26o DERA MAIL AWAY DISTRICT
term is now disused, and the whole area from the hills to the hachi
is called the ddman. It is a level plain without trees and grass, and
except 'where cultivated is unbroken save by a few scattered bushes.
In places even these do not grow, the soil being a firm, hard clay into
which water does not sink readily, though after continuous rain it is
turned into a soft, tenacious mud, and the country becomes impassable.
Such soil is locally called pat. The ddman is intersected by numerous
torrents, which flow from the eastern slopes of the Sulaiman range and
form deep fissures in its level expanse. For the greater part of the
year these torrents are almost dry, carrying but slight streams of clear
water which disappear long before they reach the Indus, but after rain
they become roaring torrents bringing down water discoloured by
heavy silt. But for these streams the dinian would be a desert, but
by arresting their flow and spreading them over the barren levels, the
cultivators transform the whole face of the country; and the richly
cultivated fields, with their embankments planted with tamarisk trees
lying against the background of blue hills, give the tract in places quite
a picturesque look. The kachi or Indus riverain is a narrow strip
of alluvial land beneath the old bank of the Indus, partly overgrown
with tamarisk and poplar jungle and tall Saccharum grass.
The District has only been visited occasionally by geologists. The
greater portion of its surface is occupied by the recent and post-
Tertiary gravels and alluvium belonging to the Indus drainage area.
On its 'western boundary in the Shirani and Sulaiman Hills, the main
formation runs north and south in one great anticlinal arch or fold
with minor secondary folding eastwards near the plains. The lowest
formation seen along the main axis of the range is probably of Jurassic
age, and is a thick, massive limestone. Above it come the so-called
Belemnite shales of neocomian (?) age. Above these lie immense
thicknesses of eocene Nummulitic limestone, sandstone, and shales,
the whole having a resemblance to the Baluchistan and Sind rocks
rather than to those of the country farther north. Over these are the
Siwalik sandstones, shales, and conglomerates of younger Tertiary age,
dipping regularly under the recent deposits of the Indus valley. On
the northern borders of the District the strike bends sharply round
to the south-east and east-north-east, following the curve of the
I3hittanni, Marwat, and Khisor ranges. Here, besides Siwalik con-
glomerate and sandstone, the Marwat and Khisor ranges show the
lower :Permo-carboniferous boulder-bed of glacial origin, containing
boulders of igneous rock derived by ice transport from the Mallani
' C. L. Griesbach, ` Geology oŁ the Takht-i-Sulaiman Range,' Records, Geological
Survey of Ivrdia, vol. xvii, part iv; and T. D. La Touche, ` Geology of the Sherani
Hills,' Records, Geological Survey of India, vol. xxvi, part iii; A. B. Wynne,
' Trans-Indus Salt hange,' 'Memoirs, Geological Survey of India, vol. xvii, part iii. -
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