Gold-Bern ing Lodes in Calif ortna. — Hcrshey, 83 
tion, all but one belong to about the same period of time, name- 
ly, the early Cretaceous. 
The Courtney Granite. — The entire range of the Cariboo, 
including the highest peaks of the Sierra Costa mountains 
(Kerr's peak, 9,345 feet A. T., Mt. Courtney, 8,500 feet A. T., 
€tc.), is one great mass or batholite of very coarse-grained, 
light gray, biotite granite, perhaps as much as five miles in 
width and ten in length. Along its borders it is overlaid by 
the schist series, but is clearly an intrusive of much later date. 
Grano-dioryte . — Scattered among the mountains east>vard 
from the Courtney granite, are small batholiths and dikes of 
a radically different variety of granite. It is finer in grain, a 
darker gray in color, and everywhere contains a large constitu- 
ent of black hornblende. It is the rock which forms the great 
granite massifs of the Sierra Nevada region, and the Montara 
granite of the San Francisco peninsula. From its composi- 
tion, being midway betw'cen that of a true granite and a dioryte 
it is commonly designated grano-dioryte. 
There are several granodioryte mountains in the Sierra 
Costa region. I am informed that the picturesque ridge, Castle 
Crag, a great object of interest along the California and Ore- 
gon railroad, is of this rock. In the lower Cofifee creek dis- 
trict, there is a belt of grano-dioryte about three miles wide and 
several times as long, trending north-south, and partly form- 
ing the prominent elevation, Billy's peak. Farther south on 
the same line are other batholiths of grano-dioryte, of which 
one constitutes the high mountain known as Granite peak. On 
the high dividing ridge between the head of Swift creek and 
the south fork of Salmon river, there is a grano-dioryte massif 
probably one-half mile in width, by one mile in length, that 
is doubly interesting because of its proximity to the non-liorn- 
blendic granite of Mt. Courtney, only three-fourths of a mile 
distant. 
Near the main grano-dioryte massifs are smaller bodies or 
true dikes some of which terminate in the mass of the bedded 
strata far below the mountain summits. However, it is char- 
acteristic of the granites of this region that they are in masses 
of relatively great width, which appear to have forced their 
way up through the strata rather than been merely injected 
into narrow fissures formed by the (jrdinary orographic dis- 
turbances, as have the other intrusives. 
