California Tertiary Formations.—Hershey. 357 
Much of it stands readily in perpendicular bluffs, so brightly 
colored as to have suggested a name for a neighboring mining 
camp, the Rainbow District. The material is well rounded, 
regularly bedded and undoubtedly was deposited under static- 
water conditions. No fossils are present. The bright colors 
are due to its volcanic composition although no lava or tuffs 
in place appear in it. Perhaps the barrenness of life, the 
bright colors and the layers, of travertine may indicate fresh- 
water (lacustrine) rather than marine conditions. 
This non-conformity between the Escondido and Mellenia 
series is one of the best marked and most easily proved among 
the Tertiary formations of the state. The conglomerates in 
the lower series are of granitic debris, while those in the 
upper series are chiefly of lava derived by erosion from the 
lower series. Where the two adjoin there is a marked dif- 
ference in dip. In Tick canyon, the change is from 60° to 30°. 
Over the great mass of granitic conglomerate and sandstone 
in the Aguadulce and Escondido canyons, there is an altogether 
different series of conglomerates and shaly sandstones at least 
1000 feet thick resting on their upturned and planed-off edges, 
with different dip and strike. It is made up of material from 
the lavas of the lower series and is only an abnormally coarse 
portion of the Mellenia series. This latter is clearly in con- 
tact with different members of the lower series and laps past 
it at either end of the area. Before the basal conglomerate of 
the second series began to form, the first had been elevated into 
land, tilted at angles varying from 20° to 45° and profoundly 
eroded. It is certain that in places 1000 feet had been removed 
and evidence is not lacking that several times as much had 
been eroded from a large part of the basin. 
Among the lavas in the conglomerates of the Mellenia ser- 
ies are some andesytes and rhyolytes that are not known to 
have been erupted in the Soledad country and I refer their 
source to a volcanic series developed on Mohave desert north- 
ward from Antelope valley. This seems to furnish evidence 
that during the Mellenia epoch a portion of the Great Basin 
was drained by a river crossing the line of the present divide 
near Soledad pass and entering the sea by way of the Santa 
Clara basin. 
