IV-31 



evolution of drowned river valleys has progressed farther in the 

 latter regions. 



The two Pacific Coast regions are striking 1n that rivers with 

 drainage only from the coastal mountain ranges carry much greater 

 sediment loads than those which drain the interior ranges. 



CLIMATE 



Solar energy striking the earth sets up complex cycles of water and 

 energy flow from the oceans to the sky and the land and back again. 

 That part of the energy cycle occurring 1n the atmosphere gives 

 rise to the various combinations of weather phenomena which make up 

 local climates. Land, sea, and sky are mutually dependent in pro- 

 ducing specific climates, and the great ocean currents play their 

 Indirect roles in modifying the climates of the estuarlne zone in 

 addition to their direct effects discussed earlier. 



The annual distributions of temperature, precipitation, sunlight, 

 and prevailing winds as well as the total amounts of each are of the 

 greatest significance. Table IV. 1.3 and Figure IV. 1.18 summarize 

 the major climate characteristics in the estuarlne zone of the 

 United States; 



Precipitation may fall as rain, snow, or other forms of ice, 

 depending on temperature; the form of precipitation has not only 

 local impact, but also affects annual patterns of river flow in 



