'IRAQ AND THE PERSIAN GULF' [‎50v] (105/862)

58 GEOLOGY AND DESCRIPTION OF THE LAND
spicuous Bazian fold (Qara Dagh, Kani Shaitan Hasan), and the
more rounded Baranand Dagh. Pir-i-Mukurun forms a fourth and
much more marked elevation. North-east of it from two to five
others, tightly packed, can be traced in the Sulaimaniya country
before they disappear under the rock slabs some 20 miles north-east
of Pir-i-Mukurun.
Between the two Zabs, in continuation of this group, there are
several closely packed parallel folds. Hab-es-Sultan Dagh and Sefin
Dagh are two conspicuous units which act as a formidable barrier
between the Erbil plain and Ruwandiz. North-east of them a large
fold crosses the district near Rania, but north-west of the Sefin Dagh
the strata are more robust and less pliable, so that the folds do not
reach the Zab and are barely noticeable beyond. The broad plain of
Erbil, south-west of this mountain group, is covered by alluvium,
which is only broken by the low Demir Dagh.
West of the Great Zab four folds rise from the plain between 20
and 30 miles north-east of Mosul. The southernmost appears to be
a continuation of the Demir Dagh, but the Jabal Maqlub is the most
conspicuous. Farther north near Aqra the strike gradually changes
from north-west to a more westerly direction. The folds are mostly
broad and rather gentle, though they are deeply cut by gorges, and
near Amadia the lowest rocks known in Iraq are revealed. About
Dohuk they become still broader and tend to diverge, the northern
folds keeping west-north-westerly and the southern trending westerly.
Beyond the frontier in the northern Jazira of Syria and in southern
Turkey the number and size of the folds decline, but some become
conspicuous again west of the Euphrates between Palmyra and
Damascus.
Beyond the more or less regular folds which have been described,
but within the Iraq borderland, the topography is less regular and
less clearly related to the structural foundation. Thin sheets of lime
stone take the place of massive beds. These wrinkle up in confused
packets which erosion tends to remove quickly. Their corrugation
into a great number of small folds is facilitated by the inter-layering
of shales between the thin limestone beds. North-east of it, beyond
an irregular line—the ‘nappe front’—running from near Halabja
across the basin of the Little Zab to the Turkish frontier near Nahala,
slabs of disturbed rocks are packed like gigantic tiles. The mountains
formed are often serrated, and unexpectedly jagged teeth stand up,
whilst the landscape is affected by the variegated colours of the out
cropping rocks. Red cherts, green igneous rocks, grey slates, and at