Soils on Recent Alluvial Fans . The Panoche and Sorrento 

 soil series both occupy extensive recent alluvial fans along 

 the west side. Tile drainage systems are well-represented 

 in these two series. Only a few tile systems are located in 

 the Panhill series and only one system in the Foster series. 



All these soils are closely related in mode of formation. 

 Soil-forming factors have not had time to act upon the soils, 

 which are usually deep and permeable and offer little or no 

 restriction to downward water movement in the upper portions 

 of the soil profile. However, these soils are stratified at 

 lower depths with sand, silt, and clay, the latter two causing 

 perching when they are irrigated heavily. Some evidence of 

 soil formation can be found in the Sorrento and Panhill soil 

 series; little or no soil development occurs in the Panoche 

 and Poster profiles. 



As originally mapped in western Fresno County, the related 

 Panoche and Panhill soils were moderately affected by salt 

 and alkali. This is in contrast to the relatively salt-free 

 Sorrento series. Parent materials from sedimentary sources 

 are mainly sandstones and shales of the Coast Range. 



Sorrento soils, which are located north of Gustine, are 

 slightly darker than are the Panoche or Panhill soils of the 

 central area. This may be due to the greater influence from 

 nonmarine parent materials found in the area (8). 



Soils of Older Alluvial Fans . The Rincon, Ambrose, and Lost 

 Hills soil series occupy older alluvial fan positions in the 

 study area which have developed on valley fill material 

 derived from the same sedimentaj^y sources as recent alluvium. 

 The main bodies of these soils are located short distances 

 from stream channels, but they are free from recent alluvial 

 deposition which has resulted from changes which occurred in 

 the main course of the depositing stream. Soils in these 

 positions have had sufficient time to develop a well-defined 

 subsoil in which clay and lime have accumulated. Permeabil- 

 ity is inhibited but not restricted in the subsurface; 

 however, the subsoils are often stratified and restriction 

 occurs at lower depths. 



The Rincon soil series is genetically related to the more 

 recent Sorrento series in the northern area. These soils 

 are somewhat darker and contain less alkali and other salts 

 throughout the soil profile than does the Lost Hills series 

 of the central area. 



The Ambrose soils normally have fine-textured surfaces and 

 heavy-textured subsoils that restrict the penetration of 

 roots and water. The substratum, which ranges from 30 to 

 60 Inches below the surface, consists of stratified 



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