70 



FIBST TEAB SCIENCE 



port of Los Angeles, California. Suess, the great Austrian 

 geologist, thinks that the great changes of level between the 

 sea and the land are due to a rising and falling of the sea 

 and not a rising and sinking of the land. However this 

 may be, there have been marked changes of level between 

 the two and the boundary between sea and land has been 

 a varying line. Sea and land areas have frequently inter- 

 changed, although deep sea bottoms were probably never 

 dry land. 



38. Characteristics of Land Surfaces. The surface of the 

 land differs from that of the sea in being at least com- 



OLD ROCK BEACH, IMPERIAL VALLEY, CALIFORNIA. 

 Formerly part of the coast Hue of the Gulf of California. 



paratively immovable. It is rough and irregular, and is 

 composed of many different kinds of rocks and soils. For 

 the larger part of its area it rises above the level of the sea, 



