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Tlie beds east of Qus undergo change to an argillaceous sandstone with 
impure limestones and sandstones above, only a few metres of true shales 
remaining. 
THE EXTENSION OF NITRATE SHALES 
0J\ THE LEFT BANK OF THE NILE. 
On the left bank of the INile these shales first appear south-west of Esna at 
the base of the limestone cliffs bounding the desert plateau, further south 
being concealed under the Pleistocene sands, clays and gravels. North and 
south of Esna the distance from the cultivation to their outcrop is from 8 to 
i5 kilometres, but in spite of this every available point is worked by the fel- 
lahin and crMarogn is carried by camels down to the cultivated land. The 
deposits extend 16 kilometres northward of Esna, and then disappear under 
gravels. 
At Gebelain, the shales are again brought into view, while between Erment 
and Qus they seem to be only repi-esented by thin beds of marly limestone 
containing a small amount of Nitrate of Soda. Nevertheless the green shales 
are fairly obvious at the base of the Deir-el-Bahari cliff and in the low foothills 
round Qurna, etc. 
North of Qus and as far as Qena, the shales again appear of their usual 
thickness at the base of the cliff, and also in one or more bands on the plain, 
where their presence (as also at Gebelain) was considered by Messrs. Barron 
and Beadnell to be due to step-faults. In this part the area exposed on both 
sides of the river is very reslricted, owing to the covering of débris from the 
cliffs. It is also much overlain by superficial deposits, and there has been 
considerable erosion. 
WIDE EXTENSION OF NITRATE SHALES 
IN WESTERN DESERTS OF EGYPT. 
These nitrate-beai ing strata are, in fact, but parts of widely-extended for- 
mations, which have been traced from the Oases to the Red Sea, and always 
in the same geological position. To the west of the Nile, they probably occupy 
the low ground at the foot of the Eocene scarp from Esna to kharga Oasis. 
