Klamath Mountains, California. — Hcrshey. 233 
The Paleozoic series is estimated to be not less than 5000 
feet thick and seems to represent continuous deposition in a 
broad sea basin. The Mesozoic series is divided sharply into 
two formations, of which the lower was composed of volcanic 
materials such as andesite and rhyolite lavas and tuffs, intrud- 
ed by dikes of diorite, diabase and rhyolite porphyry, all now 
altered to rocks abounding in sericite, chlorite and epidote. 
This complex of volcanic materials, the Clear Creek series, 
is overlaid unconformably by several thousand feet in thick- 
ness of alternating black slates and blue quattzites, with con- 
glomerates locally developed, the whole taken together as the 
Bragdon formation, which is supposed to be of about the same 
age as the Mariposa formation in the Sierra Nevada region 
and hence late Jurassic. The total thickness of the stratified 
formations so far as known is about 12,000 feet, but probably 
a more thorough study of the region will show the real thick- 
ness to be several times as great. 
East of the Sacramento river, Diller, Smith and others 
have shown that there is there developed a Mesozoic series of 
slates, limestone and sandstones of late Triassic and early and 
middle Jurassic age, which seems to be totally unrepresented 
west of the Sacramento river, except in a few small remnants 
near Redding, its place in Trinity county being occupied by 
an erosion interval. This region east of the Sacramento river 
and a narrow strip west of that stream have lately been 
thoroughly investigated by Diller in mapping the Redding 
Quadrangle of the United States Geologic Atlas, and its geol- 
ogy is hardly within the province of this paper. 
The distribution and relations of the stratified formations 
of the Klamath region isouth of the Klamath river, are now 
sufficiently well known to make the following history of their 
deposition reasonably certain : The original sediments of the 
Abrams mica schist were laid down on the sea bottom with 
comparative uniformity ' of character and thickness over the 
entire area. Upon them were deposited the supposed volcanic 
ashes which have been metamorphosed into the Salmon horn- 
blende schist. Apparently this also extended beyond the ter- 
ritory now under discussion. Then these two formations were 
metamorphosed, uplifted and eroded. The denudation in places 
cut away the hornblende schist and exposed the mica schist. 
