'File 35/5 Development of Grazing Grounds (Supplies from Persia)' [‎21r] (41/118)

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4) jRoao
IMoJcoassa SO to 50 ft. This ©action ocmaiste of a ©orlas of
©bolos tshioh inolnda© a Idr^srtooo arnbor near their tipper limit. The
limestone member hae been found to be wtcr bearing and at the Refinery
the iTHflaeawm mater bee been found to be loner In dissolved salts than
either the upper Water Zone "B" or the lover water Zone *0** In addition
to the ilveollna bearing limestone a number of other limestones and marl
beds are included and the entire none serves to reinforoe the hindrance to
vertical fluid movomanfc afforded by the underlaying Sharks Tooth Shale 0
5 ) qiwaka Tooth awl. 3 arla»
‘Thickness 6 to 8 ft. The Sharks Tooth 3hale series Is a dense
marly series of shales and is mall developed regionally; it forms an
excellent regional barrier to vertical movsmeut of meter between the over
laying and underlying water bearing strata.
4) 0>aaICc{ .'.ciie
Thickness HO* - 800*. In the exposed area within the Rim Book
the Chalky Zone is composed mainly of limestones, marls and shales. On the
northern plunge of the structure, anhydrite and gypsum are developed to
oonsidarchle aggregate thickness.
A porous series of limestones and doteLtio limestone underlies
m&sm
Iho Bahrein structure is an elongated antlolinal doaas SO miles
long and 18 miles wide, with down-flask dips of 1 to 5 degrees; the major
axis is oriented in the north-south direction. The crest of the deem is
located imodlately cast of Jebal Dukhan in the centre of the Island.
Btelnsfee expresses the opinion that the structural growth of the
Bahrein dome started in the early Cretaceous, or possibly* earlier, and that
the Island has remained a land area since the early Miocene or a period
between 3boane and Miocene. The lend area was evidently subjected to
oansidorabla erosion between the Rocene and Miocene resulting in Mlooene
beds making fairly deep inroads Into the Boemi on the margins of the land
maos. These Miocene beds are in turn covered by the more recent flat laying
deposits on the margins of the present Island.
Subsequent erosions! forces have further exposed formations deep
in the Kooone and in the central basin inside the Rim Rook the beds below
the Shark Toeth Shale series are exposed. These beds constitute the ChalSor
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