File 1450/1919 ‘Mesopotamia & Kurdistan: Geological Reports on’ [‎11r] (26/522)

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Upper.
White limestone with poorly preserved fossils. A large part of it is unfossiliferous, but there
are several bands which do contain f issils—Echinids, Gasteropods and Lamellibranchs, also an
organism which may be the remains of Nummulites occurs but is rare. The thickness ot this
limestone is about 1,000 feet. It is possible that this upper limestone may be later than Eocene,
but at present there is no evidence.
Lower Ears Series.
The gypsiferous formation which is called the Lower Ears and is so well developed in Meso
potamia, does not extend east of the Sagirmah Dagh. In only one place was the foimation ou nd>
namely, at the southern end of the Aji Dagh, were it rests comformably on the upper part of the
Eocene Limestone. The formation consists of beds of gypsum from 5 to 20 teet thick alternating
with red shales ; a band of cellular limestone occurs at the base
Its thickness at this place is not more than 300 feet and it appears to thin out against the
south-west flank of the Aji Dagh tovVard the north. The relation of the Lower Ears to the Upper
Ears and the Eocene Limestone will be discussed in the next section.
TTppptp Ears Series.
The Upper Ears beds maintain in general the same lithological characteiistics as in Meso
potamia. The formation consits of red marl and standstone, with very occasional bands of sand^
limestone. It is impossible to divide it into an upper and lower part as the proportion of marl to
sandstone is nearly constant all through. In places the sandstone becomes peebbly. The thickness
is greater than in the Tigris country, but is very hard to determine as there is no boundary between
it and the overlying Bakhtiari Beds ; it is not less than 3,500 feet. In this district it rests on the
Eocene Limestone with apparent conformity. It passes upward into the Bakhtiari and the
boundary between the two is an entirely artificial one.
Bakhtiari Series.
West of Charnchamal and of the Aji Dagh, there is a large area covered by these beds. They
consist of marie and sandstones, the marls predominating in quantity. Conglomerates occur usually
in the upper part, but may come in at other horisons. They vary much in texture, some are coarse
while others only contain small pebbles and have more the appearance of river gravels. The
thickness of the series is very great ; west of Aji Dagh the marls and sandstones are at least 7,000
feet thick. West of Chamchamal there is a great thickness of Conglomerates.above the marly part.
In the Qarah Dagh some conglomerates which have been referred to this series rest on the Upper
Ears beds.
Recent Deposits.
Little attention has been paid to recent gravels and alluvium. In the.valleys east of the
Asmir Dagh there are some high level gravels, which were formed after the folding of the solid
formations. Near Kifri (to fhe South West of the area included in the Report) some gravels
were found which appeared to have been folded with the Bakhtiari beds on which they rested.
In the map and sections recent deposits have not been mapped.
(4) RELATIONSHIP OF THE FORMATIONS AND CONDITIONS OF DEPOSITION.
The oldest exposed formation, the Cretaceous Limestone must have been a fairly deep water-
deposit as shown by the presence of Ammonites and Belomnites. The general appearance is very
like the English Chalk, but harder, and it must have been laid down under somewhat similar-
conditions.
The Eocene Shale Series which succeeds it has shales at the base, which represent shallow
water conditions and the sea must have become shallower when the sandstones and conglomerates
were laid down. The presence of Nummulites show that marine conditions prevailed. This must
have been a period of slow subsidence, with which the sedimentation kept pace. There is no sign
of unconformity.
The Nummulitic Limestone of Eocene age, which follows the Shale series is a uniform deposit,
characterized by the immense number of Nummulites. This was again a period of slow subsidence
and conditions of deposition must have been uniform throughout.
The non-Nummulitic limestone which overlies it has the appearance of a deeper water deposit,
but the occasional bands containing shallow water fossils indicates a return to shallower water
conditions at times.
At the end of the Eocene period a change of conditions set in. The next formation in age is
the Lower Ears, which in Mesopotamia and Southern Persia is characterized by the great quanitity
of gypsum in it. Along the front of the foot-hills from Kifri to Kirkuk it has a considerable
thickness, but it disappears under the Upper Ears beds and only appears again at the south east end
of Aji Dagh, where it has become reduced in thickness to 200-300 feet. Further to the east along
the mountain range of the Sagirmah Dagh, the Upper Ears is resting on the Eocene Limestone
with apparent complete conformity ; no sign of basal conglomerate or transgression could be seen
and both formations have the same dip.
The explanation of this is not clear yet, but the following is put forward tentatively :—
The Eocene limestone had already been affected by folding movements before the deposition
of the Lower Ears and formed a submarine barrier at the beginning of the Lower Ears period.
To the west of it the conditions under which the gypsiferous beds were formed, prevailed ; thus
the Lower Ears thins out against this barrier.

File 1450/1919 ‘Mesopotamia & Kurdistan: Geological Reports on’ [‎11r] (26/522)

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File 1450/1919 ‘Mesopotamia & Kurdistan: Geological Reports on’ [‎11r] (26/522)

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