6 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1907. 



has been eroded by the Sacramento liiver from the stream deposits of 

 days, sands, and gravels laid down at an earlier period in this depres- 

 sion. The valley within the area surveyed is from a half mile to 3 miles 

 in mdth. In the vicinity of the town of Anderson it attains its 

 maximum width and greatest agricultural importance, and it is here 

 known as the Anderson Valley. The Sacramento River, which 

 traverses the area in a southeasterly direction and flows through a wide 

 and generally shallow channel, often marked by riffles formed by 

 gravel bars, is frequently bordered by sand bars and wooded bottoms, 

 or by bluffs sometimes rising to nearly 100 feet in height. The 

 valley bottoms support a vigorous growth of valley oak or a dense 

 covering of cottonwood and sycamore, with an almost impenetrable 

 undergrowth of ''willows," brush, and vines. The adjacent valley 

 slopes are usually dotted with groves or individual oaks and support 

 during the winter and early summer a good growth of nutritious 

 grasses. 



West and southwest of the Sacramento River and its recent valley 

 the survey embraces a comparatively large tract of rolling or sloping 

 plateaulike country, often greatly dissected by streams, and made up 

 of earlier stream deposits from 100 to 200 feet or more above the recent 

 valley floor, from which it is generally separated by well-marked 

 bluffs or terraces. Tliis rolling or elevated plateaulike country 

 extends beyond the western boundary of the area and merges in the 

 foothills of the Klamath Mountains. Its numerous minor stream 

 valleys are generally more or less forested with live and deciduous 

 oaks and digger pines, and are often covered with a dense growth of 

 chaparral consisting of manzanita, coffee berry, and ceanothus. 

 East from Anderson, where this region becomes important agricul- 

 turally, it is known as Happy Valley. The main tributary streams of 

 the Sacramento in this section of the area are Cottonwood and Clear 

 creeks, which traverse narrow valleys and maintain a small flow of 

 water throughout the dry season. The Clear Creek bottoms, as is the 

 case in other parts of the area, have been more or less disturbed by 

 hydraulic mining operations and the stream courses partially filled or 

 obstructed by debris. 



The northern half of that portion of the area lying east of the Sacra- 

 mento River is similar in character to the Happy Valley section, but 

 is rougher, more deeply dissected by stream courses, and has some- 

 what shallower soils. It is bounded upon the north and west by a 

 region of shallow, rocky, residual soils of the mining district of the 

 Klamath Mountains and adjacent foothills. In the southern half of 

 tliis section these wooded rolling hills gradually give way to gently 

 sloping treeless plains known locall}" as the Stillwater Plains. Here 

 is found a shallow, gravelly soil, which, in the vicinity of the narrow 

 stream valleys or minor stream courses, supports some timber. 



