﻿674 ME. H. J. L. BEADNELL ON THE EOCENE AND [Nov. I905, 



of a well-marked unconformity between the Cretaceous and Eocene 

 systems. This was based partly on apparent differences of dip 

 between the Ptychoceras- Limestone and the overlying Pecten-Msah, 

 and partly on the occurrence of a bed of rolled pebbles of the 

 Ptychoceras-lAmestone in Wadi Hammama. Their field-evidence 

 appeared to be confirmed by Mr. Bullen Newton's determination 1 

 of the Pectens from the marls as belonging to a new species of 

 true Eocene facies, which he named Pecten Mayer-Eymari, though 

 Dr. Blanckenhorn 2 maintained that the species was identical with 

 Zittel's Campanian and Danian species, P. farafrensis. My 

 colleagues, at the time, felt that the weight of field-evidence 

 supported Mr. Newton's view, especially as the adoption of 

 Dr. Blanckenhorn's determination appeared to involve them in an 

 intra-Cretaceous unconformity. 



Zittel's type of Pecten farafrensis had not at that time been 

 figured, but in 1902 Dr. J. "Wanner described and figured 3 the 

 original type of the species, and Mr. Barron & Dr. Hume added * 

 a note to their memoir (which had already been printed off) 

 admitting the justification of Dr. Blanckenhorn's contention. 



The succession which I observed at Jebel Awaina settles the 

 question once and for all. The P<?cte»-Harls, far from forming the 

 basal member of the Eocene, occur low down in the Cretaceous, 

 near the base, in fact, of a 100-metrc (328 feet) thickness of clays 

 (the equivalent of the ' ashen-grey clays ' of the oases) underlying 

 the Echinocory s-Chalk. Moreover, there is no unconformity between 

 them and the Ptyckoceras-IAmestone below, from which they are 

 separated by a 30-metre (100-feet) band of laminated clays, the 

 occasional slight differences of dip being due to faults and minor 

 local disturbances. 



In the short time at my disposal at Jebel Awaina I was unable 

 to do more than note the principal points in the succession. These, 

 with the approximate thicknesses, are detailed below, in descending 

 order. 



EOCENE. 



Lower Libyan. — 1. Hard limestone with chert-concretions, in part crowded 

 with Nummulites, Operculina, and shells of typical 



Eocene species 20 metres = 66 feet. 



Esna Shales. — 2. Laminated, green and grey, shaly clays, largely obscured 

 (Passage-Beds.) by debris, forming a perfectly-conformable passage be- 

 tween Cretaceous and Eocene 60 metres = 197 feet. 



1 ' Notes on some Lower Tertiary Shells from Egypt ' Geol. Mag. 1898, 

 pp. 535-36. 



2 ' Neues zur Geologie & Paliiontologie iE°ryptens : II — Das Palaeogen ' 

 Zeitschr. d. Deutsch. Geol. Gesellsch. vol. lii (1900) pp. 411-12. 



3 ' Die Fauna der obersten weissen Kreide der Libyschen Wuste ' Palaeonto- 

 graphica, vol. xxx, pt. ii (1902) pp. 114-15 & pL xvii, figs. 1-4. 



4 ' Topography & Geology of the Eastern Desert of Egypt ' Egypt. Geol. 

 Surv. Eeport (Cairo, 1902) footnote, p. xi. 



