JURASSIC AND LOWER CRETACEOUS OF WADI HAJAR 



21 



contains the Breadloaf Concretions (0.25 m x 0.25 m x 0.15 m 

 concretions of hard grey limestone), and also a bed of much larger 

 scattered limestone doggers that may be the same as the bed of 

 similar large doggers in Naifa Cliff. 



BIOSTRATIGRAPHY. The age of the Naifa Formation is from the 

 Bimammatum Zone, Upper Oxfordian, to the lower half or two- 

 thirds of the Hybonotum Zone, LowerTithonian.The contact between 

 the Billum and Kilya Members is at the junction between the 

 Eudoxus and Beckeri Zones or within the lower part of the Beckeri 

 Zone. 



1. The Billum Member. The lowest ammonite fauna in the Billum 

 Member occurs in the bottom 5 m in the cliff south of the Wadi Kilya 

 section, and 7-8 m above the base of the member at the base of the 

 Perisphinctid Cliff in eastern Jebel Billum (Figs 5, 12). More than 50 

 specimens were obtained, belonging to the genera Ochetoceras, 

 Epimayaites. Larcheria. Paryphoceras, Orthosphinctes and Eua- 

 spidoceras, which date the beds as Bimammatum Zone, Upper 

 Oxfordian. 



1 8-20 m above the base of the Billum Member in the road cutting 

 at the western entrance to Jebel Billum Glochiceras (G. ) siibclausum 

 (Oppel) and Orthosphinctes polygyratiis (Reinecke) were collected 

 (Fig. 12), which indicate a similar Bimammatum Zone age. 





#-#, 



Fig. 17 Microbialite boulders from the bottom of the Arus Formation in 

 Wadi Arus; A is a complete boulder with an unbroken upper surface; B 

 is a similar boulder broken through the middle showing cross sections of 

 several ammonites; the hammer handle is 34cm long and gives the scale 

 for both photographs. 



WADI ARUS 



Qishn Formation 



[-0 



20 - r l rl' 



-I- i-i- 



-lyl-.l- 



-1' L-;i, 



I I I 



CO 



S-TJ / 



JV-l- 



i;?c 



Tj-^-n 



121 



ZZD 



i"^ , -, ; 



^ 



■1 Aspidoceras sp. indet. (large) 



27 Substeueroceras striatum sp. nov. 

 4 Protacanthodiscus sp. indet. 



Pseudoclambites araense sp. nov. 

 Baeticoceras morrisi sp. nov. 

 Virgatosimoceras broilii (Schneid) 

 Aulacosphinctes spitiensis lUhlig) 

 Aulacosphinctes natricoides lUhlig) 

 Micracanttioceras fraudator (Zittel) 

 Himalayites sp. indet. 

 Spiticeras gregoryi (Spath) 

 Virgatosptiinctes cf. broilii (Uhlig) 

 Berriasella IB. I cf. oxycostata tVlazenot 

 Riasanites rjasanensis (Lahusen) 

 Blanfordiceras waliictii (Gray) 



Microbialite 

 Boulders 



Kilya Member 



Fig. 18 Vertical section of the full succession of the Hajar Formation in 

 Wadi Arus. 



