1092 Appendix Il: Phytogeography and Geology. 
lies a black clay, never yet penetrated by the boring rods; it is 
probably that other water tables exist below and such would be in 
valuable for the inrigation of those parts of the oasis where the 
present supply is unsatisfactory. There seem to be no natural springs 
extant at the present day, the whole of the water-supply being 
through boreholes both ancient and modern. 
It is probably that the water bearing table has its outcrop in 
the rainy regions of Darfur, although some of its water may be 
derived by direct infiltration from the Nile in its upper reaches. 
V. Great Oasis'). The Great Oasis or Kharge, the eastern 
most of the two southern oases, is a north and south lying depression, 
mostly bounded by steep and lofty escarpments but open to the 
south and south west. A great part of its floor, which is composed 
of the Nubian sandstone is burried under sand accumulations. The 
adult palm trees in the oasis number about 60000 and the eulti- 
vated lands have an area of some 4500 acres. The crops raised 
do not appear to be sufficient to support the population, as a certain 
amount of grain is imported from Dakhel. Dates are exported to 
the Nile Valley, though in less quantities than from Dakhel and the 
Little Oasis. 
The general level of the floor of the oasis lies between 50 and 
130 metres above sea level, though near Qasr Zaiyan a limited area 
appears to lie below sea level. Water is met with in most localities 
on digging to a moderate depth, but the best supplies are from deep 
wells; as in Dakhel the majority of the wells are of considerable 
antiquity, though some have been recently made with modern boring 
plant. With an increased water-supply cultivation could be very 
much extended, as there are large areas of unoccupied alluvium 
covered land within the oasis. 
The oases-revion has only a few special-plants not more than 
some twenty and only 3 endemics. In the following list those species 
of tropical-african origin are marked by an 7: 
+ Maerua crassifolia. + Striga gesnerioides. 
Silene gallica. Rumex pulcher. 
+ Cardiospermum Halicaceabum. Populus Euphratica. 
Lotus lamprocarpus, Potamogeton pusillus, 
Pimpinella Schweinfurthii. , > Lemna paucicostata. 
Duecrosia Ismaélis. | ++ Cyperus polystachyus, 
* Sonchus maritimus. ar ;  Mundtii. 
+ Utricularia exoleta. Trisetum Rohlfsii. 
Convolvulus pilosellifolius. + Antoschmidtia quinqueseta. 
+ Cordia Gharaf. + Marsilia diffusa, 
Veronica aquatica. 
') Beadnell: An Egyptian Oasis. — London 1909. 
