242 The American Geologist. Apni, 1903. 
by forcing the surrounding- strata into new positions as to be 
accurately and appreciably represented on an ordinary geolog- 
ical map. The strata which once held the position now occu- 
pied by the granite are gone. They either sank into the gran- 
ite mass and were absorbed or they were raised up vertically 
and removed by erosion. 
Contact metamorphic zones as markedly distinct from the 
regional metamorphism of the surrounding country are not 
numerous in the Klamath region. The only really prominent 
one which I have observed was called to my attention by Dr. 
H. W. Fairbanks. The largest granite batholith, extending 
from near Igo in Shasta county through the Trinity range to 
near Lewiston in Trinity county, is bounded on the northeast 
by the Bragdon series of slates, quartzytes and conglomerates. 
Adjoining the granite, the sedimentary rocks have been con- 
verted into a mica schist resembling the old schists of the pre- 
Paleozoic series. The metamorphic action is apparent to the 
unaided eye for several hundred feet distant from the granite 
and by means of a small hand microscope is yet clearly dis- 
tinguishable at the distance of several hundred yards. 
Now, nothing of the kind occurs around the granite bai-li- 
oliths where they were intruded into formations wdiich were 
already more highly metamorphosed than the Bragdon slates 
now are. When the granite rises through the hornblende schist, 
the border is characterized by breccias of angular fragments 
of schist embedded in the granite. There is not the least evi- 
dence of fusion along the contact, but every indication of vio- 
lent fracture of hard rocks. The strata removed were not 
fused in place and as the physical conditions which forced up 
these columns of melted rock preclude the probability of the 
strata having sank deep into the earth, I consider it practically 
a certainty that they were raised vertically, blown out by vol- 
canic force and have long since disappeared bv erosion. 
As the peridotyte intrusions were on a grander scale than 
those of granitic rocks, we will more surely expect in connec- 
tion with them to find evidence of the lateral compression of 
the surrounding strata. Perhaps the folding of the Mesozoic 
rocks in the Trinity Mountain area in a system which is at var- 
iance with other folds of the region may have been due to 
compression by the vast mass of melted peridotyte rising on 
