Rootless Volcanic Cones South
of the Myrdalsjokull Ice Cap Glacier
Field photograph of a cluster of rootless volcanic cones south
of the Myrdalsjokull ice cap glacier (i.e., in the background) in
southern Iceland. Photograph taken from the highway in Iceland on
May 9, 1997. The cones are tens of meters in height and up to 100 m
in basal diameter and represent a consequence of the interaction of
erupting lava (basalt and Icelandites) with ground water.
Closeup of the rootless cones south of Myrdalsjokull
suggesting their similarity to small knobs and features
on Mars. These cones are covered with scoria and in some
cases spatter. They are spaced ~ 100 to several hundreds
of meters apart and rise up to 20 m in height. NASA
airborne remote sensing investigations of the southern
coastal plains of Iceland, in concert with scientists
from the U.S. Geological Survey and the Iceland National
Energy Authority, have sampled the relief and local
topography of such features using laser altimetry, and
this region has been imaged by the Canadian RADARSAT
satellite.
View of dust-covered ice blocks (i.e., grounded icebergs) in the
Skeidararsandur region of southern Iceland (i.e.,about
63.8 N, 17.1 W) acquired by Garvin on May 9, 1997. The
figure to the left is Dr. Helgi Torfasson of the
Iceland National Energy Authority. The ice blocks were
carried to their resting place here in the central sandur
after being detached from the terminus of the Skeidararjokull
glacier due to the jokulhlaup (catastrophic glacier outburst
flood) of November 1996 (i.e., which itself was triggered
by the October 1996 subglacial eruption in Iceland). Blocks
as large as 20 m across were carried down-sandur and deposited
due to the flood. Some of these blocks have melted, producing
ephemeral kettle "lakes", while others have been coated
with windblown tephra and somewhat insulated from rapid
melting. This view reveals the 1-3 m of local relief of the
central sandur, in the aftermath of the jokulhlaup of 11/96.
Repeat pass (differential) laser altimetry of this region
has been completed using the NASA Wallops Flight Facility
ATM scanning laser altimeter (i.e., led by Dr. William Krabill),
and results of the pre- versus post-flood sub-meter scale
topography indicate that net accretion has been observed. A
research article on this has been submitted to Nature, the text
of which will be added to this site at a later date.
All images were taken by Jim Garvin
using Kodak 200 film and using a Leica R5 SLR camera with a
50 mm lens.
Back to Geodynamics