CHAP. IX.] JURASSIC PERIOD. 147 



they would quickly spread over a large area in Central Asia 

 which is now for the most part a dry and sandy desert. I 

 do not mean to infer that anything like a cataclysmal in- 

 flux of water would take place; the first inroad would 

 doubtless occur during the prevalence of a strong west 

 wind, 1 and would be only a temporary invasion, but as 

 submergence went on, such invasions would be of frequent 

 occurrence, till at length a permanent connection was 

 established. 



Two important results would follow from such a change : 



(1) large numbers of the creatures living in the Caspian 

 would be immediately killed unless they could support the 

 changed conditions of water and food ; if destroyed, their 

 remains would doubtless be laid out, and stratified, as it 

 were, on the bottom of the sea, thus forming bone-beds. 



(2) The climate and appearance of the surrounding country 

 would be gradually altered ; evaporation from the newly- 

 created sea would give rise to the formation of clouds ; these 

 would fall again as rain on the neighbouring hills ; rills and 

 rivers would come into existence, and the ordinary processes 

 would be set in action ; the country would be irrigated and 

 fertilized, and the products of erosion would be washed 

 into the widening sea. A scene of death and decay, desert 

 wastes and slowly shrinking lakes would be converted into 

 a sea full of active creatures, bordered by a region where 

 the plash of waters and the hum of insects were unceasing 

 sounds. 



Such must have been the change which ensued when the 

 Bhaetic waters filled the basins of the Triassic lakes. The 

 bone-beds testify to the suddenness of the invasion and the 

 inability of the Triassic fish and reptiles to survive the 

 change. 



The fauna of the succeeding shales and limestones suggests 



1 If there were tides in the Black Sea, it would occur when there was 

 an unusually high tide. 



