California Tertiary Forimations.—Hershey. 351 
mmr IimeaminyGlitic: titi n (cee ape als Ga phehy 2.60 vis, on nial er ethiel te vie 4 feet. 
to. Green sandstone and conglomerate, ...................- 20 feet. 
PRPINEOASATIONSCONG) So cv asdina Cumcieersiesaterbiins « « Hickam 20 feet. 
12. Dark brown basalt (?) and a more acid lava with fine flow 
CUE (0) TC oe Pe PE: ae yal ees Re) er odd) “5S-feet. 
13. Dark red, very coarse tuff containing abundant Pi Ue 
OL Pereer vino efOrmationSectratcees ass v5 oy es Je ole Pee 200 feet. 
14. Dark brown, coarse-grained amygdaloidal lava, ........ 100 feet. 
Semeder iT ty. CIT OCCT SST hte aise see ads eo sce 8 6 obs xsd, 6ys 3 feet. 
RemeroAt iC. DIUE-Shay whale cect ictrar hea es epee nsse cece, A ROCES 
ere DTOWi- SAIS. .t Vier mtb Aw ies sce dvs Ke eb ee wets 4 feet. 
ie. Coarse, light: brown sandstone) c02.).05)3:. 665... : 5 feet. 
19. Series of alternating shales and Pandetanice ; nearly verti- 
cal; bright colors including red, yellow, blue and purple; 
SHALES DIT Iys UATIID ALEC @ worries sah rae s 6S alee ss hore - 150 feet. 
20. White shales impregnated with gypsum, ................ 10 feet. 
2m, Variegated shales and sandstones, ....0......4....0... 120 feet. 
22. Light blue-gray conglomerate (granitic debris largely) and 
STUBS MAIER Rta thal. Beara Se Ee oy eae tte go feet. 
23. Pink sandstone; thin and heavy bedded; dips southerly 
ORLON for UCL CES hee ee ees ieee meray Re ae hve, « 350 feet. 
Ber PeOAsse: light STAY SANAStOUG, oo. Sie 2 vs ne ch die alow ae wae = 50 feet. 
25. Dark brown, coarse-grained basic lava showing flow struc- 
Ln e ROA oe ogee cee eer are eee Rete Meee nner see Ra rcet 150 feet. 
SLO” Sars tmcs tra hc ten Bed cea urate vomaane Bese ss oha ty 4S 3864 feet. 
The lava flows were contemporary with the sediments 
and not later intrusions. In places the sandstone is red- 
dened and hardened under a lava sheet, but the sandstone over 
it is unaltered. The heavy tuff stratum (No. 13) 1s undoubt- 
edly bedded with the other sediments and it contains frag- 
ments of the lower lavas. Parts of the sheets were very ve- 
sicular, and the surface of the volcanic area abounds in chal- 
cedony which has weathered out of the amygdules. 
The lava is local in its heavy development. Through its 
resistant properties it gives rise to a range of rugged black 
mountains. Just east of Tick canyon there seems to have been 
a center of eruption, marked by an unusually prominent group 
of peaks. The sandstone layers among the lava sheets were 
somewhat broken up, apparently by subsequently erupted lava. 
The different sheets, about five in number, thin rapidly to east 
and west and at the distance of one mile several have wedged 
out entirely. At one place the lower sheet is in contact with 
the gneiss, but I have a suspicion that the contact between the 
