60 



On the plains of the Sacramento there are some additional aqueous deposits 

 which have not made their appearance in the line of the Stockton well, but they 

 may have arisen from changes in the respective levels of water courses, such as 

 have been known to have taken place within comparatively short periods, an 

 illustration of which is to be found in two instances with respect to the bed of 

 the Sacramento River. The old bed of that stream, about nine miles south of 

 Shasta City, may be easily traced at a distance of four to eight miles from the 

 present course of the River, at a level of about three feet above medium stag< s 

 of water, and running nearly at right angles to the line on which the River now 

 runs. 



The differences caused by these additional beds, however, are very trifling. 

 Their aggregate would only amount to about 34 feet in a line of distance of 

 290 miles, and would not, therefore, affect any general result in relation to those 

 wells. 



The annexed diagram, exhibiting a longitudinal and transverse section of the 

 plains of the Sacramento and San Joaquin, will exhibit more plainly than lan 

 guage can convey, an idea of the structure of these plains so far as known at 

 the present time. 



The diagram No. 1 shows a section carried through the major axis of the 

 valley, comprising an air-line distance of 160 miles, or from the upper terrace 

 at the northern extremity of the valley, south to a point opposite to the City of 

 Sacramento in the County of Yolo. The lower clay bed is indicated at the 

 different points at which it was noticed, which will be seen, by reference to the 

 sketch, in the arroya south of Tehama; and again on the banks of the lake on 

 the western side of the Sacramento River. This is probably the same bed 

 which is found resting upon the slates some twenty-five miles north of the limits 

 represented in the sketch. By reference to the letter of Mr. Drew, respecting 

 the Stockton well, which we have exhibited in a tabular form, a close similarity 

 of the beds of the two districts will be observed, and if the waters which sink 

 beneath the surface in the more elevated districts of these plains, pass beneath 

 this bed, (and from the evidences before us, such seems to be the fact), it will 

 be necessary, as a consequence, to penetrate it in order to obtain any consider 

 able supply of water. I entertain but little doubt that the foregoing remarks 

 afford a correct idea of the true position of matters below the surface of the 

 plains, and we are warranted in these conclusions from an examination of the 

 outcropping materials on the flanks of the valley for miles in extent. The out 

 crops of the slates, sandstone and clays, on the west sides of the plains, are the 

 equivalents of those which we may expect to find beneath the surface of the 

 valley, and from the positions of the sedimentary rocks on the eastern borders, 

 we are not warranted in any other conclusion than that waters are flowing in 

 subterranean streams on the more impervious materials comprising the basis oi 

 these plains. 



From the observations which I have been able to make during the past season 

 upon these districts of the State, there have been no new facts elicited which 

 would induce any modification of the opinion entertained and expressed in my 

 former report, respecting the probable depths which it will be necessary to reach 

 in order to obtain water from artesian wells. If there exists any reason for a 

 change of those opinions, it rather tends to the increase of the depth which may 

 be required. I still feel confident that the former conclusions will be found cor 

 rect, and the figures true as to the point at which perennial springs will be 

 reached. All the evidences I can command only tend to strengthen this confi 

 dence. Still it should be recollected that it is beyond the power of man to 

 demonstrate, with absolute certainty, the depth of the stratified rocks which form 

 these plains, without actual penetration through them, and the feasibility of an 



