ON THE GEOLOGY OF THE NILE VALLEY. 483 



10 miles east of Luxor ; they are also visible in a little-frequented 

 locality near Deir-el-Bahri and more prominently near Nagada. 

 The haematite nodules lie here in thick beds, having apparently been 

 left by the degradation of the clays exposed on the faces of the hills. 



About 15 miles north of Esneh, at Jebel Ain, the river passes 

 between the upturned limestone-beds, which here have again sub- 

 sided, the fault being this time parallel to the river. The calcareous 

 strata here seem to be much thicker than at Luxor, if one may 

 judge by the number of successive limestone-beds appearing above 

 the plain and lying at an angle of about 30°. Possibly, however, 

 these outcrops may be due to a succession of faults repeating the 

 beds. 



About 5 miles south of Esneh, after passing through about 1 mile 

 of very broken and confused clays and sand-beds full of ochre and 

 ochreous nodules, we come to the sandstone. This is chiefly inter- 

 esting from the fact that it is carbonaceous and that it may be of 

 Carboniferous age.^ A shaft, 296 metres deep, still exists at Eedesieh, 

 in the hiUs near Edfoo on the eastern bank, dug 40 years back in 

 searching for coal. We took out of the pit-heap near this shaft car- 

 bonaceous shale which would burn if placed in a fire ; the mass of 

 the strata in the pit is pale blue clay. In the desert west of Edfoo 

 are a series of clays of all colours and thick seams of impure 

 haematite. 



A possible indication of carbonaceous matter lies in the fact that 

 sulphur in the form of sulphates occurs in many beds where its 

 presence can only be explained on the assumption that the beds 

 themselves were attacked by sulphur acids (sulphurous ?). As ex- 

 amples we may quote the occurrence of calcium (and strontium) 

 sulphates in the limestone-beds forming the Mokattam Hills between 

 Cairo and Helouan, and the basic iron sulphates among the haematite 

 of Luxor ; these last have exactly the appearance of native sulphur ; 

 acid waters have also been found, notably at Bahnesa. 



Just before reaching the Assouan granite-formation the Nile 

 crosses a very ancient river-bed, running from W. to E. near Ko- 

 mombo. The deposits of this river form the western bank of the 

 Nile for nearly a mile at Komombo. 



The Nubian hills above Assouan are nearly all sandstone, except 

 where the granite breaks through at Kalabsheh, and we believe that 

 the granite is intrusive, the sandstone at the line of junction having 

 been apparently altered by heat for 50 feet or more.^ 



Some rocks which have been described as volcanic are not volcanic 

 at all. They are merely a silicate coating over the sandstone, 

 formed by water impregnated with silica, iron, and manganese. 



^ [The sandstone (Nubian Sandstone) is generally regarded as Cretaceous. 

 The lower portions, however, may be Carboniferous ; see Sir J. W. Dawson's 

 * Egypt and Syria,' 2nd ed. p. 32, 1887. — Ed.] 



=^'[Mr. J. C. Hawkshaw (Quart. Journ, Geol. Soc. vol. xxiii. 1867, p. 115) 

 describes and maps the sandstones as resting upon the granite. Sir J. W, 

 Dawson (op. supra cit. p. 32) says that the sandstones are ' very much newer 

 than the crystalline rocks, and are derived from their waste.' The crystalline 

 rocks are generally regarded as Archaean. — Ed.j 



