THE ESTUARIES OF JIBAN 61

at the northern limit of the true sands of Al Rimal—repre-
sents the cliff-outline of an ancient sea. Fossiliferous deposits
of Miocene1 age are exposed in the lower strata of the Anbak
and Judairat cliffs, and presumably elsewhere, under a con-
siderable thickness of non-fossiliferous sandstone which
appears to extend far back into the eastern desert, though
its age and geological character cannot perhaps be deter-
mined finally in the present state of our knowledge. The
immense salt-flat extending from north of Salwa down to the
furthest extremity of Sabkha Matti doubtless represents the
floor of the open sea in the days when it penetrated far
inland up these estuaries. And I shall have occasion to
suggest in a later chapter that the same sea extended in
an enormous bay down to the Khiran tract over against
Shanna where it washed the flanks of the Eocene mountains
of the south and east. In those days the distant oasis of
Jabrin also was presumably the upper part of an estuary
whose configuration will in due course be discussed. Nothing
surely can be of greater interest than an attempt to throw
back the veil which hundreds or tens of thousands of years
have drawn over the earth as it was when our earliest ances-
tors knew it or as it was even before the crowning glory of
Creation. It is perhaps a bold task for a layman to em-
bark on, but it is well enough if he bring with him to lay at
the feet of the professors the material needful for the testing
of his fancy's flights.

In this case and at this stage of my journey such material
lay, as it were, at my own feet; for as we descended the
stepped slope down to Anbak we marched upon a surface
littered with fossil oysters, such as we had already found in
the cliffs of Qarn Abu Wail. My companions chafed at my
desire to halt, which would delay their coffee-bibbing. But
halt I must, and I begged them to leave me to my work and
go forward to pitch the camp. It was decided therefore that
those who were fasting and were thus debarred from coffee in
any case should remain behind with me, while the rest went
on for their refreshment. For four hours under the afternoon
sun we laboured, collecting and sorting the fossils about us,

1 See Appendix.