CLASSIFICATION OF SPRINGS 



537 



thus include all sorts of side channels, abandoned channels, oxbow 

 lakes, sloughs, and water holes. Springs of this type are exceed- 

 ingly valuable in arid regions. They are frequently made, 

 destroyed, and remade by streams that carry large quantities of 

 sediment. 



B Valley spring 



General level of river flood plain 

 Stream ^ Springy 



D. Border spring 



Fig. 4.— Diagram illustrating four classes of depression springs: a, dimple 

 springs; b, valley springs; c, channel springs; d, border springs. 



Border springs are due to the change in gradient at the Hne 

 between the alluvial slopes and central flat of a desert basin (Fig. 

 ^d). Such alluvial slopes extend from the mountains with a 

 gradually decreasing gradient. This decreasing slope finally merges 

 with a central undrained flat or with the river bottom of a through- 

 flowing stream. Around the edges of such a flat or the river 

 bottom of a through-flowing stream is a line of springs and seeps. 



