120 foley. SEDIMENTATION AND GROUND WATER [Ch. 6 



Outwash plains, eskers, kames, and kame terraces all form important 

 aquifers. The extensive outwash plains off the front of the Wiscon- 

 sin end moraines in Wisconsin are good examples. In the Antigo area 

 in northern Wisconsin the outwash plains furnish much water for 

 municipal, domestic, and irrigation use. The problem of locating sup- 

 plies of water from glacial deposits is a special field which requires 

 a thorough knowledge of glaciology. 



CONTINENTAL ENVIRONMENTS— FLUVIAL 



Piedmont Environment 



Some of the sediments deposited on piedmont slopes are important 

 aquifers. In much of the basin-and-range country of the southwestern 

 United States they, and sometimes associated desert deposits, are the 

 only source of ground water, and frequently the only source of water of 

 any kind. 



Most piedmont sediments, however, are not good aquifers, for they 

 are formed principally by sudden floods, which deposit large quantities 

 of relatively coarse, blocky material, and in turn are overlain by finer 

 sediments that clog the openings, making them relatively impermeable. 

 Most of the good aquifers seem to be stream deposits of sand and 

 gravel formed during times of rather quiet flow in and near the stream 

 channels themselves. Such deposits are very heterogeneous in dis- 

 tribution and are difficult to correlate, even for short distances. 



Many of the aquifers crop out along the upper edges of the piedmont 

 slopes and so receive annual recharge, whereas others receive recharge 

 by slower percolation of the water from less permeable materials sur- 

 rounding them. Coarse talus material near the upper edges of the 

 piedmont slopes may allow much water to reach the sand or gravel 

 aquifers that transmit it toward lower areas. In most piedmont areas, 

 ground water obtained at lower elevations is under artesian pressure, 

 and flowing or near-flowing wells are common. 



An example of ground water in piedmont areas is that in Tooele 

 Valley, Utah, described by Thomas (1946). Many other areas in 

 southwestern United States have been studied by the U. S. Geological 

 Survey and its cooperating agencies and the results have been pub- 

 lished. 



The Valley-Flat Environment 



Included here are sediments deposited in stream channels as well 

 as on the flood plains of streams. The character of the sediments 



