5S2 PEOF. J. W. GEEG0EY ON [Nov. I9II, 



From the edge of the plateau above the Wadi Nagr the country 

 rises gradually westwards and southwards, although the surface is 

 broken by deep wadis. The Slonta Limestones, coutaining occasional 

 shelly horizons, form the surface of the plateau. The dip is slight 

 and to the north. A limestone with casts of reef-building corals 

 occurs at the height of a little over 1100 feet, about 7 miles west of 

 our first camp. A short distance farther west we saw exposures of 

 a soft yellowish limestone, which we had the best opportunities of 

 examining in the wells near an Arab burial-ground known as 

 Birlibah. Here I found an echinoid, Hypsoclypeus hemispJiericus 

 (Greg.), the first Miocene 1 fossil found. 



From Birlibah to Gubah, a distance of about 12 miles, the 

 country is thinly wooded moorland. It rises gradually from 1100 

 to 1800 feet ; the rocks are yellowish granular limestones, with 

 some nodular, marly seams, which, especially near Wadi Umzigga, 

 form a number of small springs. The characteristic fossil is a large 

 pecten, which Mr. R. B. Newton has identified as Oopecten rotun- 

 clalus (Lam.). The fossil mollusca collected at the "Wadi Umzigga 

 and seen at other adjacent exposures, indicate that these limestones 

 are not lower than Aquitanian ; and, according to Mr. Chapman, the 

 limestone at Wadi Umzigga is full of Lepidocyclina elepliantina 

 Mun.-Ch., and is Aquitanian or Stampian. The age of the Wadi- 

 Umzigga beds may, therefore, be regarded as Aquitanian. 



At Gubah, beside the ruins of a Greek bath, we found some 

 fossils, among which Mr. Newton identified Strombus coronatus 

 Defr., Alectryonia plicatula (Gmel.), and the cirriped Balanus con- 

 cavus Bronn. He therefore assigns the rock to the Upper or Middle 

 Miocene. After leaving Gubah, we ascended another platform about 

 100 feet high, formed of a rough-weathering limestone ; but, as we 

 were passing close beside a Senussi settlement, Zawiah Charrah, 

 we had no opportunity of collecting fossils until 6 miles from. Gubah, 

 when we reached the ruins of the Roman town of Lamludeh (the 

 ancient Lebdis). There we found some casts of lamellibranchs aud 

 a large gastropod, weathered out of beds of earthy limestone and 

 marl : these fossils, according to Mr. Newton, indicate an Aquitanian 

 age. West of Lamludeh the ground is rocky, and much of it is 

 covered with scrub growing in the depressions between hummocks 

 of a hard, white limestone, containing many large Ostreids, including 

 Ostrea crassicostata Sow. Immediately west of Zawiah Turt is an 

 exposure of a limestone containing many echinoid plates and fora- 

 minifera, and an associated limestone yielded an Amphiope. 



At Labruk, 10 miles west of Lamludeh, the earthy limestones, like 

 those at Lamludeh, crop out north of the track ; close beside the 

 water-hole is a band of hard limestone containing casts of reef- 

 building corals. About half a mile west of Labruk is a bed con- 

 taining many specimens of Ecliinolampas. 



A waste of rocky scrub and rough hills of coral-limestone, with 

 the Echinolampas Bed cropping out in the depressions, extends 

 for 6 miles from Labruk to the marabut or shrine of Sidi Dia- 

 1 For the accepted limit of the Miocene, see p. 593. 



