63 



would follow fast upon the steps of any system of irrigation which would successful 

 ly redeem their lands from that arid condition which for half the year gives them 

 more the character of deserts than of habitable countries. Such a process of im 

 provement would thus lead the State to new sources of revenue, not only in the 

 enhanced value of her own lands, but also in the greatly increased value and amount 

 of the improved lands of individual property taxable for governmental purposes. 



There is no part of the country more inviting in point of fertility of soil and sa 

 lubrity of climate than these valleys, and none which would be more tempting to 

 the ambition of the agriculturist, if the additional feature of a plentiful supply of 

 good water could crown the advantages which these lands possess, being in their 

 central position between the markets of the mining towns on the one hand, and 

 the cities of the seaboard on the other. 



It is to be hoped that general attention may be turned to this subject, and that it 

 will meet with such deliberation too on the part of the State Government as its im 

 portance would suggest. The higher portions of these plains, where nature has 

 supplied them with moisture, are found to be abundantly productive, both for pas 

 turage and the culture of grains, and if this moisture could by any means be secured 

 throughout the summer season in the now arid portions, there would be no obstacle 

 to the settlement through the valleys of an active and prosperous agricultural pop 

 ulation. 



TERTIARY ROCKS AND OTHER DEPOSITS OF THE SIERRA 



NEVADA. 



We shall now pass to the notice of the rocks belonging to the tertiary periods, 

 \\hich are found in the Sierra Nevada, and which extend from the middle sections 

 of these mountains to the east of the foot-hills and under the eastern borders of the 

 valleys of the Sacramento and San Joaquin. They consist of sandstone, slates, 

 conglomerates, and heavy beds of gravel drift, alternating with sands and clays of 

 the latter group, many are found in an indurated state, at times possessing a stony 

 hardness, and at others the same bed is frequently found loose and incoherent. 



On examining the rocks of this district of the State in the month of June last, 

 it was found that the tertiaries were resting upon the granites direct, and that the 

 granite had been uncovered by placer mining to a much more westerly extent than 

 had previously been assigned to their positions. These operations placed us in 

 possession of the facts, that they formed the base of the table lands near Willow 

 Springs, and within 22 miles of the City of Sacramento. The aqueous deposits 

 which are found resting upon the granites, exhibit themselves as out-liers, forming 

 the main body of the first range of plateaus above the plain, and are of the utmost 

 importance in determining the relative ages of contiguous rocks to the east. 



West of Willow Springs, in the county of Sacramento, the slates and sandstones 

 crop out near the edge of the plains ; they soon become covered with the alluvial 

 drift, and are not met with again in travelling to the east until arriving at the first 

 range of hills beyond the above mentioned locality. Between the springs and 

 these hills, the only surface rock is the granite, forming the " bed rock " of 

 this section for several miles, and lying at an average depth of about twenty-five 

 feet below the surface. At the distance of eight miles (air line) east of the 

 Springs, these rocks disappear, and are replaced by beds of indurated gravel drift, 

 having large quantities of a coarse granitic sand commingled ; this latter article 

 being heavily charged with iron, which forms the cementing medium of these beds. 

 This drift-bed has been pierced to the depth of ninety -four feet with shifts sunk for 

 mining purposes. 



