66 DR. J. BALL OX THE [Feb. I903, 



Although abundant references to the markings, and the change 

 of level which they indicate, are to be found in historical works 

 published since Horner's day, 1 I have been unable to find that the 

 question has been further investigated by geologists. It was 

 evident that a solution of the problem could be expected only from 

 a further careful examination of the locality ; and it was therefore 

 with peculiar satisfaction that I availed myself of the kind 

 permission of Sir William Garstin, the Under-Secretary of State 

 for Public Works, to visit Semna during the Bairam holiday of 

 March 1902, and to publish the results of such examination as I 

 could make there. I was in hope that after a careful survey of the 

 Nile Valley at the place, combined with such data concerning the 

 geology of Nile cataracts as I have been able to pick up during 

 several years' investigation at other points, the enigmatical nature 

 of the marks might disappear. This I believe is really the case ; and ■ 

 I hope to show in the present paper that, owing to the structure of 

 the district, a fall in the level of the river at Semna of the magnitude 

 shown by the inscriptions is the natural consequence of such river- 

 erosion as is going on at the present day, acting through the period 

 of 4200 years indicated by the date of the markings. 



II. Topographical Description of the District. 



Semna is not difficult of access from Wadi Haifa, from which 

 it is about 43 miles distant. The train can be taken as far as 

 Sarras, leaving only about 7i miles to be covered on camel or 

 donkey, and the road is of a highly interesting character, from the 

 variety of igneous and metamorphic rocks passed through. The 

 route is shown on the Wadi-Halfa sheet (35, I) of the map of 

 the Egyptian Sudan recently published by the War Office. 2 The 

 small hamlet of Kumna, situated within the ruins of an ancient 

 fortress, and inhabited by about 60 poverty-stricken but hospitable 

 Nubians, makes the best halting-place ; there are no inhabitants of 

 the ruins of Semna, which lie on the opposite (western) bank. 



Immediately above and below the Kumna and Semna temples, 

 the river has a width of about 400 metres (1300. feet), but between 

 the two temples a narrow band of hard red and grey gneiss forms a 

 natural barrier across the stream. At high Nile the river flows over 

 this barrier without any considerable diminution of its width, though, 

 owing to the shallowness of its path and the irregularities of the 

 gneiss-surface, its velocity is much increased and violent eddies are 



1 See, for instance, Prof. Maspero's ' Dawn of Civilization' 4th ed. (1901) 

 p. 488, or Dr. Budge's ' Egypt under the Amenemhats & Hyksos ' 1902, p. 46. 

 Dr. Budge states that ' various explanations have been put forward of the ex- 

 traordinary change which appears to have taken place in the level of the Nile 

 between the time of Amenemhat III and our own, but none of them clears 

 away all the difficulties in the matter.' 



2 I have followed the orthography of this map in the names of the two 

 villages. They are, however, more usually spelled Semneh and Zummeh ; 

 and, from a Greek inscription cited by Prof. Maspero, in his ' Dawn of Civiliza- 

 tion ' 4th ed. (1901) p. 485, it would appear probable that Eumma is a more 

 correct spelling than Kum»a. 



