Vol. 67.] THE GEOLOGY OF CYREDTAICA. 583 



siasia (or Sidi Jaja). From our camp there we visited Safsaf, 

 some bare limestone-hills used by the Romans as a collecting-ground 

 for water, which was carried by an aqueduct to the city of Gyrene, 

 6 or 7 miles distant in a direct line. The same hard Slonta Lime- 

 stones, which weather irregularly, occur north-west of Sidi Eof 

 Diasiasia ; they pass in that direction under a series of soft, earthy, 

 white and grey limestones and marls. These rocks form the hills 

 over which are scattered the widespread ruins of the city of 

 Cyrene. The rocks agree lithologically with those of Lamludeh 

 and the fossils collected show that the Cyrene Limestones are of 

 Aquitanian age. 



(c) Mersa Susa (Apollonia) to Slonta. 



It was necessary for our work to determine the conditions which 

 control the water-supply of the district near Cyrene and the chances 

 of finding situations suitable for storage-reservoirs. Hence we 

 made a north-and-south traverse across the country from the sea at 

 Mersa Susa (Apollonia) through Cyrene, to the southern downs at 

 Slonta. This section (fig. 3, p. 584) illustrates the general geological 

 structure of that part of Cyrenaica. 



The city of Cyrene stands at the height of about 1950 feet above 

 sea-level, on the northern edge of a plateau which rises gradually 

 southwards to 2700 feet near Slonta. Immediately north of Cyrene 

 is a steep cliff, which falls to the level of about 1300 feet, whence 

 a platform, generally referred to as the ' lower plateau/ extends 

 for about 3 miles northwards, and from its edge, at the height of 

 about 1000 feet, the steep lower cliff falls abruptly to the shore. 

 The lower cliff, being the extension of the cliff near Mersa Susa, 

 may be a fault-scarp ; it was, therefore, necessary to consider 

 whether the upper cliff at Cyrene was of the same origin. This 

 view appeared the more possible, as a little below the Fountain of 

 Apollo is a white soft limestone, containing nummulites indis- 

 tinguishable in the field from those in the similar rock of the 

 Derna Limestone, which is exposed in the upper part of the lower 

 cliff. I could, however, find no repetition of the Echinoid Lime- 

 stone, which overlies the Derna Limestone, above the upper nummu- 

 litic limestone, and was accordingly forced to reject the possibility of 

 the two similar nummulitic limestones being the same bed repeated 

 by faults. This conclusion is supported by Mr. Chapman's identifi- 

 cation of the characteristic foraminifer of the upper limestone as 

 Nummulites gizehensis var. lyelli ; while that found in the Derna 

 limestone is the typical form of the species. The upper cliff 

 moreover, has the characters of an escarpment, and not of a fault- 

 scarp : it has been cut back into numerous gullies, and projects 

 between them in irregular spurs. The uneven escarpment-like 

 weathering of the cliff is well shown in the plan of Cyrene by 

 Smith & Porcher. 1 



i R. M. Smith & E. A. Porcher, 'History of the Eecent Discoveries at 

 Cyrene ' 1864, pi. xl. 



