Vol. 67.] THE GEOLOGY OF CYRENA1CA. 591 



The divide between the Wadi Hamema and the plain of Merj, 

 at the level of about 1100 feet, is formed by some shelly lime- 

 stones from which Mr. Newton has identified the Miocene Anadara 

 turonica : whence we may infer that the Apollonia Limestones, 

 which are exposed in some dry cisterns, are overlain by Miocene 

 beds. The simplest explanation of the occurrence of these beds in 

 this position would be that they were deposited unconformably 

 upon the Apollonia Limestones ; but I saw no evidence of their 

 actual relations. 



The cherts are also exposed on the northern slopes of the divide, 

 between it and the Pleistocene loams of the plain of Merj. Some of 

 the shelly beds near the pass may belong to the Slonta Limestones, 

 which are certainly exposed at Merj, as shown by both mollusca 

 and foraminifera. 



The Priabonian or Slonta Limestones occur at the wells of Merj 

 at the level of only 850 feet, while the Derna Limestone rises in 

 the face of the plateau 2 miles to the south to the height of 

 1240 feet. The Slonta Limestones at Merj must, therefore, have 

 been lowered either by a fault or by a sharp fold ; and the general 

 evidence is clear that the movement was a fault. 



(g) Merj to Benghazi. 



The journey from Merj to Benghazi being hurried, there was only 

 time for a general determination of the rocks close beside the 

 route. The track crosses the Merj alluvium for 2| miles to the 

 south-west and then a low ridge of limestone about 6 miles wide, 

 which separates the plain of Merj from the still larger, but less 

 regular, plain of Silene. This limestone ridge rises to the height 

 of about 1130 feet, or about 300 feet above the plain of Merj. The 

 rock is not well exposed, being covered by a red soil and Thuya- 

 scrub ; but at 4 miles from Merj there are exposures of a limestone 

 with large nummulites, which no doubt belongs to the Derna 

 Limestones, and is continuous with the rocks that bound both 

 sides of the plain of Merj. I could find no chert, except one or two 

 artificial flakes which had probably been carried there. From the 

 summit of this limestone ridge there is a slight fall to the plain of 

 Silene, over which we marched for 30 miles. Its north-eastern 

 part is higher than the plain of Merj ; but it slopes gradually to 

 the south-west, and the outlets of its streams are doubtless in that 

 direction. It is less level than the plain of Merj, consisting rather 

 of undulating steppes covered with a loamy soil, and passing into 

 the limestone downs gradually on all sides, except where it meets 

 the Merj fault-scarp. The surface is wind-swept, and numerous 

 vertical columns of dust travelled across it. The stream banks 

 consist of alluvium, which weathers like loess ; they stand up in low 

 vertical cliffs, and the streams, when they run, are interrupted by 

 small waterfalls. The chief deposit is a brown loam, interstratified 

 occasionally with beds of limestone- gravel. A well at Mletania 

 has been sunk through the alluvium to the depth of 135 feet, and 



