588 PROF. J. W. GKEGORY ON [Nov. I9H, 



places almost vertical, and they consist in part of the cream-coloured 

 Derna Limestone. Farther down the wadi the cliffs increase to the 

 height of about 400 feet, and the Derna Limestone is doubtless 

 capped by the Echinoid Limestone, as fallen blocks of this rock lay 

 at the foot of the cliff. We descended the Wadi Jeraib to the level 

 of about 820 feet, when it bent round to the north-east. 1 There 

 was no sign, even in the lowest part of the wadi, of the chert- 

 bearing limestones. Leaving the main valley, we ascended a 

 tributary to the south-west ; we crossed the Echinoid Limestone 

 above the Derna Limestone, and reached the surface of the plateau 

 in front of the Homan castle, Gasr el Migdum. A limestone com- 

 posed of reef-building corals crops out beside it, and on the west of 

 it is a limestone containing small quartz-pebbles. The rocks in this 

 area and for some distance westwards include more mechanically 

 derived sediment than those farther east, and the ground is often 

 covered by a white residual clay. Erom Gasr el Migdum we 

 marched for 30 miles over an undulating limestone-plateau ; the 

 original surface varied in level from 1400 to 1500 feet, but it has 

 now been dissected, by the excavation of numerous valleys, the 

 floors of which are at the level of 1200 or sometimes of 1100 feet. 

 The country is a wilderness of scrub, which became denser as we 

 approached the Wadi Gharih. 2 The few fossils found included a 

 large gastropod from below the shrine of Sidi Abdullah, identified 

 by Mr. R. 13. Newton as Hippoclirenes ampla (Sol.), which we also 

 found on the plateau south-east of Messa. This fossil and an occa- 

 sional Echinolampas show that the rocks are of Upper Eocene (Pria- 

 bouian) age. The last Echinolampas was found 6 miles east of 

 the Wadi Gharib; but, as in that district we were marching in single 

 file through dense scrub, we could not make any effective search for 

 fossils. The valley of the Wadi Gharib shows fine sections of 

 stratified foraminiferal limestones, resembling those of the Slonta 

 Series. The rock-exposures, however, were covered with a crust of 

 efflorescent limestone, and when this layer was broken through the 

 fossils seen were indeterminable casts ; but it was dark before there 

 was an opportunity of searching the rocks, and we had to resume 

 our march at dawn next morning. 



We continued across the plateau of scrub-covered limestone, until 

 we reached an alluvial plain at Bigratah or Bugrat ; the hillsides 

 around the plain consist of the cream-coloured Derna Limestone 



1 The Admiralty Chart represents this wadi as part of a basin of interna 

 drainage, and separated from the sea by a continuous ridge from Messa to Gasr 

 el Migdum. Judging from the levels, the Wadi Khumas probably joins the 

 Wadi Jeraib above the confluence with the wadi from the shrine of Abdul 

 Wahil, and both should discharge northwards ; otherwise, it seems improbable 

 that the route should descend into the Wadi Jeraib, instead of keeping on the 

 plateau to the north of it. 



2 We were assured that there was no water between Messa and Merj, except 

 for some small wells in the Wadi Gharib. The Commandant of the Turkish 

 garrison at Messa kindly sent a camel laden with water with us to Gasr el 

 Migdum, to save us from drawing on our own loads. The few Arabs remaining 

 in this district were said to live on scanty supplies of stored water. 



