2 SOILS OP THE SUTTER BASIN. 



and mapping soil conditions in such portions of the area. More- 

 over, in the larger proportion of the basin not protected from over- 

 flow or provided with means of drainage and periodically occupied 

 by a large body of water, the soils were not differentiated with the 

 detail upon the map or as closely studied with reference to agricul- 

 tural possibilities as were the adjacent soils now utilized for agri- 

 culture. Subsequently, however, a proposed engineering project of 

 considerable magnitude, involving protection of the lands of the 

 basin by an extensive system of levees and artificial overflow chan- 

 nels and the draining of the lands by installation of pumping 

 plants, has led to a request for further study of the soil conditions 

 within the basin. A revision of the central and southern portion 

 of the basin covered by the project has therefore been undertaken. 



TOPOGRAPHY. 



The surface of the basin lies at an elevation of 10 to 15 feet below 

 that of the recent alluvial soils immediately adjacent to 'the stream 

 channels. It consists of sedimentary deposits laid down by the 

 waters of periodic floods in the streams mentioned, and is of a 

 level plain, save for occasional lagoons or remnants of former 

 stream channels and small isolated knolls. In the vicinity of the 

 streams inclosing the basin and in the apex formed by their junction 

 a den.se growth of timber and brush occurs, but the surface of the 

 basin itself is generally treeless. Large areas are entirely barren of 

 vegetation, while others are covered with a dense growth of tule 

 (Scirpus lacustris) and weeds. 



The soil material covering the floor of the basin is being added to 

 with each successive flood, the annual increment of sediment, amount- 

 ing in localities particularly favorable to its deposition to as much 

 as 2 inches. Except for areas of limited extent protected from over- 

 flow, upon which attempt has in some cases been made to utilize the 

 land for crop production, the soils of the basin have been utilized only 

 for grazing. The lower lying lands are not suitable for this purpose 

 except during the dry season. The soils are predominantly of heavy 

 texture and, in their natural undrained condition, of compact 

 structure. 



Occurring within and immediately adjacent to the portion of the 

 basin covered by the revision of the earlier survey the following soil 

 types, as differentiated in the original survey, were mapped: 



Sacramento fine sand, Sacramento fine sandy loam, Sacramento 

 silt loam, Sacramento clay, and Marcuse clay loam. 

 [Cir.raj 



