98 SCIENCE. . 
President Dawson referred to the Eocene 
peneplain of British Columbia that was pro- 
tected from the sea during its formation 
by an intervening range of mountains, and 
was therefore subaérial in its character. 
He asked why the Klamath peneplain 
might not be explained by marine denuda- 
tion. Mr. Miller replied that in the Kla- 
math case Eocene strata were themselves 
trenched, and, therefore, the leveling was 
later ; and that the entire absence of marine 
sediments compelled him to infer sub-aérial 
agencies. G.O. Smith spoke of the pene- 
plain of Washington that lies between the 
Klamath mountains and British Columbia. 
It is post-Miocene, as it cuts Miocene strata, 
which have themselves been deformed, 
probably in the case of basalt by slipping 
along multitudes of joints, as suggested by 
Bailey Willis. G.K. Gilbert described the 
great Alaska peneplain,which slopes upward 
and eastward from the Alexander Archipel- 
ago to heights of 5,000 feet and more in the 
mountains. It has been vividly brought 
out by the photographs of the Survey of the 
International Boundary. He alsoremarked 
the parallelism that existed between the 
Pacific and Atlantic physiography. Pres- 
ident Dawson cited mountains of the Pa- 
cific coast 7,000 feet high that have been 
sculptured out of uplifted plains. He 
sounded a note of caution, however, lest 
the observer be misled into believing in 
peneplains which had no real existence. 
Above a certain level degradation is abnor- 
mally active and rapid, and from this alone 
mountains may reach a common and de- 
ceptive level and yet not be stumps of pene- 
plains. Mr. Gilbert, however, replied that 
his Alaska mountains were shouldered and 
therefore not open to doubt. 
Origin and Structure of the Basin Ranges: J. 
E. Spurr, Washington, D. C. 
The structure of mostofthe ranges which 
have been hitherto studied in the Great 
[N. S. Vou. XIII. No. 316. 
Basin region was first examined in detail, 
and in each case deductions were made as 
to the relative importance of erosion and of 
direct deformation, by either fault or folds, 
in determining the present topographic re- 
lief. Finally a general statement as to the 
origin of this relief is arrived at. The 
history of erosion in the region, and 
that of deformation, so far as these are 
known, were discussed separately ; and the 
history and foundation of the fault hypothe- 
sis as applied to these ranges were examined. 
The conclusion arrived at is that the ranges 
in general owe their existence to the long- 
continued erosion of rocks folded and 
faulted by many successive movements, and 
that it is only exceptional that the folds or 
faults are expressed in direct deformation 
of the present surface. 
This paper was read in abstract by C. D. 
Walcott and was illustrated by cross-sec- 
tions. It involved a great amount of detail, 
however, which it is not possible to sum- 
marize, but which will be extremely valuable 
asamatter of record. Atits conclusion the 
morning session adjourned. On reassem- 
bling the first paper read was the following : 
The Tuff Cone at Diamond Head: ©. H. 
Hircucock, Hanover, N. H. 
This cone is one of the famous ones of 
the Hawaiian Islands, and is interesting 
and exceptional in that coral, limestone 
and marine shells are copiously mingled 
with the tuffs, giving rise to a difference of 
opinion as to whether the cone is submarine 
and therefore marks a notable subsequent 
elevation of the land, or whether the or- 
ganic remains have been ejected to their 
present positions along with the tuffs. No 
discussion followed, as the Fellows seemed 
too unfamiliar with the locality to hazard 
an opinion. 
An Hypothesis to account for the Extra- Glacial, 
Abandoned Valleys of the Ohio Basin: 
Martius R. Campsetz, Washington, D. C. 
