l6 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



it consists of the Knoxville with the overlying Horsetown 

 and Chico strata; while on the North Fork the base of 

 the Horsetown rests directly upon the older metamorphic 

 and granitic rocks. 



Along the eastern side of the Sacramento Valley, in the 

 foot-hills of the Sierra Nevada, only the upper portion of 

 the series has been found, resting upon the metamorphic 

 rocks of the "Gold Belt." Here the horizon, which 

 perhaps should be considered as most typical Chico, is to 

 be seen, though Gabb evidently included under that name 

 more than is there represented. Diller states that the beds 

 along the eastern side of the valley are much less disturbed 

 than those on the west, being often nearly horizontal. The 

 entire Cretaceous series, as has been shown by former 

 writers, forms in the northern half of the Great Valley a 

 geosyncline, which in its central portion passes below and 

 is hidden by the accumulation of Tertiary and later strata, 

 but which reaches the surface along both borders of the 

 valley in the foot-hills of the Coast Ranges and Sierra 

 Nevada. 



In the papers already cited, Mr. Diller has shown that 

 the Cretaceous series of the West Coast, as is illustrated by 

 the deposits of the Sacramento Valley, was laid down 

 under conditions of prolonged subsidence. A continuous 

 though unequal settling of the sea-bottom from first to last 

 is apparently demonstrated not only by the continuous and 

 unbroken order of the series above described, all of which 

 seems to indicate shallow water, but also by the successive 

 overlapping and transgression outward of the younger por- 

 tions of the series upon the border of older rocks that 

 circumscribed the Cretaceous waters at each -epoch. The 

 differential action of this movement in the coast regions 

 cannot be better stated than in Mr. Diller's words (Diller and 

 Stanton, 1894, p. 456). He says : "The large extent of this 

 subsidence, from Alaska on the north to Lower California 

 on the south, makes it an epeirogenic movement. There is 

 evidence, however, that the movement, although epeirogenic, 



