8. CALIFORNIA ACADEMY OF SCIENCES [Proc. 47TH SER. 
the character, quantity, and distribution of the various strata 
concerned in this discussion. It will readily be conceded that 
the sorting and transporting influence of ocean currents 
through channels and waterways can not be small, and that 
it is entirely adequate to explain many of the seeming irregu- 
larities, both lithological and faunal, that may appear later 
in the course of these studies. There are in some quarters 
rapid transitions in both the nature of the sediments and the 
character of the fauna as one follows the strata along their 
strike. Some important beds are known to entirely disappear 
or to change their character or appearance to such an extent 
that they can be recognized only by their stratigraphic posi- 
tion with respect to others that are better known. The later 
Miocene particularly appears to have been an epoch of rapid 
changes in these respects, but of changes that are explainable 
by sufficient attention to the details of physical geography. 
THE CRETACEOUS AND EARLIER SERIES 
It is not designed to give here any special account of the 
Cretaceous and earlier rocks of the range, although both are 
abundant about each of its older centers, as was illustrated in 
the former paper. The occurrences of Cretaceous and “meta- 
morphic” rocks have been noted by Whitney’ at Mount 
Diablo, Corral Hollow, and Panoche Pass, and have been fol- 
lowed by him as far to the south as the Panoche valley. 
Becker’ and White have published lists of Chico species oc- 
curring at New Idria, and similar beds have been identified 
upon the tributaries of the Cantua and Salt creeks. Miss H. 
C. Lillis has collected from these beds the following species, 
which were left at the University of California: 
Baculites chicoénsis Bacultes sp. 
Arca breweriana Chione sp. 
Dentalium stramineum Perissolax sp. 
Cinulia obliqua Natica sp. 
Gyrodes conradiana Margarita sp. 
1 Geol. Surv. Calif. Geol. v. 1, pp. 45, 55, etc. 
2U. S. Geol. Surv. Monog. no. 13, pp. 291-309. 
