Vol. 67.] THE GEOLOGY OF CYRENAICA. 607 



too of Abu Shaifa Bay and Kanais Bay, are also due to faults. The 

 abrupt western ending of Crete along a north-and-south line, and 

 the conspicuous headlands with the same trend, such as Cape 

 Littinos and the western shore of the Gulf of Morabella, may also 

 be due to north-and-south faults. (See map, fig. 4, p. 604.) 



The throw of some Cyrenaican faults is very great. The fault 

 behind Mersa Susa had a movement of approximately 1500 feet, and 

 the Tokra fault had a downthrow to the west of at least the same 

 amount. The movements, though extensive, are probably of recent 

 geological date. The best evidence obtained as to their age is from 

 the Tokra scarp. Limestones with Cerastoderma edule extend over 

 the coastal plain nearly to the foot of that scarp. I did not see 

 them along the fault-line, but their range inland was probably 

 bounded by it. As the C.-edide Beds are late Pliocene or early 

 Pleistocene, the fault-scarp was probably formed before the deposi- 

 tion of these beds ; it was certainly later than the Scutella Limestone, 

 which is probably of Middle or perhaps Upper Miocene age. 



The faults are not necessarily of one age, but they were probably 

 all part of a connected series of movements which apparently began 

 later than the Helvetian and earlier than the Cerastodcrma-edule 

 Beds. These deposits represent a marine transgression of late 

 Pliocene and early Pleistocene age, which can be recognized in many 

 widespread localities on the northern coasts of Africa. If the Tokra 

 scarp be a continuation of that in Western Crete near Kanea, the 

 south-west to north-east faults would be earlier than those which 

 trend east and west and have determined the northern coast of 

 Cyrenaica ; and the fact that we did not find the Cerastoderma-eduU 

 Beds along the northern coast gives slight support to that hypothesis. 

 Negative evidence from a hurried examination of so small a propor- 

 tion of the coast is of little weight, but the fact may be mentioned 

 in order to direct attention to this point. The Cerastoderma-edide 

 Beds occur on the western coasts of Egypt ; and, if they are 

 absent from the northern coast of Cyrenaica, then the faults, by 

 which the last remnant of the land-connexion between Africa and 

 Crete foundered beneath the Mediterranean, took place after the 

 deposition of the early Pleistocene limestones. The land-bridge to 

 Crete would moreover have been limited in width to the area 

 between Ptolemeta and Mersa Matruh, where M. Pachundaki has 

 found the C.-edule Beds. 



Cerastoderma edule is widely distributed in Algeria and Tunisia, 

 and is referred by M. Georges Holland 1 to the Upper Pliocene; but, 

 as its main distribution is post-Sicilian, it is safer to regard the 

 C.-edule Limestone in Cyrenaica as early Pleistocene, the age 

 accepted for it by Dr. Blanckenhorn 2 and by M. Pachundaki. 3 



1 ' Geologie du Sahara Algerien & Aper<ju geologique sur le Sahara, de l'Ocean 

 Atlantique a laMer Rouge.' Chemin de FerTranssaharien (French Government 

 Report), Paris, 1890, pp. 194-95. 



2 ' Neues zur Geologie & Palaontologie jEgyptens — IV. Das Pliocan- & 

 Quartarzeitalter ' Zeitschr. Deutsch. Geol. Geselisch. vol. liii (1901) table 

 facing p. 308. 



3 ' Contribution a l'Etude Geologique des Environs de Marsa Matrouh 

 (Marmarique) ' Revue Internationale d'Egypte, vol. iv (1907) pp. 4 & 6. 



