Vol. 59.] THE SEMNA CATARACT OF THE NILE. 69 



number of such records, roughly sculptured on the gneiss-rocks 

 below the temples, are to be seen. 1 localized and copied several 

 of these on the Kumna side, and am indebted to Prof. Maspero, the 

 Government Director-General of Antiquities, for the translation of 

 the hieroglyphs. One inscription, situated 10'9 metres (36 feet) 

 above the present high-Nile level, reads as follows : — 



" Level of the Nile of the year XXT1I, under the majesty of King Nimaitra, 

 Son of the Sun, Auienemhat, giving life, stability, wealth, like unto the Sun for 

 ever and ever.' 



A group of other inscriptions l of different years, in which the 

 same formula is used, are situated just below the Kumna temple at 

 an altitude of 7*9 metres (26 feet) above the present high-Nile level. 

 It should be explained that, although I did not myself see the place 

 when the Nile was in flood, yet there can be no doubt of the 

 correctness of the differences of level noted, as the people of Kumna 

 pointed out the precise spot where they go to get water at high 

 Nile. ALy observation of the magnitude of the fall of the river 

 between e.c 2300 and the present day, thus confirms that of 

 Lepsius. 



It would appear to be no difficult matter to dam up the river by 

 a filling of heavy blocks in the central channel, but I failed to find 

 any evidence of the former existence of an artificial dam at the 

 place, such as Sir W. Willcocks suggests 2 might have been built by 

 Amenemhat. 



III. Geology. 



The rocks near the river are igneous and metamorphic for a 

 considerable distance both up- and down-stream of Semna. They 

 consist of granite, diorite, gneiss, and hornblende-schist, with 

 dykes of porphyry and quartzite. West of Semna, at a distance of 

 about a kilometre (5 furlongs) from the Nile, these rocks are overlain 

 by Nubian Sandstone, forming the conspicuous hill called Jebel 

 Barka. On the east side there is no Nubian Sandstone near the 

 river, though Dr. W. F. Hume informs me that it exists farther east 

 than I ventured to wander. 



The Gneiss. 



The rocky barrier which stretches across the stream between the 

 two temples consists entirely of very hard red and grey gneiss, 

 the foliation-planes of which strike parallel to the direction of the 

 river (that is, north-eastward), and dip about 30° south-eastward. 

 The foliation is extremely marked, the rock being very fissile in 

 spite of its hardness, and the steeply-dipping foliation-planes form 

 slippery slopes polished by the annual dragging over them of the 

 countless tons of sand and silt brought down by the river. The 

 portion of the barrier which is laid bare at low Nile is honeycombed 

 with large potholes (fig. 2, p. 70), which attest the powerful grinding 



1 This group and the preceding inscription correspond, I find, with those 

 figured as K and L respectively in pi. cxxxix of Lepsius's ' Denkmaler ' (pt. ii). 



2 ' Egyptian Irrigation ' 2nd ed. (1902) p. 30. 



