CHAPTER V
JABRIN
' It seems to be an extensive palm tract, now too malarious for
permanent habitation, but visited at the time of date harvest by
Aal Morrah Bedawins, who report that they have seen ruins of
habitations and, after rain, coins lying on the surface of its
SOll.'—D. G. HOGARTH,^1
•
the oasis tracts of Hasa and Jabrin are situated nearly 150
miles apart at the base of a broad belt of steppe whose major
and minor divisions, known by various local names, may con-
veniently be regarded as forming a homogeneous geographical
unit under the general designation of Summan. This steppe
probably overlies Cretaceous,^2 Eocene and Miocene deposits in
that order from west to east and is separated respectively from
the central plateau of Tuwaiq and the sea by two long sand-
arms thrust out northwards by the Great South Desert. The
western arm is the famous Dahna, traceable southwards
through the belt of Rumaila into the great welter of sands of
the Empty Quarter beginning with Bani Ma'aridh, to whose
northern frontier indeed the Summan steppe itself runs down
approximately in Latitude 19 N. under the name of Abu Bahr.
The more easterly sandbelt is Jafura, which we had by now
pretty thoroughly explored and which is itself separated
from the sea by a series of estuary-like coastal indentations,
Its southern fringe is similarly cut off from the main body of
the great southern sands by an estuary of considerable length
and importance running up roughly westward from the sea
to the Jabrin basin at the foot of the Summan. This estuary
is the great Jaub, which is however divided up in local
nomenclature into several sections, the westernmost of which
is the Jabrin basin proper generally known as the Juba.
^1	The Penetration of Arabia, 1905, p. 233.
^2	For geological details see Appendix.