42 Reports and Proceedings — Geological Society of London. 



REPOETS ^.JSTID PROCEEDI1TGS. 



I. — Geological Society of London. 



November 23, 1910.— Professor W. W. Watts, Sc.D., M.Sc, F.R.S., 



President, in the Chair. 



The following communications were read : — 



1. " The Effects of Secular Oscillation in Egypt during the Eocene 

 and Cretaceous Periods." By William Eraser Hume, D.Sc, E.G.S., 

 Director of the Geological Survey of Egypt. 



The main points considered in the paper are : — 



A (1). There is evidence of the gradual advance of the Cretaceous 

 sea from north or north-east over Egypt during Upper Cretaceous 

 times. Four stages in this advance are indicated hy the geographical 

 distribution of the Cretaceous deposits, and especially by the relations 

 of the detrital Nubian Sandstone formation to the organic Cretaceous 

 limestones. The four phases are : (a) A North Egyptian type, in 

 which the Nubian Sandstone entirely underlies fossiliferous beds of 

 Cenomanian (Lower Chalk) age. This extends across Egypt from 

 Sinai to Baharia Oasis, (b) A Wadi Qena type, developed near the 

 head of the valley of that name, characterized by the alternation of 

 Nubian Sandstone with fossiliferous Cretaceous beds. Three main 

 divisions of Nubian Sandstone are recognized — one at the base of the 

 Campanian (in the Upper Chalk), another above the Turonian (Middle 

 Chalk), and a third below the Cenomanian beds, but closely related 

 and passing into them. The recognition of the type was one of the 

 most interesting results of this year's expedition in the Eastern 

 Desert. (<?) A Central Egyptian or Hammama type, in which the 

 Nubian Sandstone forms the greater portion of the Cretaceous Series, 

 only the Danian and Campanian beds being fossiliferous limestones or 

 shales. This section is divisible into an Eastern facies, in which 

 Pecten Marls are a special feature ; and an Oasis facies, characterized 

 by a fauna of small Gasteropoda, etc., in the shales, and species of 

 Ji'chinocorys, crinoids, and Terebratulina gracilis, etc., in a white chalk 

 indicating a close affinity to the White Chalk of Northern Europe. 

 These two divisions have been linked together by the discovery of the 

 shales with the typical Oasis and small Gasteropod, etc., fauna in the 

 same series as the Pecten Marls, and overlying them. The Campanian 

 beds are characterized by the presence of phosphatic fish - beds. 

 (d) A South Egyptian type has close resemblances to the Central 

 Egyptian ; but in the Campanian the phosphatic beds are inconspicuous, 

 and a fauna of sea-urchins was discovered consisting mainly of new 

 species. 



The results of the Eastern Desert expedition of 1910 in Wadi Qena 

 bear the strongest testimony to the Cretaceous age of the Nubian 

 Sandstone. 



B (2). As regards the transition from the Cretaceous to the Eocene, 

 the following points are noted : The existence of two types of strata 

 at the base of the Eocene: the first, the Luxor type, being fossiliferous, 

 mainly characterized by the presence of Operctdina libyca, etc., and 

 largely developed in the Western Desert ; the second, or Qena type, 

 being on the other hand entirely unfossiliferous, and composed of 



