zibar tribu
tary of the Zab and by tributaries of the Khazir, which have eaten
into the softer rocks, leaving two main ridges still standing at about
6,000 feet. The northern ridge, known as Cha Keri on the west, rises
south of the elbow of the Zab and extends east from the northern
Ghara Dagh for 21 miles. At Sar-i-Sura the ridge broadens, and its
northern slopes fall steeply for 4,000 feet to the Zab. South-west of
Cha Keri there is a col of 3,500-4,000 feet between it and the Ghara
Dagh. East of Sar-i-Sura the ridge is crossed by the Gali Shini pass
( 3> I 55 ft-)> an d it ends just north of Zibar.
The southern ridge extends for 30 miles in an east-south-easterly
direction, south of the Zibar valley and the trough of the Zab. On
the west its narrow crest, between 4,000 and $,000 feet, sends out
short rounded spurs; farther south-east these lie parallel with the
range, enclosing narrow valleys. North-north-east of Aqra the ridge
is crossed by the Gali Sharita pass, at over 4,75° feet. Here it forms a
sinuous watershed with summits of over 5,000 feet, but it broadens
eastwards. The northern slopes are less steep than the southern. A
track from Amadan to Zibar crosses the Gali Piris pass east of Ser-i-
Piris. The ridge ends with a rocky summit of 5,700 feet. The lower
slopes on both sides are wooded.
The two ridges of the Piris Dagh are connected by a jagged crest
4 miles long with summits of 6,000 feet at the head of the Zibar valley.
With the Ghara Dagh they enclose the head-waters of the Khazir in
a high fan-shaped basin from which the river passes southwards in a
defile between the southern ridges of the Ghara Dagh and of the Piris
Dagh, and their outliers. The Bare Shor tributary of the Khazir, the
head-streams of the Bereshu, and the Suse stream flowing east into
the Zab, all drain the southern slopes of the Piris Dagh.
The Highlands north-east of the Great Zab Trough
The complex topography north-east of the Zab trough is best
understood by a reference to fig. 15, where the structure and drainage