OCR Text |
Show The benches and mesas are prominent features and they are also important agriculturally. Soils on these lands are derived from old alluvial materials. While the recent alluvial lands include the valleys of the more important streams such as the Duchesne and Strawberry Rivers, a considerable number of small intermittent stream tributaries flow through narrow valleys. Each of these has developed a small strip of sloping alluvial lands that widen out into small alluvial fans at their confluence with the larger streams. The Unit lands of the Uinta Basin or Duchesne River area are found mainly on these alluvial materials. Most of the soils of the area are low in organic matter and nitrogen but are high in minerals. The color of the dry surface soil ranges from light brown to pale brown. Various limitations cause much of the land area within the Unit boundaries to be unsuited to crops. In many large areas the soils are extremely shallow or thin over cobble rock, a hardpan of lime carbonate, or bedrock. Some soils have unfavorable relief or have erosion problems, and in many areas poor drainage, and the accumulation of soluble salts limit the suitability of some soils for production of crops. All soils of the area are calcareous, having been developed in a semi- arid to arid climate. They are youthful with little or no development, having undergone little, if any, change by weathering since they were deposited. Alkali salts exist to some extent in nearly all the soils of the area; but excessive alkaline conditions are mainly the result of lack of drainage, seepage, or improper irrigation practices. Pre- Unit condition can be approximated by observation of undeveloped lands lying above existing canals. On the well- drained uplands the native vegetation consists of sagebrush, greasewood, rabbit brush, and shadscale, with rank or good growth characteristics occurring in areas of higher rainfall. The shadscale lands typify the low rainfall or desert areas. On the rough broken lands that comprise the bulk of the area . weathering and erosion rapidly deposit the soil materials as alluvium. Any patches of arable soils in these areas were usually thin, rough in topography and small in extent, and usually inaccessible to irrigation water. ( 2) Bonneville Unit Lands Permanent non- Indian settlement did not take place until after 1905 when the area was opened to the Homestead Act. 160 |