Jökull - 01.01.2004, Page 90

Richard S. Williams, Jr. and Magnús Már Magnússon
Figure 1. View of Icelandic Coast Guard helicopter (TF-GNA) landing on Tungnárjökull to deliver a
replacement transmission for the Bombardier. This is one of the last photographs taken of TF-GNA before
it was destroyed in an aviation accident later in 1974. Soffía Vernharðsdóttir is visible in the left foreground,
Heinrich Wettstein in the right foreground. Photograph by Richard S. Williams, Jr., U.S. Geological Survey. -
melted and dripped all night. Everyone but Magnús
Már Magnússon slept in the hut (13 people); Magnús
Már slept in the Bombardier. We devoted the remaind-
er of the morning and early afternoon to removing
the rest of the snow-and-ice encrustation from the hut
(starting with the roof) and constructing privies with
snow-block walls to shield users from the wind.
We departed at 1430 hr for the surface of the
snow- and ice-covered, subglacier lake in the Grím-
svötn caldera. There was independent skiing or tow-
ing by the Bombardier (Figure 2), as we traversed the
caldera from east to west; we stopped every 0.5 km to
obtain elevation measurements of the snow-covered
lake surface. We stayed for a long time at Naggur,
a palagonitic ice-cored hill in the western part of the
caldera. Carl Eiríksson, our navigator, went to loca-
te the benchmark at Stóri Mósi to make reference-
elevation measurements, while the rest of our exped-
ition headed back to the east. There we dug a snow
pit in the center of the snow- and ice-covered lake to
determine the annual accumulation of snow, firn, and
ice. Snow-pit digging began at 2045 hr and finished
at 0200 (29 May). We encountered a snowmelt layer
of ice, which indicated the melt-layer horizon mark-
ing the 1973 summer surface, at 6.07 m. This depth
indicated about 1.5 m greater annual accumulation th-
an usual.
29 May:
The air temperature fell to -12◦C overnight. The
trip to Kverkfjöll began at 1430 hr. The Bombardier
towed skiers all the way, and we arrived at the ea-
stern side of the mountain summit at 1800 hr. After
reaching the eastern summit, where the temperature
was -7◦C, we drove over to the western side of Kverk-
fjöll and hiked to the ridge crest and observed steam
issuing from the west-facing slope. We descended
90 JÖKULL No. 54, 2004