322 THE DEEP SEA 



and even more valuable when used in conjunction with C'^ and 

 with each other. 



3, Isotope methods are best for large-scale problems. Mixing 

 within given masses of water is in many cases apparently too rapid 

 to give rise to appreciable concentration differences. In this respect 

 the method nicely supplements the deep float method which 

 yields considerably more detailed information in local areas. 



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