Geological Society. 649 



ifarch 8th, 1911.— Prof. W. W. Watts, Sc.D., M.Sc.j F.R.S., 



President, in the Chair. 



The following communication was read : — 



' Contributions to the Geology of Cyrenaica.' 

 By Prof. J. W. Gregory and others. 



(i) The Geology of Cyrenaica. By John Walter Gregory, 

 D.Sc, F.R.S., F.G.S., Professor of Geology in the University 

 of Glasgow. 



According to the scanty evidence available in 1908 regarding 

 Cyrenaica, which Hildebrand described in 1904 as ' heute noch 

 so gut wie unbekannt,' the country might be interpreted as a 

 fragment of a mountain-loop, an off-branch from the Atlas, or as a 

 plateau of Miocene rocks. 



In a journey across the country, the Author found that it was 

 a plateau of Lower Kainozoic Limestones, which are classified as 

 follows : — 



Oligocenk Ojrene Limestones. 

 (Aquitanian) 



ISlonta Limestones = Priabonian. 

 Derna Limestones = Moqatlam Series of Egypt. 

 Apollonia Limestones = Libyan Series of Egypt. 



Some Miocene limestones occur in places on the plateau, and lying against 

 its western foot. 



These rocks are all limestones, containing very little clastic 

 material. They must have been deposited in a clear sea, at depths 

 ranging down to nearly 1000 fathoms. 



Intervals of shallow sea are indicated by some limestone-con- 

 glomerates and a band of coral-reef limestone. The country was 

 uplifted in later Miocene times, and was then part of a wide land 

 which included Crete and occupied the site of the ^gean Sea. 

 This land was broken up by great subsidences, which left Cyrenaica 

 as a horst bounded by fault-scarps on the north and west. 

 Eastwards the country sinks by a slight dip and a succession of 

 faults, until the Miocene limestones, which occur on the plateau 

 in Cyrenaica, are at sea-level on the coasts of Western Egypt. 

 Cyrenaica may thus be regarded as part of the western limb of 

 the geosyncline of Western Egj-pt. 



The formation of the river-valleys probably began during a period 

 of wetter climate than the present, but there is no evidence of any 

 appreciable change in the climate or water-supply since the date 

 of the Greek and Roman colonization. 



Ann. & Mag. N. Hist. Ser. 8. Vol. vii. 43 



