FORMATION OF SPRINGS. 153 



While tbis increase in drainage waters is the general tendency of the 

 forest cover, geological stratification may be so favorable to drainage 

 (deeply fissnred vertical or tilted-np strata) that on the score of per- 

 colation at least the effect may become irrelevant, or it may be so 

 unfavorable (horizontal unfissnred strata) that the intiuence upon per- 

 colation may become practically of small value. 



While underground, one i)art of the filtered water becomes station- 

 ary as soil moisture retained in the capillaries of the soil, and finally in 

 part to be returned to the air by transpiration from the foliage and 

 evaporation from the surface of the soil. The other part — the surplus 

 above the water capacity of the soil — continues to filter through the 

 soil, gathering into definite channels, collecting in beds or basins, and 

 finally reappearing as springs. It is obvious that the first part can not 

 be more than the water capacity of the entire soil layer, unless there 

 be standing ground water which would replenish the loss by transpira- 

 tion and evaporation, sustained by the soil moisture. 



Now, by reasoning from the statements regarding the greater ease of 

 percolation in soils kept granular under the protection of a forest-floor, 

 as well as by the experiments regarding water conductivity and water 

 capacity of soils under varying conditions, and regarding actual meas- 

 urement of filtration waters from such soils, we are forced to admit 

 that in general the quantities remaining for underground runs are not 

 only larger in the first place, but remain so during their subterra- 

 nean existence, suffering less loss by evaporation under the forest cover. 

 This effect, especially apparent on shallow soils, will be more sensible 

 the further away from the catchment basin the water reappears as 

 a spring, that is, the longer the subterranean run. 



FORMATION OF .SPRINGS AND CONDITIONS AFFECTING THEIR FLOW. 



Finally we come to a consideration of the conditions which determine 

 the final reappearance of the underground drainage in the springs. 

 The place where a spring appears is, of course, i)rcdicated in the first 

 place by the structure and topography of the soil and rock strata. 

 The question of the location of a spring is, therefore, a dynandcal one, 

 on which the soil cover can have but little influence. Yet even here, 

 an indirect influence may be found in the amount of water to be 

 drained, and in the looseness of the surface soil, both of which c()udi- 

 tions would tend to ])roduce more numerous outlets and a wider distri- 

 bution of reappearing underground waters. 



The following elementary explanation of the formation of si)rings 

 may serve to show how geological conditions influence to a large ex- 

 tent the manner in which the wateis falling on the watershed are dis- 

 tributed in undergiound channels, collected and discharged, and that, 

 in spite of favorable forest conditions, a region may be poor in springs 

 and that, without any disturbance of the forest cover, a change in the 

 location or even in the run of springs may occur. 



