snow
hydrology.

The science had come a long way in the century from the days when
teams of surveyors poked a hollow, calibrated aluminum tube into the
snow pack and then read depth and weighed both tube and contents to
determine moisture factors.

Those old-timers fought blizzards and avalanches from November through
March in the bleak, towering peaks of the Northwest to the weathered
crags of the Appalachians, measuring thousands of predesignated snow
courses the last week of each winter month. Upon those readings had
been based the crude, wide-margin streamflow forecasts for the coming
year.

Now, a score of refined instruments did the same job automatically at
hundreds of thousands of almost-inaccessible locations throughout the
northern hemisphere. Or at least, almost automatically. Twenty feet
above the two DivAg hydrologists and less than a hundred yards east,
on the very crest of an unnamed peak in the wilderness of Idaho's
Sawtooth Mountains, radiation snow gauge P11902-87 had quit sending
data three days ago.

The snow-profile flight over the area showed a gap in the graphed
line that flowed over the topographical map of the Sawtooths as the
survey plane flew its daily scan. The hydrotech monitoring the graph
reported the lapse to regional headquarters at Spokane and minutes
later, a communications operator punched up the alternate transmitter
for P11902-87. Nothing happened although the board showed the gauge's
cobalt-60 beta and gamma still hot. Something had gone wrong with the
tiny transducer transmitter. A man, or to be more precise, two men,
had to replace the faulty device.

The two men and the replacement gauge, trudged out again into the face
of the rising storm.

Troy and Alec pushed diagonally up the snow slope, pausing every few
minutes to take new directional readings. The needles were now at
right angles to them and reading well into the "hot" red division of
the intensity meter. They still were ten feet below the crest and a
cornice of snow hung out in a slight roof ahead of them. Both men had
closed the face hatches of their insulated helmets and tiny
circulators automatically went to work drawing off moisture and
condensation from the treated plastic.

"Wonder if that chunk is going to stay put while we go past," Alec
called, eyeing the heavy overhang. Troy paused and the two carefully
looked over the snow roof and the slope that fell away sharply to
their right.

"Looks like it a