Califoniiaii Metamorphic Formations. — Hcrshey. 237 
ward toward the McCloud river, there is a deposit of the Brag- 
don slate. It contains conglomerates which on outcrop have 
a singular -vesicular character, like an amygdaloid. Now there 
are Devonian and Carboniferous limestones pretty strongly de- 
veloped in that vicinity and I explain the rounded cavities in the 
conglomerate by supposing that they represent pebbles of lime- 
stone which have been dissolved out in the process of weath- 
ering. 
The conglomerates are most abundant toward the northeast, 
and the whole formation seems to thin toward the southwest, 
implying that the shore-line and source of the sediments were 
somewhere on the northeast. In the Hay Fork country, lying 
west of the Devono-Carboniferous, there is a narrow belt of 
this formation. Here also it is closely associated with green- 
stone, as in Trinity mountain. The two are folded into each 
other and are separated by a sharp even line, with the green- 
stone always stratigraphically under. Both greenstone and 
slates are thinner than in the Trinity mountain area and the 
latter average finer sediments. 
The Bragdon slates were probably developed over the great- 
er portion of the Klamath region, but through the vicissitudes 
of elevation, folding and erosion, have been mostly destroyed. 
This is the latest of the formations included in the "Auriferous 
Slate series" of northwestern California and probably the upper 
limit of the original deposit nowhere remains. There are yet 
over 2,000 feet in thickness of it in the Trinity mountain 
country. 
The age of the Bragdon slates is as yet somewhat uncertain, 
as the formation has nowhere yielded any determinable fossils. 
Along the road between French gulch and Trinity Center, near 
Whitney's ranch, there are traces of organic remains, apparent- 
ly impressions of plants. However, no paleontological evi- 
dence is available and I can only indicate what correlations arc 
probable from the standpoint of lithology, stratigraphy and 
structure. 
In the Pitt River region, Prof. J. P. Smith has discrimin- 
ated"^' a thick series of Mesozoic sediments included in part in 
his Pitt formation and the Cedar and Bend formations, the lat- 
ter of Jurassic age. There appears to have been essentially 
''Jour. ofGeol., vol. ii. pp. 55S-<>12. 
