CLASSIFICATION OF SPRINGS 



551 



table is about 20 feet higher than on the downstream side. Two 

 ponds fed by ground water lie east of the fault. They are fault 

 dam springs. 



C. SPRINGS IN POROUS ROCK BETWEEN IMPERVIOUS ROCK (aRTESIAN SPRINGS) 



Where water is contained in the pore spaces of a peryious bed 

 lying between impervious strata, the essential conditions for the 



D. Fracture artesian soring 



Fig. 18.— Diagrams illustrating four classes of artesian springs: a, dip artesian 

 springs; h, siphon artesian springs; c, unbedded artesian springs; d, fracture artesian 

 springs. 



existence of springs are that a part of the porous bed outcrop so as 

 to absorb rain in order to provide a regular supply of water, and 

 that the beds be inclined — in other words, the essential conditions 



