File 1450/1919 ‘Mesopotamia & Kurdistan: Geological Reports on’ [‎14v] (33/522)

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(5) GEOLOGICAL STRUCTURE.
Pressure from the north-east has been the governing factor in the general structure of the
district and the orientation of all the anticlines is in consequence NW-SE.
The country divides itself into (1) A mass of hills in the north-east and (2) A broad plain
formed of Upper Ears and Bakhtiari beds in the south-west broken by three anticlines in which
lower formations are exposed i.e., (a) Qarah Chaugh Dagh, (k) Quwair dome, (c) Avanah Dagh.
(1) The Hill Country.
About 5 miles to the north-east of Arbil Bakhtiari Beds emerge from the plain with a low dip
to the S.W. and rise to form a barrier of conglomerate hills along the whole front of the Kurdish
hills.
Beyond this barrier the general structure of the country appears to be that of a big
anticlinorum with a Cretaceous limestone core. The south-east end of the anticlinorum lies to
the north-west of Sulaimaniyah. where it is echeloned on another further to the east. Thence it
runs north-west to the Greater Zab beyond which we have no information, except that the flanking
Eocene ranges on the south-west of the uplift all plunge under at the river.
The maximum uplift would appear to be on the Arbil-Rowanduz line. The further side of this
anticlinorum was not reached on this examination, but the structure has been inferred from infor
mation received and from a comparison with the Sulaimaniyah district.
In detail the country consists of parallel N.W.-S.E. ridges echeloned on one another, in which
the core rocks of the anticlinorum become more and more dominant as one travels to the N.E.
Usually here, as elsewhere in the country, anticlines form the hills and synclines the valleys, but
near Rania valleys are found in the Cretaceous due to the erosion of the core of an anticline.
• The dominant feature of the structure is the degree of echeloning. This is particularly notice
able \n the Cretaceous rocks where no single ridge is a simple anticline but a closely packed bundle
of echeloned anticlines, which die out and are replaced by others as the ridge is followed along.
Another feature worthy of mention is the tendency of the strata when highly folded to pass from
vertical into reverse dip in places on both sides of the anticline, forming incipient “ Fan-structure ”
I he plains such as Betas, Koi Sanjak, Rania and Pishder are structural plains due to the plung
ing of anticlines. ^
No faulting or thrusting was observed in this hill mass.
(2) The Upper Ears and Bakhtiari Plain.
(a) The Qarah Chaugh Dagh—This uplift consists of two main hills with a N W S E orientation
composed of Lower Ears rocks with Eocene limestone coress. They are joined to one another bv
an b shaped ridge in which only Lower Ears is exposed. On the bend of the “S” the hecU
are crushed up into a small subsidiary dome. Both hills are anticlinal and nearly symmetrical
n,e dips on either flank are 45-50 degrees, but the dip on the south-west is the more constant of
t ('in T n-„ L ° W ?, r , Fan >, c0 " ies out from beneath normal Upper Pars and is found far up on the
sides ot the hills Below the Lower Pars, which here is about 1,100 feet thick, well exposed in the
deeply eroded valleys, is about 1,000 feet of White Rocene Limestone of the same type £ described
hom the Sagirmah Dagh (See Geological Report No. 8). Below again there is a core of ,
chalky fissile limestone rather crushed with nodules and cubic crystals of Iron Pyrites We saw
about 100 feet of this rock in a deep ravine in the southern Hill Two corals in Trrm p a '
obtained from this limestone. alS 111 Ilon P > Tltes were
Porro and Kissling describing the beds below “the Gypeum horizon” snv “ Ac ™ ,
ngier on the Kara-Tchock one reaches a massy zone of limestones some 80 metres thic^ which
contain frequently gasteropodes, alveolmes, corals, Nummulites and the remains of echi des On ’
can easily see how they cover as a vault a light grev massv limestone Z ecmmdes One
ravines are cut Some 350 metres of the limestone of the coic are disclosed L rSes'.” P
•*w Ve U? d ! ffi T' t0 correla te their section with ours, but we believe that the ton \n *
with fossils to be the limestones at the base of the Lower Pars in which the,, tL to P 80 metres
not very obvious gypsum beds. Their " core-limestone’■ won d then represenf™ r ? I Verloo t, ed the
Limestone. We examined the hills from Makhmur a village on the ,, ti. ? ' 1 Upper Eocene
the section they examined, which must have been on the north-east flaiik oTthe'northenrMl'’ 01
plunges to LTorih^M ' at ^ northern extremity i,
(b) The Quwair Dome. —From Quwair village on the left hunL fLo, n i. ^ ,
Pars beds runs in a S.E. direction. This inlier is about three mile m Z; ' b a fold of Lower
greatest breadth. There is a low but disfinet plunge at each end Thp 8 ‘’'’’f 4—1 mile broad ;lt
miles from the village of Quwair along the Dibega road which herL Cr ? t . max,mum is about H
ridges which from a double crest to the fold A second’ crest m- llm between two low parallel
yards to the south east but the drop in height between the twnTs eX ‘ St , a few hundred
The general fall of the beds to the flank of the antidi eTs a out a O He " to bp negligible.
20 degrees to the S.W, but the dip is very variable and m uch complicated b ^ ^ ^ »bout
limestone. On the north-east flank the Lower Pars dip under normal IW puckers in the
SXexdlll £d. in ° --“"d tt S^was
dt 61 ?!.! 50 ^^ The seepage occiudo’“l' ^ N f limb a nd
Plunge of the axis. Dr. Pascoe notes that the axis of the domeir^ghtly sigmddal. n ° rth ' WeSternly

File 1450/1919 ‘Mesopotamia & Kurdistan: Geological Reports on’ [‎14v] (33/522)

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File 1450/1919 ‘Mesopotamia & Kurdistan: Geological Reports on’ [‎14v] (33/522)

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