59 



surface, and which are equivalent, the one with the other. The following table 

 will exhibit the relations of these beds, though nearly two hundred miles apart. 



With the exception of the upper gravel beds, which occur in the higher terraces 

 of the northern part of the Sacramento Valley, the beds below the surface on the 

 San Joaquin will be found to correspond in their general features very closely with 

 the deposits which are traceable above the surface, from the City of Sacramento to 

 the south banks of the Pitt River. 



The figures give the maximum depths at which each of the deposits were met 

 with in both sections of the State, and the diagrams exhibiting the transverse and 

 longitudinal sections of the plains, show the relative positions of the respective beds 

 as far as known at the present time. 



TABLE SHOWING THE POSITION OF THE EARTHY DEPOSITS OF THE PLAINS OF THE 

 SAN JOAQUIN AND SACRAMENTO ABOVE AND BELOW THE SURFACE. 



Beds of the San Joaquin below the surface. 



Light dark red clays and sand, 40 



Grey sand and clay, - - - - - 170 



Blue clay, gravel and sand above, -. - "237 



Light grey sand, - - - 265 



Fine clear gravel, - - - 346 



Blue clay, - - 400 



Total, 400 



eds of the Savramento above the surface. 



Alluvium, lava, light red clays, 52 



Upper gravel beds, - 66 



Light sandy clay, - 160 



Sand, gravel, blue clay below, - - 225 



Light greyish sands, - 276 



Fine gravel, sand and blue clay, - 338 



Blue clay, - - 358 



Total, 358 



The above table exhibits a strong coincidence in the coverings of the valleys 

 at nearly two extremes of the State, and the observations leading to the above 

 results being entirely unconnected with each other, there certainly exists good 

 reason for the belief that the earthy coverings above the stratified rocks will 

 maintain a great degree of uniformity over the entire basin. 



The depth of the Stockton well is not so great as the boring at Los Angeles, 

 the latter being 465 feet below the surface point of starting, 432 feet of which 

 has been carried through the blue clay entirely. This clay has increased in den 

 sity and hardness as they descend, and contains embedded boulders of other 

 rocks. 



For the above information I am indebted to Messrs. Butts & Wheeler, of Los 

 Angeles, in a letter describing the progress of the well after I left that part of 

 the State, during the month of October. The Santa Clara wells produce their 

 supply of water from a bed of fiue gray sand, which lies immediately beneath 

 the heavy clay bed, which varies from 75 feet to about 100 feet in thickness. 



