6 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1910. 



The Red Bluff area covers a section of the valley from its northern 

 end, near Rod Bluff, southward to the Colusa area, a distance of 

 about 27^ miles, a prolonoation of tlie eastern and western boundaries 

 of that area forming similar boundaries for the Red Bluff area. The 

 area is covered bj^ the Vina and Tehama quadranfjles of the United 

 States Geological Survey,, these sheets being used as base maps. An 

 exception is made of that part of the Vina Quadrangle previously 

 covered in the Colusa area and such parts of the Tehama Quadrangle 

 as have but comparatively little agricultural value. • 



The area consists of approximately 326 square miles, or 208,640 

 acres, all in Tehama County with the. exception of some 10 square 

 miles in the southeastern corner Wn\g in Butte County. It would l)e 

 rectangular in shape were it not that the lower Piedmont Plain of 

 the Lassen Peak district, of no agricultural importance, borders the 

 Sacramento Ri\er rather closely in the northeastern part of the area. 

 The boundary of the survey is here so drawn as to include but little 

 of this plain, the dissected front of which forms the boundary of the 

 valley. 



The Sacramento River enters the area near the northwest comer 

 and pursues a general course to the southeast corner, dividing the 

 area so that somewhat the greater part lies upon the west side of 

 the river. 



At the point where the river leaves Iron Canyon and enters the 

 area an irregular flood plain, known as the '' Sacramento Bottoms," 

 begins. This varies in width from 1 mile to several miles. Through 

 these bottoms the river meanders in an ever changing course. Dur- 

 ing excessive Hood periotls great areas of these bottom lands are 

 submerged and active erosion follows through the overflow waters 

 seeking lower levels by shorter channels than the tortuous river course. 

 The main channel throughout the area occupies the lowest part of 

 this alluvial bottom and in the main has sufficient carrying capacity 

 promptly to relieve flooded sections. The condition does not exist 

 in the Red Bkiff area as farther south whereb}' a belt of elevated 

 alluvial material has been built up along its banks, forming basins 

 to restrain escaped flood waters after the river has fallen. 



Few attempts are made to levee the river and keep it within its 

 banks, and during flood seasons the water does considerable damage 

 by restricting the area suitable for agriculture. 



This flood plain throughout is marked by meandering overflow 

 channels sometimes giving sections a much eroded surface. Such 

 areas are abandoned to a tangled growth of wild grape, cottonwood, 

 sycamore, willow, etc. The bottom lands were originally heavily 

 wooded with the trees mentioned and when the agricultural develop- 

 ment of the area started much labor and expense were necessary to 

 clear it. It is now as extensively cleared as flood conditions warrant, 



