Vol. 67.] THE GEOLOGY OF CYRENAICA. 587 



(d) Slonta to Messa. 



From Slonta we marched northwards up a picturesque dale cut 

 through well-stratified limestones, which are either horizontal or 

 have a dip of about 1° to the north. The rocks included a bed 

 yielding Ecliinolampas, bands with small nummulites. and some 

 containing a large nummulite 2 inches in diameter. We camped 

 beside a Roman fort at Shermatu, and thence descended into the 

 deep ravine of the Wadi Khumas near its head. This wadi descends 

 to the north : its cliffs at first consist of the brown-weathering 

 stratified Slonta Limestones ; but farther north the cream-coloured 

 Derna Limestones, presenting the same characters as at Derna and 

 south of Mersa Susa, appear from beneath the upper series. The 

 Derna Limestone cropped out from the level of 1860 feet in the upper 

 Wadi Khumas down to 1240 feet. As the top of this formation 

 near Mersa Susa, 18 miles away to the north-east, is at 1000 feet 

 above sea-level, the dip of the rocks in this part of Cyrenaica must 

 be 1° downwards to the north-east. 



We descended the Wadi Khumas for 4 miles and left it where, at 

 the level of 1240 feet, it turned westwards ; we rode up a tributary 

 gully on to the Messa plateau. The top of the cream-Goloured 

 Derna Limestone in this gully is at a little over 1300 feet, and the 

 brown stratified Slonta Limestones, containing mollusca identified 

 by Mr. Newton as Lucina cf. pJiaraonis Bellardi, Mactra cf. 

 fourtaui Cossm., and Cardita cf, acuticostata (Lam.), extended from 

 that level to the summit at 1640 feet. Our path joined the main 

 track from Cyrene to Messa near a well, at the height of 1520 feet, 

 in a stratified limestone which contains some clay and flattened 

 stems, and thus resembles the impermeable layer of the Fountain of 

 Apollo. The adjacent limestones yielded Echinolamjpas chericherensis, 

 a species characteristic of the upper part of the Slonta Series. 

 Thence we crossed a rough limestone-ridge and descended to Messa, 

 where there are several springs produced by the laminar limestone 

 with stem-like fragments. Owing to lack of time, I was unfortu- 

 nately unable to continue the section from Slonta through Messa to 

 the coast. 



(e) Messa to Merj. 



At Messa we joined the track from Cyrene to Benghazi. The 

 wells at Messa are among the most important in Cyrenaica. They 

 lie on the floor of a deep valley, and are maintained by drainage 

 from the limestone around. The supply seems to be unfailing, and 

 is sufficient for the irrigation of some gardens. The adjacent ruins 

 show that the wells were important in ancient times. On leaving 

 Messa we climbed on to the plateau, and crossed for 3 miles 

 scrub-covered limestone moors to the shrine of Abdul Wahil. 

 Thence we descended a steep path into a tributary of the Wadi 

 Jeraib (or Wadi Ishgerib, or Jerib), and we followed the tributary 

 until it joined the main valley. The cliffs of the Wadi Jeraib are in 



Q. J. G. S. No. 268. 2s 



