132 Transactions of the 



materially differ from that in the Sacramento Valley. This fact is 

 prohably to be ascribed to the ]n'evailing soutiiwest return trade 

 wind which blows over the State from the ocean for more than three 

 hundred days in the year. Passing tlie summits of the Coast Range 

 but small portions descend into the valley; the remainder reach 

 the sides of the Sierra at about the level of the summits they have 

 passed. 



ARBOREAL VEGETATION. 



At the northern end of the valley, at an elevation of five hundred 

 feet above the sea, of the California oaks are found Quercus lobata, 

 Sononirnsis, Clirijsolopis, Wislczcnli ; of pines, only the nut or Digger 

 pine {Finus Sahlintana) ; the buckeye {yEscnlus Californica), and chem- 

 isal {Adenostoma fasicidata). This is the characteristic arboreal vege- 

 tation throughout all these three hundred and fifty miles. Its 

 presence everywhere shows increased rainfall over the valley and 

 similiarity of temperature to that of the valley. Our pasture oak 

 {QucrcHS lobata) is found at lower elevations, in the valley, but always 

 on moist land or near river courses, proving that it demands, in 

 addition to temi)erature, the increased moisture. In the southern 

 end of the valley this vegetation prevails at higher elevations, 

 because it there finds the proper temperature and moisture. Whore- 

 ever on the foot-hills any of the trees named constitute the predom- 

 inant arboreal vegetation, it is evidence that the temperature is the 

 same as that of the valley, and that plants that can be successfully 

 grown in the valley can be grown to as high an elevation on the hills 

 as these trees abound. If one tree were to be taken as the evidence of 

 this uniformity of temperature it would be Sabin's (the nut, or Dig- 

 ger) pine. It is never seen in the valley or on the hills below an 

 elevation of about four hundred feet. It is not found at a higher 

 elevation than that in which the temperature is the same as that of 

 the valley. It is never found in groves, but singly among other 

 trees, yet it prevails throughout these three hundretl and fifty miles 

 of foot-hills. While the vegetation is more dense on the hills at the 

 northern end of the valley, due to increased precipitation, there are 

 also local differences — where there is similarity of soil — due to expos- 

 ure. Throughout all the lower hills the greatest number of trees 

 is found on gently sloping eastern, northeastern, and northern hill- 

 sides, which necessarily are more moist and cool. The southern 

 asi)ects contain less trees because exposed to the direct rays of the sun 

 and to the full force of the prevailing winds. 



AREA OF FOOT-HILL REGION. 



On the line of the Central Pacific Railroad the foot-hills commence 

 at Roseville, which has an elevation of one hundred and si.Kty-three 

 feet. From this point to Colfax — elevation, two thousand four hun- 

 dred and twenty-one feet — in a direct line is a distance of thirty-two 

 miles. To allow for all possible errors it would be safe to estimate 

 that the widtli of the foot-hills, where the valley temi)crature i)revails, 

 is twenty miles. This region, therefore, embraces a tract of country 

 from Redding to Sumner, three hundred and fifty miles long and 

 twenty miles wide, or four million tour hundred and eighty thous- 

 and acres. The principal towns in this part of the State are Oroville, 

 Nevada, Grass Valley, Colfax, Auburn, New Castle, Georgetown, 



