Baharia Oasis

by John Ball; H. J. L. Beadnell

Top.	(Limestone, the basal bed of the intermediateseries).
	Limestone, the basal bed of theintermediate series.
	Sandy beds with hard brown ferruginousconcretionary bands, containing numerous casts of Cyprimeria(Artemis?) Arca, Cucullæa, Odostomopsisabeitrensis, Baculites aff. syriacus, andNeolobites Vibrayeanus	⎫ ⎬ ⎭	50 m.
	Clays, often shaly
	Hard ferruginous sandstone with pocketsof clean white sand

Numerous other sections at different points were examined and measured. Such a series is naturally very variable, and individual beds do not maintain their characters over wide limits, so that correlation of different sections is not possible, except in the roughest manner.

In the southern part of the depression fossils are more frequent, otherwise the beds are very similar.

The series under consideration is by no means poor in organic remains, although the latter are more or less restricted to certain bands and localities. No doubt most of the fossil shells have been removed by solution, etc., as those now existing are generally preserved as pseudomorphs in limonite.

The following is a list of fossils which have been obtained from this series:—[42]

Cucullæa sp.	Odostomopsis abeitrensis.
Arca sp.	Natica sp.
Exogyraflabellata.	Baculites (syriacus?)
E. mermeti.	Neolobites vibrayeanus.
Venus(Artemis?) sp.	Fish-teeth and bones.
Silicified wood and plant-remains(including leaves of Dicotyledons).

As regards the age of these beds, it has already been mentioned that the discovery of Exogyra by Capt. Lyons some years ago, in the basal bands of the series, showed them at least to be Cretaceous, although their correlation with the Overwegi stage, on the supposition that the specimens collected were referable to E. Overwegi, is now shown to be inadmissible. The fairly extensive assemblage of organic remains obtained from this and the overlying series enables the age of the beds to be determined with accuracy, and Dr. Blanckenhorn, who had the first opportunity of making a careful examination of the collection, has pronounced them to be Cenomanian.[43]

The general lithological character of the beds and the prevalence of false-bedded sandstones containing in places silicified wood and plant-remains, including leaves of large trees, point to the conclusion that the beds of this series were deposited in fairly shallow water, perhaps in an estuary, at no great distance from the land.

6.—Limestones and Variegated Sandstones.—In the walls of the south end of the oasis, the series just described is always overlain by a bed of hard, and usually more or less crystalline, limestone. This limestone forms the lowest member of the series now under discussion. At the extreme southern end of the oasis, on the western side, this basal limestone forms a narrow platform, of only some 200 metres width, separating the respective escarpments of the two series 6 and 7. On the same side further north the upper escarpment is usually further back, and in some localities the beds do not form a single well-marked escarpment at all.

The series also occurs forming a line of hills within the depression, these hills owing their existence to a remarkable syncline, by which the beds in question have been folded down to the level of the floor of the depression.