THE GEOLOGY OE EGYPT. 409 



wards beyond the Balah Lakes ; from here to Jebel 

 Geneffeh and the middle of the Bitter Lakes, we have, 

 recent fluviatile deposits of the Nile ; while between these 

 and Suez are recent deposits of the Red Sea. Immediately 

 surrounding the Bitter Lakes there are recent deposits 

 containing an impoverished Red Sea fauna. 



Fraas (11) states that Miocene beds are developed at 

 Shaluf (which lies on the Suez Canal some four miles south 

 of the Little Bitter Lake) ; and this might be supposed to be 

 the remains of an isthmus already existing in Pliocene times. 

 But Fuchs definitely asserts that there is no Miocene present 

 there, or anywhere else along the course of the Canal. 



Intrusive and volcanic rocks. — Intrusive dykes of diorite 

 and similar rock appear to be common in the crystalline 

 rocks ; but among the sedimentary deposits eruptive rocks 

 of any kind are very rare. Lyons mentions a mass oi 

 olivine dolerite intruded into the Nubian Sandstone at 

 Jebel Burka, about 20 m. W.N.W. of Wadi Haifa (16). 

 In the oasis of Baharia a basaltic rock breaks through the 

 Cretaceous Sandstone and forms the caps of some of the 

 hills ; but what its relations are to the nummulitic rocks 

 does not appear. It has been examined by Zirkel and 

 found to be an olivine basalt (34). A very similar rock, also 

 an olivine basalt or dolerite, has been described by Arzruni 

 (2) from Abu Zabel on the Ismailia Canal where it is 

 erupted through Tertiary strata. 



In the Wadi Araba a number of small intrusions of 

 basaltic rock have been discovered by Schweinfurth and 

 Walther (32). 



Lastly Mayer-Eymar (19) has found a bank of dolerite 

 resting upon Lower Tongrian beds in the hills ot the 

 Kum-el-Chachaf. He believes these and the igneous 

 rocks of Baharia and Abu Zabel to have been erupted at 

 the same time, that is to say, at the close of the Lower 

 Tongrian period. If this be so, it is not unlikely that the 

 hot springs which caused the silicification of the Jebel 

 Ahmar Sandstone and of the Petrified Forests, represent 

 the close of the only period of vulcanicity which there has 

 been in Egypt since, perhaps, Archaean times. 



