130 



Advenhires in Scenery 



site directions, is a synclinal basin hemmed in by mountain 

 ranges and having a bottle-neck outlet through the Golden 

 Gate to the sea. It is a great rock basin or structural valley, 

 and not a valley formed by the erosion of streams. The floor 

 of the basin is essentially flat, with its deeper basement floor of 

 rock formations buried under many feet of alluvial materials 

 borne by streams from the surrounding mountain ranges. Dur- 

 ing late Tertiary time the basin was filled with water which 

 connected with the sea, and thus marine sediments covered its 



Courtesy Tracy Chamber of Commerce 



FIG. 36. Cherry Orchard in San Joaquin County, in the Great Central 

 Valley of California. 



floor. Later deposits, during Quaternary and Recent time, 

 have further filled the basin. What are now the surface 

 formations, from which the present soils have been formed, are 

 the alluvial deposits that have been carried by streams and 



