[32]Includes about 50 inhabitants of the hamlet of Harra.
[33]A bottle of the water tightly corked burst shortly afterwards by gaseous pressure; the bottle having been filled at the bottom of the well doubtless accounts for this, the pressure due to the head having caused solution of the gas to a greater extent than could be supported at the surface. The evolved gas was at first suspected to be methane, as there is frequently a great deal of decaying vegetable matter in the mouths of the wells; but it extinguished a taper, and, moreover, the water runs too rapidly for any accumulation of gaseous decomposition-products to take place.
[34]In Dakhla and Kharga Oases there are only seven and a half and eight trees respectively per inhabitant.
CHAPTER V.
Geology of the Oasis.
Previous geological work.The earliest geological observations made in Baharia Oasis appear to have been those of Cailliaud,[35] who visited the district in 1820, and recorded the occurrence of volcanic rocks within the depression.
In 1874 the celebrated Rohlfs Expedition was organised, and in that and the succeeding year traversed large portions of the Libyan Desert. The work of this Expedition, forms indeed, the basis of our knowledge of the geology of Egypt generally. The eminent geologist and palæontologist of that Expedition, Karl A. Zittel, did not, however, visit Baharia, and the only information with regard to the geology of this oasis was derived from specimens collected by Prof. Ascherson. After examining these, Zittel stated[36] that the floor of the oasis consisted of sandstones, marls, etc., presenting a considerable resemblance to the lower part of the Overwegi stage;[37] but concluded, that as they were succeeded at a very short interval by Nummulitic Limestone, precluding the possibility of the higher Cretaceous beds, except in a very attenuated form, they must be of Tertiary age.
In 1894, Capt. H. G. Lyons, R.E.,[38] visited Baharia, and 5 miles N.N.E. of Zubbo discovered a bed containing small examples of Exogyra. These were examined by Prof. Zittel and referred to as undersized specimens of Exogyra Overwegi Beyr.[39] This discovery of Capt. Lyons’ thus showed the series to be undoubtedly of Upper Cretaceous age.