Hyland — On some Specimens from Wady-Halfa. 445 



surface of the Nile valleys is, for the most part, covered with 

 drifted gravel, composed not only of the detritus of rocks in the 

 vicinity, but of rolled pebbles of other formations transported from 

 great distances. For the presence of many of these, the action of 

 existing streams is not adequate to account. The limestone valley 

 of Kossier, near the Red Sea, is covered with a gravel — great part of 

 which consists, according to Newbold, of pebbles from the plutonic 

 and metamorphic rocks of the interior. Few of these pebbles, he 

 adds, are found near the Nile west of the sites of the parent rocks 

 — a fact which indicates the easterly direction of the transporting 

 agency. 1 



There are before me some loose grains which bear the descrip- 

 tion " the so-called Nile rubies, Wady-Halfa." The " rubies " are 

 reddish garnets, some of which show a remarkably well-preserved 

 form (211). Cyanite can also be microscopically determined. 

 Both minerals are evidently derived from the crystalline schist 

 areas. 



Through the kindness of Mr. F. W. Rudler, F.G.S., I am 

 enabled to add a description of the microscopical characters of the 

 desert sand of Korti on the Nile. My best thanks are due to him 

 for permitting me to examine the slides in his possession. As 

 regards the delta-deposits, these consist of admixtures, in varying 

 proportions, of blown sand and alluvial mud. The microscopical 

 characters of these deposits have been carefully investigated by 

 Professor J. W. Judd, and described in a Report to the Royal 

 ►Society. 2 



The sand 3 at Korti differs but slightly from that described 

 by Professor Judd. It is seen upon microscopical examination to be 



1 Newbold, " On the Geology of Egypt," Q. J. G. S., Lon., iv., 1848, p. 326. 



2 Report on a Series of Specimens of the Deposits of the Nile Delta, obtained by 

 the recent Boring Operations. (Communicated by desire of the Delta Committee, 

 Proc. of the Royal Society of London, 1885, xxxix., p. 214 ct seq.) In a footnote to 

 this Paper additional interest is given to the results of the boring at Rosetta by the 

 reported discovery, at a depth of 79 ft. 4 in., of a fragment of red granite possessing 

 undoubted marks of human workmanship upon it. 



3 The sands and muds of the Nile deposits have been subjected by Johnson and 

 Brazier to careful analyses, performed under the superintendence of Hofmann. The 

 results are published in Horner's Paper already quoted. The mud has been also 

 investigated by earlier chemists ; but of all these, Regnault seems to have executed 

 the most minute analysis. (Memoires sur l'Egypte, tome i., pp. 348, 382.) 



