CHAPTER XI 

 THE GREAT VALLEY 



A Structural Valley or Syncline 



The great basin of central California is one of the world's 

 outstanding valleys. Its floor embraces an area of approxi- 

 mately 16,000 square miles, about 3,000 square miles of which 

 lies less than 100 feet above sea level. Bounded on all sides by 

 mountain ranges it is both shut off from rainfall by them, and 

 watered by inflowing streams that bring back the melted snows 

 from those mountains. This great inter-mountain depression 

 or basin extends from the Tehachapi Range and the San Emig- 

 dio Mountains on the south to the vicinity of Mt. Shasta on the 

 north, 500 miles in a generally north-northwest south-southeast 

 direction, varying in width from 20 to 50 miles. On the east 

 is the great Sierra Nevada Range, rising to altitudes of more 

 than 14,000 feet. On the west lie the complicated ranges of 

 the Coast Range system. At the south the great depression 

 ends abruptly with the Tahachapi Range and the San Emigdio 

 Mountains, which ranges form a connecting link between the 

 Sierra Nevada and the Coast Ranges. At the north Mt. Shasta 

 and Lassen Peak fill the great hiatus between the Sierra Nevada 

 and Coast Ranges, these marking the southern end of the Cas- 

 cade Range. From the southward sloping lava-covered plateau 

 of far-northern California flow the Sacramento and its tribu- 

 taries. From the far south comes the San Joaquin River bring- 

 ing the waters of large tributaries which descend the western 

 slope of the great Sierra Range from the snow-capped crests of 

 the high mountains. The Sacramento flowing south and the 

 San Joaquin flowing north meet east of San Francisco Bay and 

 reach the ocean through the Golden Gate. 



This vast area, drained by two great rivers flowing in oppo- 



