THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE III. VOL. I. 



No. XI.— NOVEMBER, 1884. 



o:RXGrXi<rj^Xj jv^k,txgxjES. 



I. — Notes on the Geology of the Nile Valley.^ 



By Sir J". William Dawson, K.C.M.G., LL.D., F.E.S., F.G.S., etc., 



Principal of McGill College, Montreal. 



V. — General Bemarhs and Conclusions. 



WE are now in a position to indicate the succession of geological 

 events in Egypt, and to compare them -with those of neigh- 

 bouring regions. 



1. The original foundation of this part of Northern Africa was 

 laid in those movements of the Old Laurentian beds which in so 

 many regions gave the first form and direction to the continental 

 masses. It would also seem that in Egypt, as elsewhere, the folding 

 and crumpling of the Laurentian was accompanied and succeeded by 

 the emission, from the interior of the crust, of masses, veins and 

 beds of igneous and aqueo-igneous material, penetrating and over- 

 lapping the upturned Laurentian strata, and accompanied with the 

 deposition of the material of a newer crystalline series. I have 

 described these phenomena as seen at the Island of Biggeh, near 

 Philfe ; and it seems probable, from the descriptions of Lartet and 

 others, that some of the porphyritic beds seen on the flanks of Mount 

 Hor, and elsewhere in Arabia, are of the same character with those 

 of Biggeh, and may be regarded as representing the Arvonian or 

 the Huronian of more northern countries. As stated above, the 

 anorthosite gneiss, which is the material of the statue of Cephren in 

 the Boulak Museum, may indicate a representative of the Noriau 

 series in the crystalline mountains eastward of the Nile. 



2. The argillites and chloritic and other schists used by the 

 Egyptians in the manufacture of many minor sculptures, and said 

 to be associated with the celebrated green breccia of Cosseir,''^ are 

 probably of somewhat later age, since the breccia contains fragments 

 of several of the older rocks. They are certainly, however, older 

 than the Carboniferous, and not improbably pre-Cambrian. They 

 have particij)ated to some extent in the disturbances of the older 

 formations. 



3. In the later Palasozoic period the crystalline rocks seem to 

 have constituted insular tracts in a shallow sea, in which sandstone 

 was being deposited. It seems definitely ascertained that the lower 

 sandstones and limestone of Wady Nosb and other places in the 



1 See also former articles, pp. 289-292, 385-393, 439-442. » Lartet. 



DECADE III. — VOL. I. — NO. XI. 31 



