Arkell.1956.Jurassic..

398 RANGES OF SOUTH-EAST ASIA
Dactylioceras, Porpoceras, Fuciniceras, Protogrammoceras and Polyplectus,
with the peculiar genus Sphenarpites (Holland, 1909; Spath, 1936). At a
lower level near Kelat and on the Porali River, Las Bela State, occur
Boulieceras and an associated fauna of Fuciniceras and abundant Spiriferina
and Pecten ambongoensis Thevenin, as found in Madagascar and
Jebel Tuwaiq in central Arabia. There are also many other brachiopods,
etc. (Holland, 1909, p. 27).
SINEMURIAN
Crinoidal limestones and shaly beds in the Shirinab valley, south of
Mastung, yielded Arietites aff. bisulcatus (Bruguiere) (Holland, 1909,
p. 26). Since Sinemurian Arietitids are known in southern Persia and in
Tibet this record is not improbable, but it would be more satisfactory if
verified by an ammonite specialist, in view of the homoeomorphy of
certain Fuciniceras, with strongly carinate-bisulcate venters, found in the
Lower Toarcian of Baluchistan.
(Unconformity, teste Burmah Oil Company geologists)
[PERMIAN OR CARBONIFEROUS
Limestones with Productus, etc., locally NW. of Kelat (Vredenburg,
1909, p. 201).]
WAZIRISTAN AND THE SAMANA RANGE
If it is a correct hypothesis that in the Tertiary era peninsular India
moved northwards, it follows that the Jurassic geosynclinal deposits
of Waziristan and adjoining areas to the north would have been squeezed
and pinched between the approaching Indian shield and the smaller horst
of Afghanistan. The Jurassic belt is, in fact, much narrower and more
discontinuous here than farther south, in Baluchistan. The diminution
in width and the discontinuity caused Fox (1931, pi. 10) in
his palaeogeographic map to show a NW.-SE. land-bridge joining
Afghanistan with peninsular India during the Jurassic. That such a
bridge cannot have existed is proved by the Jurassic outcrops of the
Samana Range, which strike right across it. There can be no doubt
that the seaway passed continuously round the projection that caused
the Kashmir syntaxis, from Baluchistan, through Waziristan, into the
Karakorum, as indicated by Wadia (1931, pi. 3).
The festooned trend-lines of the Kirthar and Sulaiman Ranges, repeated
on a smaller scale in Waziristan and the Trans-Indus Salt Range, are
consistent with the postulated northward drive of the Indian shield. If
the movement was as great as supposed there should be extensive tear
faults and perhaps discontinuities among the narrowed Mesozoic outcrops
of Waziristan. Detailed survey in the future should be able to detect these
if they are present. So far little is known of the Jurassic of Waziristan.
In the south, shales containing Virgatosphinctes of the Chidamu Beds of
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