400 Adventures in Scenery 



stone, conglomerates, shale and clays, of late Tertiary and 

 Pleistocene age. 



At Lincoln is a deposit of white sand and clay (lone, late 

 Tertiary formation) and lava (andesite) . The flat plain to the 

 west comprises a deep alluvium varying from black adobe clay 

 to sand, generally very fertile. The soil along the edge of the 

 valley is commonly a reddish sandy and gravelly loam. In the 

 foothills there is little alluvium, the soils being derived from 

 the long continued distintegration of the rocks. Soils derived 

 from lava rocks generally are rich in plant food, and therefore 

 adapted to fruit-growing. Areas of andesite lava, a rock which 

 disintegrates very slowly because of its hardness, are commonly 

 covered with boulders and but little soil. 



The elevation of the valley floor in the vicinity of Wheat- 

 land is about 50 feet. To the northeast the foothills lie in paral- 

 lel ridges. Brown's Valley Ridge rises conspicuously from the 

 flat plain, with successively higher ridges beyond. 



At Marysville the Yuba and the Feather rivers come to- 

 gether, both coming from high on the Sierra Range. These 

 rivers pursue winding courses on low ridges built up by sedi- 

 ments deposited during high water. Tributary streams are 

 turned aside before reaching the main streams and become stag- 

 nant pools or sloughs, and large areas are overflowed during the 

 wet seasons. Extensive tracts are protected by levees. Minor 

 swamps and sloughs occur on both sides of Feather River. 



Marysville Biittes an Extinct Volcano 



In marked contrast to the flat plain, there rises between 

 the Feather and Sacramento rivers a circular group of moun- 

 tains, the Marysville Buttes. This group of mountains has a 

 diameter of 10 miles, the central peaks of which have an ele- 

 vation of 2,000 feet. This high isolated mountain group rises 

 with serrate and fantastic outline from the flat and monotonous 

 plain of Sacramento Valley. The Marysville Buttes constitute 

 an extinct volcano. A view from a distance shows gentle slopes 



