LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

83 3WJWEH CRETACEOUS DEPOSITS IN CALIFORNIA AND OREGON
and extended thanco southward, but with many interruptions which cannot sow be
completely followed.
The long period of time occupied by the deposition of the Chico series, And its
many intervals of interruption, and of faunal changcs, can hardly be attempted at
the present time, although it was filled with events and incidents of historical
interest equal to any mentioned in the preceding paragraphs.
CORRELATIONS
General Statement,—In the widely scattered areas of Lower Cretaceous
deposits in California and southwestern Oregon, beds that seem capable
of correlation with those in the standard column in the Sacramento Valley
have already been considered, but other areas in more remote parts of
the coast have been recorded, about which little has been known. There
are few places on the Pacific border in which the entire Lower Cretaceous
sequence, a$ exposed here, has been found. Parts of such scries
only are more widely scattered, but faunal criteria for correlation are
lacking in many coses,
Paskenta Grow p.—For tbe most port, beds referable to the Paskenta
group only have been found beyond the Emits of the Sacramento Valley.
These beds have wide distribution, but they usually contain faunas capable
of recognition as such. They have been described from many areas between
southern California and Alaska. Less frequently beds have been
described that seem comparable to the Horsetown group, as developed
in the Sacramento Valley (Shasta and Tehama counties). In southwestern
Oregon (Douglas and Curry counties), deposits referable to tbe
Shasta series are extensively developed and resemble it in lithology, and
in part in faunas, but not in stratigraphic thickness.
The "Myrtle formation" in its type district south of Roseburg, especially
near Riddle, is said to have a thickness of about 6000 feet. It
includes beds that are referable to the Paskenta group, upon which rest
other beds that may represent the Horsetown, but their thickness is not
very great. The fauna of the lower beds includes some elements not yet
known in the Shasta series of California, although neither is completely
known.
No Cretaceous deposits have been recorded from the Willamette Valley.
In the State of Washington evidences of Lower Cretaceous deposits
only have been found in scattered areas. In British Columbia, as at
Harrison Lake, Tatlayoco Lake, and on some of its islands (Vancouver,
San Juan, and Admiralty) equivalents of the Paskenta group, or parts
of it, have been found. Such beds may also occur on Queen Charlotte
Islands, but to the writer's knowledge only tbe upper portion of the Shasta
series (Horsetown) has been shown to occur there, as near Skidegate Inlet.
In Alaska, Lower Cretaceous deposits are widely distributed and, ac-