JANUARY 18, 1901.] 
determined, and that ordinary limestone be 
compressed to see if it would yield marble, 
and that impure varieties be also used so as 
if possible to produce the silicates familiar 
as a result of metamorphism. G. K. Gil- 
bert estimated approximately the depth 
which corresponded to the pressures em- 
ployed. Roughly one vertical foot of rock 
corresponds to an increase of one pound per 
square inch, or one-half ton per 1,000 feet. 
Forty tons would therefore correspond to 
80,000 feet or about 16 miles. This should 
be reduced somewhat, as rock is slightly 
heavier than the assumption, but the dif- 
ference is slight. 
C. D. Walcott remarked the deformation 
which he had observed in the rocks of the 
ranges in California and western Nevada, 
and emphasized the different behavior of 
brittle rocks and tough rocks, illustrating 
his remarks by photographs. The brittle 
rocks break while the tough rocks flow— 
the former being often driven into the latter. 
He suggested that Dr. Adams experiment 
with cylinders of varied tenacity. 
G. K. Gilbert raised the point that rocks 
may compress slightly while they are within 
the elastic limit, 7. e., before they yield, flow 
or otherwise deform. Hesuggested the im- 
portance of determining the amount of this. 
B. K. Emerson remarked the importance 
of allowing for the phenomena of recrystal- 
lization in interpreting the results. 
Dr. Adams then thanked his colleagues 
for the suggestions, and stated his intention 
of carrying them into effect as far as pos- 
sible. 
The paper was felt by all to be one of the 
most important ever presented to the So- 
ciety, and the investigations are of such 
significance that further results will be 
eagerly looked for. 
Geomorphogeny of the Klamath Mountains: J. 
8. DittER, Washington, D. C. 
During the Neocene the Klamath moun- 
SCIENCE. 
97 
tain region of northwestern California and 
southwestern Oregon, by long-continued 
erosion, was reduced to a peneplain and 
the resulting marine sediments, rich in fos- 
sils and deposited along the ocean border, 
recorded its age. The Neocene strata 
were compressed and tilted, and with the 
Klamath peneplain and monadnocks were 
uplifted somewhat differentially several hun- 
dred feet above its former level. The invig- 
orated streams in the rather long succeed- 
ing epoch of stability cut wide valleys across 
the peneplain to the coast, where extensive 
wave-cut terraces were developed. A much 
greater differential uplift followed, and ele- 
vated the region to an altitude of 1,200 feet 
to 2,000 feet, for the Klamath peneplain near 
the coast of 7,000 feet, and near the crest 
of the range causing the streams to cut deep 
canyons before the close of the glacial period. 
Near the northern border of the Klamath 
Mountains on the coast there has been a 
recent subsidence converting the lower 
courses of the rivers to tidal inlets. : 
M. R. Campbell inquired if the peneplain 
topography could be traced all around the 
mountains. The speaker replied that, while 
is was not everywhere present, it could 
often be recognized. Mr. Campbell then 
remarked the interesting parallelism with 
the Appalachians, the similar shading of 
plains into each other and the similar in- 
terpretation of escarpments. 
As Mr. Diller had referred to great num- 
bers of small lakes upon the elevated plain 
and with local ‘fluviatile’ rather than 
‘lacustrine’ sedimentation, W. M. Davis 
suggested for the phenomena Penck’s term 
of ‘continental’ sedimentation. He com- 
pared the region to the central plateau of 
France, and urged that under compression 
surface plains would warp in a general way 
like single strata, so that in a principal as- 
. cent of a large order there would be alter- 
nate ascents and descents of a smaller order 
of magnitude. 
