250 The American Geologist. ^p"1' "<^*- 
portion of the main western Bragdon area than the eastern or 
type area. 
Mr. F. M. Anderson, in conversation with me, suggested 
that the age of the Bragdon formation might be Devonian be- 
cause of its occurring west of a Carboniferous belt in a region 
in which there seems to be a general eastward succession of the 
strata so far as age is concerned, but subsequently he seems to 
have hit upon the Triassic as the period which best fitted his 
observations of the slates of Trinity mountain.* 
I have found no fossils in the Bragdon formation except 
imperfect plant impressions near Whitney's in the valley of 
Clear creek, near Van Ness mine on the opposite side of the 
Trinity range and at various places along the trails between 
Trinity Center and Slatonis and Delta. They invariably occur 
in a peculiar sandy shale. Mr. Diller has since found plant re- 
mains in similar strata near Slatonis and has taken consider- 
able pains to have them identified, submitting them to Fon- 
taine, Ward, White and Knowlton, but while the most definite 
opinion expressed seems to support a Jurassic age, the fossils 
are too imperfect to be of any weight whatever in deciding 
whether the Bragdon formation is Carboniferous, Triassic or 
Jurassic in age, so that unless better fossil material be discov- 
ered in the future, we will be compelled to fall back on strati- 
graphic evidence in fixing the probable age of the formation. 
Mr. Diller has recently discussedt at some length the Brag- 
don formation, giving all the available paleobotanical evidence 
and provisionally placing it at the base of the Carboniferous sec- 
tion of the Sacramento River region. This conclusion he bases 
upon his study of its areal distribution and stratigraphic rela- 
tions, a method of procedure very similar to that by which I 
have concluded that it is probably late Jurassic in age. Mr. 
Diller states that I have referred it to the Jurassic largely on 
lithologic evidence which was true in the earlier stages of my 
study of it, but in the past two years I have gathered a large 
amount of additional data which lead me, more strongly now 
than ever, to maintain its late Jurassic age on broad structural 
or stratigraphic grounds in addition to the lithologic evidence 
and the purpose of this paper is to place this material in detail 
* California State Mining Burean. Copper Resources of California — Geol- 
ogical Map of the western part of Shasta County. 
t "Klamath Mountain Section of California," /Imer. Jour. Sc;.. vol. xv, 
Mav, 1903. 
