252 The American Geologist. -^p'''^' 1904. 
traversed in various directions by narrow shear zones in which 
the shales have been crushed into a black, glistening schistose 
slate. This is its appearance in most of the mines of the area 
because along the veins there has usually been faulting and 
shearing. But in traveling over the area one is usually im- 
pressed with the fact that dynamical metamorphism has been 
generally absent. 
The conglomerates are the most characteristic portion of 
the series. They occur throughout this eastern area, but are 
most strongly developed toward the northeast, in the vicinity 
of the Sacramento river. Along the Trinity Mountain belt, 
there are areas acres in extent which are bestrewn with angular 
fragments of all sizes up to three feet in diameter, of gray con-' 
glomerate in which the pebbles are mostly between one-fourth 
inch and one inch in diameter, and consist almost ex- 
clusively of variously colored cherts, including red and 
black, all of which can be referred for an origin to the 
Paleozoic rocks. Some of the fragments, lying in the beds of 
creeks, attract attention by their speckled appearance. The 
lithification has continued to the extent that the rock fractures 
through the pebbles rather than around their borders. The 
thickness of the layers must be in places from ten to fifty feet. 
There seem to be locally heavier developments as near Dead- 
wood, French Gulch and along the new wagon road intended 
to connect Trinity Center with Delta. One may cross Trinity 
mountain along other lines without much noticing conglomer- 
ate fragments. In Trinity valley, the conglomerates do not ap- 
pear at the base of the series, but are scattered through the 
formation to a considerable height above the base. Near the 
Sacramento river, I believe Mr. Diller has found some of this 
conglomerate at the base of the series, resting on the Paleozoic 
rocks. 
There is nothing in the stratification in Trinity mountain 
and westward to indicate beach conditions, but in the thicken- 
ing and coarsening of the conglomerates in the direction of the 
Sacramento river, we probably have evidence of an approach 
to the eastern shore-line of the Bragdon body of water. The 
conglomerates in that region are supplied with limestone peb- 
bles which weather out near the surface and give the rock a 
vesicular appearance. This may be seen from the train in ap- 
