380 OSCAR. WIE STIL 
Now, on the direct line between Trinity Center and Weaver- 
ville, and thence to Junction City, there is a distinct basin or 
broad valley, three or four miles in average width, and partly 
floored by another of the Neocene River deposits. The general 
altitude of this basin is toward the north, about 3,500 feet above 
the sea, or 1,300 feet above neighboring portions of the present 
Trinity River. Examined in detail, the present floor of the 
basin is found to be quite uneven. Since the abandonment of 
this course by the Trinity River, streams which issue from 
the high mountains on the west, and formerly joined the 
main river in the basin, now continue across it and transect the 
rock ridge beyond, and have cut cafions or narrow valleys in 
the floor of the basin. A large part of the surface has been 
reduced much below the original level. So far as the channel 
deposit is concerned, only two limited portions of it are regarded 
as preserving essentially the original surface. 
On the west of the basin rise abruptly to altitudes of seven 
and eight thousand feet, the bare rugged peaks of the Sierra 
Costa Mountains. The Trinity range on the east is much lower, 
and it is difficult to fix the original line between the basin and 
these mountains. 
The old channel deposit is continuous from a point about one 
mile south of Swift Creek to the La Grange hydraulic mine on 
Oregon Mountain, between Weaverville and Junction City, a dis- 
tance of twenty miles. It lies along the western edge of the 
basin, at the foot of the high mountains. Northward from 
Weaverville, it is known through its exposure on the sides of the 
deep transverse valleys, to occupy a deep valley about one mile 
in average width, and having remarkably steep walls, a veritable 
cafion. This cafion seems to be an old valley of erosion, which 
was completely filled with alluvial gravel and sand, giving the 
Neocene deposit a great thickness, which is one of its remark- 
able features. 
We have no data for determining the actual thickness of the 
deposit, but we can fix upon a mininum in the latitude of Buck- 
eye Mountain, a few miles northeast of Weaverville. Buckeye 
