The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1868-09-02
THE ROCKY MOUNTAINS.


in the National Academy of sciences.
The New York Tines letter, describing the
last days session of the National Academy of
Sciences, at Northampton, Mass, contains the
following:-
A paper was read on "Some Points in the
Surface Geology of the Region West of the
Rocky Mountains" by J. d. Whitney. No
subject has been so much discussed of late
years as the ''drift." The great experience
of Professor Whitney enables him to present
this subject with acceptance. Previous dis
cussion has related to the region east of the
Rocky Mountains. In California there is no
true northern drift, no transport of material
in one general direction. The transportation
has been of a local character. In the Sierras
are numerous traces OF ancient glaciers.
The area occupied by them is very limited,
and the work performed has been in
significant. None of them were south
of SO deg. 80 min. of latitude, extending
northerly about One-third the length of the
State. The traces of the extinct glaciers have
been beautifully preserved, and nowhere can
the phenomena be- more easily stadied. The
best development of them was in the Tuol-
umne valleys. There were three general
areas of these glaciers-in Central California,
Oregon, and British Columbia. Existing gla-
ciers extend as far south as latitude So deg,
at the altitude of 5000 to Il, 900, aud are
found abundantly in British America and
Alaska, but do not occur in the United States
proper. There are no glacial markings in the
high Northern latitudes, except about the
high mountains. The great Northern drift of
the East does not extend much west of the
Mississippi, and theI efore the area occupied by
it in the United States is not more than tenth
ofits surface. The extinct glaciers of Washing.
ton Territory approach the sea level near Van
couver's Island.
The subject of the formation of lakes was
then introduced. Professor Whitney disagreed
with the views of Ramsey, who thought gla-
ciers were the chief agents of lake erosion.
Lakes were not of necessary occurrence in
glacial regions, and there were great numbers
of lakes in regions like British Columbia and
Russian Europe, where no traces of glacial
action can be found. Lakes are dependent
upon meteorological conditions. There must
be surplus of rainfall. Nevada was once
covered by wonderful network of lakes, but
they dried up for want of rain, and their
bottoms are occupied by the ''alkali flats"
The great chain of lakes in North America,
from Erie to the Arctic Ocean, occupy geolo-
gir al depression-not due to special erosion.
They are in belt of country two hundred
miles wide, and parallel to the Rocky Noun
tains.
The ground was maintained that an in
dented court is an evidence of submergence.
These indentations have been called FtordS,
from their local name in Sweden. None of
them are to be found on the western Ameri-
can coast north of Chill, but they would be
abundant in California if the surface should
sink thousand feet. None of these tiords are
found in the tropics, and they always occur
where high land borders the sea, and the in
dentations are on the west sides of the ridges.
Inasmuch as water has been so powerful an
agent of erosion in California, where the work
performed by ice has been very slight, Pro-
fessor Whitney has been led to esteem OF more
consequence the action of the former.
Professor Newberry described great lake
that once existed between the region of Lake
Superior and New York, and suggested that
some of the lakes of Oregon had been drained
by natural causes.
Mr.. Gabb thought that the lakes of Oregon
and Nevada had disappeared by simple drying
up. He remarked that he had recently ex-
amined some of the clays said to have been
produced during the drift period in South
America by Professor Agassiz, and found ma
rine fossils in them. AS these specimens
came from locality five hundred miles fur
ther up the tributaries of the Amazon than
Agassiz penetrated, he thought the views of
Agassiz incorrect.
Professor Guyot thought the facts presented
by Professor Whitney confirmed his own
theory of the glacial period, that the cold was
chiefly due to meteorological causes. When
the amount of precipitation in the winter is so
great that the heat of the summer cannot melt
the ice, then we have the conditions requisite
to produce glacial period, and the fact of the
restriction of the ice to the eastern part of the
continent was favorable to his theory. He
showed the close relations of the European and
American drift by pointing out on the map the
proximity of the two fields. They covered the
eastern part CT the latter and the western part
of the former continent. He did not think
that many of the lake basins of the world had
been excavated by glaciers.
view had been suggested by Ball, OF Ca
nada, 10 the effect that rock might have been
excavated by the falling of torrents into ice
crevasses very much like boring apparatus.
modification of this view, proposed privately
by Shaler, added the effect of heat from below.
The effects of ice would prevent the radiation
of heat from below, which might melt the
stratum of the ice, and this water, in the effort
to escape to the surface, might excavate some
of the solid lodges.
Some of the curved lake basins might have
been partly excavated by the solvent action of
water, dissolving the carbonate of lime and
carrying it off down stream. He also pointed
out the difference between the wearing out of
a perpendicular gorge and wide valley. The
former would be eXcavated by current, flow
ing directly onward without any accessions of
volume; the latter presupposes the existence of
abundant rains, washing down the upper
edges of the banks.
Trpmpndous Ola ciar Fail Naor HhamOunfy