Evening star., 1952-05-12
Recession of Glaciers
Slows After as Years
Ice Rivers Hurd to Check
Because of Their Behavior
By Thomos R. Henry

The great recession of glaciers within
the continental United States which hal
continued for about IS years appar.
emily is slowing down. J.
It is possible that the advances and
recessions Of glaciers-perhaps the world
over-take place in great waves, one Of
which has just passed its apex. The
slowing down Of the recession was re-
ported to the American Geophysical
Union here this week by DR.. w. o. Field
Of the American Geographical Society,
chairman Of the unions Committee on
Glaciers.
The two best-known glaciers within
the continental limits are the Grinnell
glacier in Glacier National Park and
the Musquah glacier in Mount Rainier
National Park. It is possible to watch
these ice rivers moving almost from
hour to hour.
Decline In Recession.
From 1887 to 1s45. Dr. Field said. re-
ports to the committee show that the
Grinnel receded at q rate of 1913 feet q
year. From 1945 this speed of recession
has declined to an average Of IA feet
year and In the last couple of years any
recession at all is questionable.
Almost from the start of the cen.
tury the Musquai glacier was retreat
ing at q rate of 40 feet q year, on the
average. Then this speeded up to u
feet year. Now 1t also has slowed down.
In 1914 the surface Of this glacier was
observed to be rising. In one year it
rose 40 feet and the rate of flow was
seen to be increasing. This may have
marked the elimination of the recession
wave. DR.. Field believes. Similarly, re-
cesSion Of a, half-dozen glaciers under
close observation seems to have stopped.
The actual status of a glacier always
Is difficult to determine because it sell
dom behaves in the same way from one
season to another. In one year 1t may
retreat and in the next year q slight
ice river actually Is advancing or re-
treating depends on the average over q
course Of years.
Two Of the most far-reaching and in
tensive studies ever made of glaciers
now are underway under the auspices Of
the Office Of Naval Research. DR.. Field
said. The first of these is the longtime
study Of the Juneau iceflelds near Ju-
neau, Alaska. This involves many angles,
including such widely separated ones as
physics and botany. An intensive study
Of ancient pollen obtained from peat
sections on the southwest flank Of the
ice fields has just been completed. It
has shown, DR.. Calvin j. Huesser of the
American Geographical Society reported
to the Geophysical Union, very extern
sive and relatively recent climatic
changes In that part Of Alaska.
Warm Climate Previously.
'"The ice field" he said, els today an
area of approximately 700 square miles
and its present size is attributed to the
change IN climate which occurred a
little over 1000 years ago. Prior to
this date warm. dry climate prevailed
from 5000 to 1000 years in the past.
The earliest pollen-bearing sediments
are estimated at 5000 years old and dis
close considerable instability in the re-
gion between that date and 5000 years.
Amelloration Of climate and increased
stability took place between 5000 and
5000 years ago. Present pollen profiles
corroborate the present day warming
and recession of the glaciers" ~
Another major glacier study now un.
der way is that Of the California Insti-
tute OF Technology in the ice fields Of
the st. Elias mountains in Alaska. This
also is supported by the Office of Naval
Research.
The California scientists have set up
camp in the middle of the largest ice
sheet, at an altitude of about $4,000
feet. A pipe has been sunk to a depth
OF nearly 10000 feet in the ice in an
effort to detect any internal movement
not apparent on the surface.