Arkell.1956.Jurassic..

THE MIDDLE EAST 289
the NW. corner of the Great Bitter Lake (Abu Sultan) and under the
Cretaceous dome of Abu Roash, on the west edge of the Nile valley north
of Giza pyramids (Chata, 1951, p. 91).
At Abu Roash a well drilled in 1946 (of which the log and reports have
been kindly made available to me by the Standard Oil Company of Egypt)
proved pink granite basement at 1898 m., overlain by 336 m. of Carboniferous,
806 m. of Jurassic, and 152 m. of Nubian Sandstone. The Jurassic
rocks consisted mainly of shales, with subordinate sandstones, and were
identified by lithology and micro-fauna, but the only macro-fossil recognized
was a Nuculana. The micro-fossils do not admit of reliable subdivision.
So great a thickness of Jurassic shows that stratigraphically
as well as structurally the Abu Roash dome is comparable with Gebel
Maghara in northern Sinai.
At Abu Sultan, near the NW. corner of the Great Bitter Lake, under
the Tertiary (Oligocene ?) were penetrated 275 m. of beds presumed
to be pre-Nubian Sandstone and probably all Jurassic, unbottomed
at a depth of 757 m. The lower part yielded species of Nucula,
Nuculana, Astarte, Gervillia, Eligmus, etc., and were compared to the
Bathonian; at two levels were beds crowded with Posidonia. Higher up
were pelecypods and some brachiopods thought to be Oxfordian to
Callovian (Report kindly made available by the Anglo-Saxon Petroleum
Company).
Across the peninsula of Sinai all rocks below the Cretaceous Nubian
Sandstone crop out south of the line where the Jurassic thins away.
Between the Eocene and Upper Cretaceous limestone plateau of central
Sinai (Gebel Egma and Gebel Tih) and the pre-Cambrian crystalline
rocks of southern Sinai, the Nubian Sandstone outcrop runs in a continuous
strip from a point midway down the Gulf of Suez to the head of the Gulf
of Akaba. In this outcrop no sign of Jurassic rocks has been reported,
although on the west side there is a continuation of the marine Carboniferous
of Wadi Araba (Ball, 1916). Upon the Nubian Sandstone follows
marine Cenomanian.
GEBEL MAGHARA, NORTHERN SINAI
Fifty miles east of Ismailia, which stands at about the centre-point of
the Suez Canal, the low-lying and largely sand-encumbered plains of
north Sinai are broken by the massif of Gebel Maghara (Djebel Moghara
in the French literature). The group of mountains forms an ellipse about
25 miles long by 15 miles wide, the long axis running SW.-NE. On the
average they reach 1500-2000 ft., and the highest point, Shusht el Maghara,
attains 2412 ft. The structure is a pericline, in the centre of which Jurassic
rocks occupy an ellipse measuring 23 miles by 9 miles. Not far away
two other small inliers of Jurassic rocks (limestone believed to be Lower
Kimeridgian or Upper Oxfordian in age) occur in the isolated dome of
Gebel Um Mafruth (852 ft.) and a hill called Jeham, in the Risan Aneiza
group (Farag, 1947).
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