I attached a picture of the layers of the earth.  They are the:
Crust (<em>which isn't really the interior</em>)
Mantle
Outer Core
Inner Core
 
        
        
        
So your point doesnt become invalid.
        
                    
             
        
        
        
Answer: EVAPORATION. 
Explanation: Salinity can be defined as the saltiness or the concentration of salt dissolved in a body of water. Measured in grams of salt divided by the kg of water. 
Evaporation increases the salinity of water. Basically, evaporation is the process of converting liquid into gaseous state. In essence, concentration of a solution can be increased by evaporation and since the salinity of water is measured in grams of salt divided by the kg of water, therefore, the lesser the amount of water per salt, the higher the salinity. 
 
        
             
        
        
        
Desert and Rainforest, I believe this could the right answer
        
             
        
        
        
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