Bragdon Foniiati'oii in N. IV. California. — Hcrshcy. 353 
apparently no more than a fourth of a mile in width. The rocks 
appear to dc less closely folded north of the Klamath river than 
farther south and in that direction the Bragdon series may be 
preserved over extensive areas. From the Trinity river south- 
ward there is a single western belt. 
The main western Bragdon-Clear Creek belt from a point 
east of Hoopa valley to the Sacramento valley, is bordered on 
the east by a belt of rocks containing limestones which have 
yielded Carboniferous types, of fossils at a number of localities, 
and is considered as probably Upper Carboniferous or perhaps 
even Permian in age.* There is little doubt of its being newer 
than the Baird shales on the McCloud river. As Mr. Diller 
places the 2^;ragdon formation at the base of the Carboniferous 
section in the Sacramento region, if he recognizes as Bragdon 
the western belts which I have so identified, he will expect the 
series to pass easterly under the Upper Carboniferous rocks. 
Mr. Diller has also shown the presence of a Devonian belt west 
of the Bragdon belt. We have then an appaient regular east- 
erly succession of pre-Devonian schists, Devonian strata, the 
Bragdon-Clear Creek series, and Upper Carboniferous rocks. 
Mr. Diller assumes apparently that the broad belt of Paleozoic 
rocks east of the fossiliferous Carboniferous belt belongs to a 
period at least not older than the Carboniferous and on this 
basis advances the suggestion that the major structure of this 
region is that of an easterly tilted fault block whereas my opin- 
ion is that the structure is geosynclinal. Between the Upper 
Carboniferous limestone belt near Hall City and the schists on 
the east there is an interval of ten miles ; and the same interval 
in the latitude of Patterson's is fifteen miles. This is occupied 
by a great thickness of extremely cherty-shistose slates whose 
lithologic characters are more like those of the Devonian than 
the Carboniferous strata of Shasta county. 
I notice some difference between this broad, very cherty belt 
and the Upper Carboniferous belt west of it. Chert occurs in 
the latter in much less abundance and the slates are harder and 
more evident to one traversing the area. The limestones in the 
known Carboniferous are heavier in development and more in- 
clined to display bedding planes. Both belts are characterized 
by great quantities of intrusive rock. Taking out those intru- 
• Amer.Jour. Set., vol. xi, May, 1903, pp. 348-350. 
