MOVEMENTS OF GROUND WATER 



259 



across the alluvial fan built up by the dropping of the stream-trans- 

 ported material. 



Rate of Flow of Underground Water. The following table 

 adapted from Slichter (65 : .?/) shows the theoretical rate of flow 

 and amount of transmission determined by experiment for various 

 kinds of soil, with a porosity of 32 per cent., and at the temperature 

 of 50° F. and with pressure gradients of 1:1, and loq, feet to i 

 mile.* 



Table showing perrueability of various soils. 



Note. — The last figures (o) in the higher numbers are approximate. 



Direct observations on the underflow of water to the Loup 

 River, Nebraska, have indicated a rate of one-third of a mile per 



* The number in italics gives the value just before the upper limit of each 

 grade is reached. Compare table, p. 287, Chapter VI. 



