EASTERN OYSTERS. 



I. How THEIR California Home was Prepared. 



HE water of San Francisco Bay is 

 quite deep in the central portions, 

 but along the edges there are 

 extensive mud-flats. Parts of 

 these flats are exposed to the 

 air as often as the tide falls 

 even a moderate amount; and 

 whenever there is an unusu- 

 ally low tide, hundreds of 



acres of the dark, muddy surface may be seen by 



any one who walks along 



the shore. 



The material from which 



these mud -flats have been 



constructed has largely 



been brought down from 



central California by those 



muddy rivers, the Sacra- 

 mento and the San Joaquin. 



These, in their turn, have 



received their load from 



REFERENCE TOPICS. 



San Francisco Bay. 

 Rivers of California. 

 Placer-mining. 

 Results of mining:. 

 Crossing the bar. 

 Puget Sound. 

 Transcontinental r 



roads. 

 Canned oysters. 

 Destructive flslies. 

 Cattle-raising. 



ail- 



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