CONTROLLING FACTORS OF ARTESLIN FLOWS G29 



Sources of Underground Water 



The probable source of underground waters has been widely discussed, and 

 while every one would doubtless agree that by far the greater part is derived 

 from rainfall, there is a considerable variation of opinion as to the relative 

 importance of the other sources, aud especially as to the part played by the ' 

 sea and aqueous magmatic emanations. The conmiou sources of underground 

 waters are as follows : 



List of Sottrces of Uinlen/roiDid Water 



I. Atmosphere. 



A. Direct. 



a. Precipitation. 

 J). Condensation. 



B. Indirect. 



a. Lakes. 

 1). Streams. 

 II. Hydrosphere, or ocean. 



A. Recently or contemporaneously absorbed waters. 



B. Originally included sea water. 

 III. Lithosphere, or crust. 



A. Primary waters. 



Chemically excluded waters. 



B. Secondary waters. 



Physically excluded waters. 

 IV. Centrosphei'e, or interior. 



A. Directly excluded waters. 



B. Indirectly excluded magmatic waters. 



Confining Agents 



In the discussion of the confining agents in artesian systems the materials 

 are divided for convenience into bedded aud Jointed rocks. In the usual dis- 

 cussion the impervious bed is ordinarily the only agent recognized, but the 

 extensive fieldwork which has been conducted by a considerable body of 

 workers for the last three years has brought to light some new agents and 

 emphasized the importance of other seldom mentioned factors. 



List of Confining Agents 



I. Bedded rocks. 



A. Upper confining agents. 



1. Impervious beds. 



2. Stratification. 



3. Friction. 



4. Mineral crusts. 



5. Frost zones. 



