h of the Helmund, entirely
shutting off that valley and the approach to Seistan between the Helmund
and the Gaud-i-Zirreh (the only approach from the east in seasons of flood)
from Baluchistan. But it leaves a connected line of desert route between
Nushki and Seistan, which is open in all ordinary seasons, to the south,
and this route has been largely developed, posts or serais having been
established at intervals and wells having been dug. There is already a
promising khafila traffic along it and the railway has been extended from
Quetta to Nushki.

_Geology._[1]--The mountain ranges of Baluchistan consist chiefly of
Cretaceous and Tertiary beds, which are thrown into a series of folds
running approximately parallel to the mountain ridges. The folds are part
of an extensive system arranged as if in a festoon hanging southwards
between Peshawar and Mount Ararat, but with the outer folds looped up at
Sibi so as to form the subsidiary festoon of the Suliman and Bugti Hills.
Outside the folds lie the horizontal deposits of the Makran coast, and
within them lies the stony desert of north-western Baluchistan. In the
broader depressions between the mountain ridges the beds are said to be but
little disturbed. Besides the Cretaceous and Tertiary beds, Jurassic rocks
are known to take a considerable part in the formation of the hills of
British Baluchistan. Triassic beds lie along the south side of the upper
Zhob, and _Fusulina_ limestone has also been found there. With the
exception of the later Tertiary beds the deposits are mostly marine. But in
the upper Cretaceous and lower Tertiary, especially in north-western
Baluchistan, there is an extensive development of volcanic tuffs and
conglomerates, which are probably contemporaneous with the Deccan Traps of
India. Great masses of syenite and diorite were intruded during the
Tertiary period, and within the curve of the folded belt a line of recent
volcanic cones stretches from western Baluchistan into eastern Persia. In
Baluchistan these volcanoes appear to be extinct; though the Koh-i-Tafdan,
beyond the Persian frontier, still emits vapours at frequent intervals. The
lavas and ashes which form these cones are mostly andesitic. Mud
"volcanoes" occur upon the Makran coast, but it is doubtful whether these
are in any way connected with true volcanic agencies.

So far as is known, the mineral wealth of Baluchistan is inconsiderable.
Coal has been worked in the Tertiary beds along t