130 Transactions of the 



tlio Lassen volcanic chain. No cretaceous rocks liave been identified 

 intermediate between Folsoni and Tejon Pass. Litholo<iically the 

 cretaceous beds are much more siliciiicd and comi)acted than the 

 tertiary. They are the shales and conj^domerates found in these 

 rc,i2;ions, while the tertiary are often loose and fi-a^dle, and scarcely 

 worthy of classification in tiie harder category, l^oth are very re<:;u- 

 larly bedded and only moderately tilted here; wliile on the opposite 

 side of the valleys of the Sacramento and San Joaquin they are both 

 tilted and altered — remarkably so in comparison with those on the 

 east side, and in proportion to their age, generally speaking. The 

 older rock formations of the Sierra foot-hills are, in the main, gran- 

 ites south of Fresno River, and slates north. I'he slate region con- 

 tains patches of granite often several miles square, and there is 

 between FoLsom and the Central Pacific Kailroad a larger patch, 

 eight or ten miles square at the least, extending from the valley to 

 near Auburn. The granite region at the south has also patches of 

 slate. Opposite Visalia, at the edge of the valley, are two isolated 

 patches ten by twelve and ten by fifteen miles. It remains only to 

 trace the boundary between the slate north of Fresno River and the 

 tertiary of the valley. Along the line, beginning at the south, are 

 the Buchanan copper mine, Indian Gulch, and Snellings, near the 

 western Mariposa County line; La Grange, Knight's Ferry, near the 

 Tuolumne line; Telegraph City, Campo Seco, Michigan l^ar, and 

 Mormon Island, near the edge of Calaveras, Amador, and El L)orado — 

 in short, a line separating these mountain counties from the valley 

 counties, or very nearly. Further north the framers of the counties 

 did not study the soil. In Placer County, Rocklin on the w<;st and 

 Auburn on the east mark the granite limits; and from there north 

 in Yuba to Oroville in Butte County, the first steep foot-hills of the 

 Sierra are of the slate formation. The iiat-bedded, unaltered forma- 

 tions of the foot-hills, described as upper tertiary, rise to very diller- 

 cnt altitudes in different places. The Oroville Cherokee mesa is, if 

 I remember aright, considerably over one thousand feet above the 

 sea at the Cherokee end. Similar isolated middle and upper tertiary 

 (miocene and pliocene) hills are found left in remnants all along the 

 base of the Sierra south of Oroville, while to the north they are 



Elastered up against the Sierra with a cretaceous base, and j^reserved 

 y a volcanic cai)i)ing covering nearly the whole country. The slates 

 and granites extend to the summit of the Sierra, the line between 

 the granites of the south and the slates of the north running slant- 

 ingly from the point mentioned on Fresno River through the heart 

 of Mariposa County toward Lake Tahoe, in a tolerably direct line." 



CLIMATE. 



From Redding in the northern end to Sumner at its southern ex- 

 tremity, as has been stated, is a distance of three hundred and fifty 

 miles. The mean annual average temi)erature of Redding is sixty- 

 four degrees and fifteen minutes. The lowest ))oint to which the ther- 

 mometer has fallen since a record has been kept was twenty-seven 

 degrees in December, eighteen hundred and seventy-six. Its annual 

 average rainfall is i'orty-eight and five one-hundrcdths inches. Sum- 

 ner, at the southern end of the valley, has an annual average tem- 

 perature of sixty-eight degrees and twenty-nine minutes, and an 

 average rainfall of four inches. The lowest point to which the ther- 



