Vor. IIT] ANDERSON—FURTHER STRATIGRAPHIC STUDY 9 
From Salt creek these Cretaceous rocks have been followed 
continuously to the Los Gatos, Warthan, Jacalitos, and Avenal 
creeks, and indeed to the Devil’s Den, on the north side of the 
Antelope valley. It is quite probable that the tawny yellow 
sandstones occurring south of the Antelope valley are of 
Cretaceous age, but as yet no proof of it is at hand. 
From the published lists of fossils occurring in the range 
it would appear that the Chico portion of the Cretaceous has 
been more often identified, though species of Aucella have 
proved the presence of the Knoxville at Mount Diablo (and 
Becker was convinced that some of the rocks at New Idria 
belong to the ‘Knoxville series”), while from the black shales 
on the Jacalitos creek species of Hoplites have been found, 
and at the Devil’s Den both Hoplites and Belemnites were col- 
lected in similar dark shales. 
It thus appears that both Knoxville and Chico strata enter 
into the composition of the range and are far more abundant 
upon the eastern flank than upon the western. The Cretaceous 
rocks always stand at a high angle, dipping away from the 
older formations and toward the valley at points of the com- 
pass varying according to their position. It is designed how- 
ever that the structure of these and the younger series of 
formations shall be reserved to be dealt with later. 
The so-called “metamorphic” rocks of the Mount Diablo 
range, occurring at intervals and in large areas, have generally 
included serpentines, trachytes, porphyries, and jaspers. The 
stratified portions are all representatives of the Franciscan 
series, while the eruptives include many of the classes usually 
found associated with them in the Coast ranges, among which 
are the products of local metainorphism of the most pro- 
nounced kinds. 
THE EoceNE Rocks 
Distribution.—The Eocene rocks of the northern portion 
of the range have already had considerable mention by various 
writers, including Stanton, Merriam, Weaver, and others. 
1U. S. Geol. Surv. 17th Ann. Rept. 1896, pp. 1009-1060. 
2Journ. Geol. v. 5, no. 8, pp, 767-775. 
3 Bull. Dept. Geol. Univ. Calif. v. 4, no. 5, pp. 101-123. 
