524 KIRK BRYAN 



and on these factors the classification outlined in this paper has 

 been based. Temperature, dissolved salts, contained gases, rate 

 and amount of flow, form and position of the spring opening are 

 all characteristics of springs, which, while in'Tnany cases related 

 to genesis, vary among springs of the same origin. It has seemed 

 best to first divide springs into two groups based on charac- 

 ter of the water and make further subdivisions on structural 

 grounds. 



In the use of this classification difficulties will arise which are 

 of two types. In the first place, the local structure in the vicinity 

 of springs is difiicult to determine, for the presence and passage of 

 water facilitates weathering and destroys the evidence. The 

 presence of luxuriant vegetation also tends to conceal the structure. 

 Whatever the difficulties of determining the structural relations 

 and origin of the water for single springs, the study of groups of 

 springs will usually be successful. The second difficulty arises 

 through various combinations of structures which may combine 

 to produce a spring. The structure which plays the predominating 

 role should then determine the classification of the spring. The 

 common sense and judgment of the investigator will lead him to the 

 proper decision, but his labor will be easier if he remembers that 

 ground water moves through three dimensions, though our con- 

 ventional methods of illustration show but two. Springs of diverse 

 origin may, however, have peculiarities so remarkable or inter- 

 esting as to justify their grouping under a common name. The 

 proposed system is not intended to supplant the use of such descrip- 

 tive terms as blowing springs and thermal springs, but to provide 

 a series of terms expressive of genesis which will include all springs, 

 particularly those now called, for want of a better term, "common 

 springs." 



ACKNOWLEDGMENTS 



In preparing this paper the writer has profited by the kindly 

 criticism of members of the Ground-Water Club of Washington, 

 D.C. The late Professor Joseph Barrell and Professor Herbert E. 

 Gregory offered helpful suggestions. The writer wishes to acknowl- 

 edge his special obligations to Dr. Henry Hollister Robinson for his 

 generous help in methods of expression. 



