552 LIFE AS RELATED TO PHYSICAL CONDITIONS 



coast line and harbors of Greece shows one cause of its 

 ancient civilization and a reason why the Greeks were 

 " always seeking some new thing." 



SUMMARY 



Physical conditions have a great effect on the distribution 

 of life upon the earth. It is hard for living things to cross 

 high mountains, broad oceans, or vast deserts. When con- 

 fined to certain climates and areas, plants and animals 

 naturally adjust themselves to these. 



Life in the sea is so simple that plants and animals there 

 are not forced to become as highly developed as are those 

 of the land. On land there are greater ranges of climate 

 and other physical conditions, so that plants and animals 

 have been forced to a high development in order to survive. 

 Man is one of the greatest forces at present affecting land 

 life. He transplants and transports animals and plants 

 according to his desires. The physical conditions decide 

 whether or not they shall live. 



The elevation of mountain regions, difficulty of travel, 

 and lack of agricultural lands cause these sections to be 

 sparsely settled by backward peoples unless mining has 

 attracted progressive settlers. Mountains have always 

 furnished safe retreats for persecuted peoples and have been 

 barriers to further conquest. 



Life on the plains is usually most varied. But since the 

 plains offer no safe retreat, the inhabitants of level lands 

 have always been subject to invasion and conquest, and the 

 native animals to extermination. Coastal plains offer no op- 

 portunities for mining, but certain kinds of manufacturing and 

 agricultural pursuits are peculiar to such regions. Access to 



