1902.] AND ANCIENT GEOGRAPHY. 369 



valley. 1 The latter and the Red Sea originated in the Pliocene. 

 Into the Nile valley entered the Pliocene Mediterranean Sea. It 

 then changed into a series of inland lakes, and finally, in the 

 middle Diluvial time, it became a river valley. The depression of 

 the Red Sea was occupied first (Pliocene) by inland lakes, and 

 finally, toward the end of the P'iocene, by the Indian Ocean, 

 which entered it from the south. 2 The present separation of Africa 

 and Arabia (Asia), which is nearly complete, belongs, therefore, to 

 a very recent date. In the later Tertiary Southern Asia and Africa 

 were not distinguished zoogeographically, while in older times 

 (Pre-Miocenej there was a complete separation of Africa (including 

 Arabia) from the Sinic continent, and only during the second half 

 of the Cretaceous was there a limited connection by way of Mada- 

 gascar and the Indian peninsula. 3 



The old isolation of Africa was ended not only in these eastern 

 parts during the Tertiary, but also in the northwest changes 

 occurred which extended Africa and brought it into contact with 

 Western Europe. 



The Cretaceous sea covering Northwestern Africa was no doubt 

 considerably reduced in the Tertiary. Indeed, there are Tertiary 

 deposits in this region, and according to Suess (1888, p. 155), the 

 Middle Tertiary sea probably also covered the Western Sahara. 

 But about this time apparentlva land connection was formed to the 

 north toward the old Spanish Meseta. According to Bergeron, 4 

 the Algerian Sahara possesses deposits from the Senonian to the Plio- 

 cene, but these are bounded in the west by a Cretaceous mountain 



1 In the region of the Nile valley there was a river, but this was not the Nile, 

 but came from the west out of the Libyan desert. 



2 An actual connection of the Red Sea and the Mediterranean Sea is very 

 doubtful, but was possibly established for a short time in the beginning of 

 Diluvial times, when the Mediterranean Sea became cold. The improbability 

 of a connection of both seas is especially emphasized by Jousseaume (Ann. Sei. 

 Nat., Ser. 7, Vol. 12, 1891). According to hiai, the Red Sea is Quarternary 

 (Diluvial). 



3 The oceanic connection from the Gulf of Aden across the Sahara desert to 

 the Atlante (Senegambia), advarced by Jousseaume (/. c ), has no geological 

 support. It is founded upon an alleged similarity of the Mollusk faunas of both 

 parts which, however, needs closer inves igation and might possibly find its 

 explanation in the configuration of the Pre-Mioceue Tethys, which reached fron» 

 the Persian Gulf to the Mediterranean Sea and Atlantic Ocean. 



4 In Mem. Soc. Ingen, civ. France, 1897. 



