Arkell.1956.Jurassic..

378 RANGES OF SOUTH-WEST ASIA
On the other hand, in parts of the Bakhtiari country the Jurassic is much
thinner. In the SW. scarp of Zardeh Kuh, shown in plate 19, the whole
Jurassic is only about 300 m. thick. The succession exposed in this cliff,
measured by N. L. Falcon, J. V. Harrison and A. H. Taitt, is as follows
(thicknesses as usual converted into metres from feet in round numbers.)
Middle Cretaceous limestone (under snow) . . . . . 600 m.
Lower Cretaceous limestones and shales (nearly to base of the snow) . 675 m.
Jurassic—
Bedded limestones with Erymnoceras 30 m. below top (mostly under
snow) . . . . . . . . . 90 m.
Massive limestones (top of the scarp feature) . . . 24 m.
Well bedded oolitic limestones . 90 m.
Massive dark limestones with Lithiotis near base . . . 90 m.
Massive dark limestone (bottom of scarp) . . . . . 30 m.
Triassic thin limestones and shales . . . . . . . 390 m.
Permo-Carboniferous limestones . . . . . . . 570 m.
Cambrian shales and sandstones . . . . . . . 900 m.
OMAN (EASTERN ARABIA)
The mountain arc of Oman, with heights of up to 10,000 ft., from the
point of view of both topography and geology is a foreign element intruded
upon the Arabian sub-continent. With its arcuate shape, convex to the
SW., fronting the flat sand desert of the Empty Quarter, which seems to be
the prolongation of the Persian Gulf fore-deep, the Oman mountains
stand out of their context as an outlying loop of the Zagros ranges. Whether
this arc continues southwards under the Arabian Sea as some have held,
or joins on to the Kirthar ranges of the Indus arc as the surviving topography
suggests, is still an open question. Certain is it only that the
Oman ranges belong geologically to Asia, both stratigraphically and
structurally, though with differences.
The stratigraphic column for the Mesozoic as determined by Lees
(1928) is as follows, omitting phyllites of unknown age which everywhere
rest on a thrust sole plane and probably correspond with the metamorphic
rocks of the zone of overthrusting in SW. Persia:—
Cenomanian to Maestrichtian limestones.
Semail Igneous Series: a mass of lavas and intrusive rocks forming a
thrust nappe.
Hawasina Series of shales, sandstones, detrital limestones and groups of
red and green chert or radiolarite, with immense sheets of lava
interbedded. Thickness probably of the order of 1500 m.
Musandam Limestone, largely barren of fossils, c. 1500 m.
Elphinstone Beds (Triassic), c. 150 m.
(Permian below)
Clues as to the ages of these rock groups are scanty, as in the zone of
overthrusts in Persia, of which the radiolarite and igneous rocks are no
doubt a continuation. From the middle region (his bed 7) of the
Musandam Limestone, however, Lees collected three corals which
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