Geology Home Page physical geology historical geology planetary gems
Roger Weller, geology instructor
by Steve Presher
Physical Geology Spring 2015
Also see Steve's Mt. Erebus specimens
Mt. Erebus below the Antarctic Circle
Mt. Erebus is the world’s southern most active volcano, standing over 12,400
feet nearly in the center of Ross Island;
however it shares this Island with two other extinct volcano’s Mt. Byrd, and Mt. Terror.
Mt. Erebus is constantly on the move:
Mt. Erebus lies in the West Antarctic Rift System over relatively thin (20 km)
crust in what is (excellently) called the Terror Rift. This is an
intracontinental rift zone that drives extension, producing the Terror Rift
grabbed, which also hosts other nearby volcanoes on Ross Island (Mt. Terror and
Mt. Bird). The source of the magma at Erebus is referred to as the “Erebus
Plume” that is rising from asthenosphere (in the mantle) at velocities of ~6
cm/year. This is what is driving the extension in the Terror Rift grabbed.
Type: Polygenetic stratovolcano
Hazards: Lava flows, some minor explosions from Strombolian-style eruptions, tephra/ash fall.
Monitoring: Mt. Erebus Volcano Observatory (MEVO), run by New Mexico
Institute of Mining and Technology and the National Science Foundation. There
website has one of the most remarkable archives of information on a single
volcano on the internet. The volcano is also closely watched via satellite (see
below), examining the temperature of the surface of the lava lake and the SO2
flux. Erebus even once has a ro*botic explorer attempt to descend into the
crater, but it ran into some trouble. Erebus also lies close to McMurdo Station.
If you want to do some monitoring at home, there is even an Mac OS Dashboard app
for MEVO with current information of the volcano. There is also a live webcam to
watch the volcano as well
Mt. Erebus (77°32'S, 167°10'E), Ross Island, Antarctica is the world's
southernmost active volcano. Discovered in 1841 by James Ross, it is one of only
a very few volcanoes in the world with a long-lived (decades or more) lava lake.
Scientific research, sponsored by the U.S. National Science Foundation (NSF)
since began the early 1970s had included basic study of the petrology and
geophysics of the volcano, the eruptive history, activity and degassing behavior
of the lava lake, and the overall impact of the volcano on the Antarctica and
Research on Mt. Erebus has been primarily conducted by scientists in the
Department of Earth and Environmental Science and the Bureau of Geology and
Mineral Resources at the New Mexico Institute of Mining and Technology. Each
austral summer, a group of scientists and students ascend the volcano to live
and work for several weeks (early December to early January). Current research
consists of 1) continued monitoring of the SO2 flux from the lava lake, 2)
measuring the CO2 emissions from the lava lake and summit, 3) geochronology of
the summit and flank lava flows, 4) continued monitoring and interpretation of
seismic and seismoacoustic activity volcano through the use of a network of
highly-sensitive broad-band seismometers, 5) establishing a GPS base network to
monitor the short- and long-term deformation of the volcano.
Mount Erebus is located on Ross Island in the Ross Sea. Ross Island is composed
of Mt. Erebus and two other extinct major volcanic centers: Mt. Bird to the
north, Mt. Terror to the east, and Hut Point Peninsula to the south (the far
southern point of Hut Point Peninsula is the location of McMurdo
Station - the main US base in Antarctica - and Scott Base - the main New Zealand base in Antarctica. (MEVO)
One of the unique items that Mt. Erebus frequently spews forth is Erebus
Crystals. These crystals are covered by a calcite glaze which helps to hide the
beauty of these jet black crystals. The crystals vary in size, they have been
seen on the rim of the crater weighing several pounds and as small as 1.5 inches
long. . While in Antarctica in 2002 I brought a couple of smaller crystals back
with that were 1 inch wide and 1.5 inches long. Working with a fine emery cloth
the beauty of these crystals can be brought out.
In 1984 a large lava bomb was ejected from the crater. On display in the science center on McMurdo Station:
Phonolite Bomb from Mt. Erebus, found ½ km from the crater rim. This rock
fragment was part of a 2 meter diameter bomb erupted from Mt. Erebus during a
set of explosive eruptions in October-November 1984. The bomb is of phonolite
composition and contains visible an orthoclase feldspar phenocrysts. The upper
surface shown here was adjacent to the hollow interior of the bomb. The outer,
discolored part of the bomb has undergone physical and chemical weathering.
The above photo is a sample of the lava bomb on display in the science center on McMurdo Station. About the size of a soft ball it is very light and contains many feldspar crystals. It is very fragile and is constantly decaying into basalt sand.
McMurdo Station is the gateway to Antarctica; every explorer looking to cut his or her teeth on the exploration of the continent must enter through either the Ice Pier in McMurdo Station or the Air Field out on the Ross Ice Shelf, operated by the United States Air Force.
(National Geographic Map)
In 2002 National Geographic Society published this map of Antarctica. It shows
many of the discoveries that have occurred over the last one hundred years. Mt.
Erebus has been the center point of exploration in Antarctica. For 7 months it
was my pleasure to live, work and play on the continent where so few men have
been able to go.
Across Antarctica there are many scientific discoveries that I was able to enjoy
as I explored Ross Island, and the surrounding area. The plate in the center
bottom of this section of one of those discoveries, a petrified tree Only 35
miles from Mt. Erebus falling from the Mainland and out onto the Ross Ice Shelf
is the Barnes Glacier. It is one of the few Glaciers on the earth that is still
advancing. It is the only Glacier that moves across the continent on a sheet of
water, instead of advancing on solid rock. The Barnes Glacier is over 35 miles
long and stands over 125 feet above the Ice Shelf. Gazing east from Cape Evans
the Barnes Glacier stretches out across the ice and is visible for miles. While
I was standing under the leading edge of the glacier with several other
explorers we were privedgled to see the glacier calf off a berg that was the
size of a semi-truck trailer. As that bright blue berg crashed to the bottom of
the glacier landing on the Ross Ice Shelf the sound reverberated like a jack
hammer pounding on the ice. All across the ice shelf there were hundreds of
smaller chunks of ice that littered the ice shelf.
The Gentle Smell of Sulfur
if beckoning an explorer, Observation Hill looms above McMurdo Station at nearly
1,000 feet above sea level, and provides an uninterrupted view of the Ross Ice
Shelf, McMurdo Station and all points in a complete panoramic 360 degree view,
including Mt. Erebus, which itself cannot be seen from McMurdo Station. The
first man known to reach the summit of Observation Hill was Sir Aspley
Cherry-Garrard. When in 1918 he erected the cross, as a monument to Sir Robert
Scott and his party who in 1913 perished just 10 miles from Observation Hill.
The climb to the summit of OB Hill as it is
known today by the residents of McMurdo Station is an unspectacular climb.
Since the day of my arrival to Antarctica on the 21st of October of
2002 I had envisioned myself mounting the summit. However, Getting up the
courage to overcome my fear of heights would to be no small battle. Dragging
out a stepladder to change a lightbulb was no small effort. Fear of falling has
always plagued me. Fear or no fear, I was going to the top of Observation
The view across the sea ice was completely unobstructed, perfect for the assent
up Observation Hill giving a climber the feeling that one could see forever.
During the Antarctic summer the sun never sets, so fearing the loss of daylight
was no burden to Antarctic explorers so, grabbing my camera, some spare film, I
was off for my quest to the summit of Observation Hill.
On the crest of the Hill stands the cross, visible with the naked eye for
over 10 miles; an invitation to all who approach. Just as many explorers
before, today it beckoned me; Come up. Consulting my inner fears, it’s nearly a
60 degree slope to the top. A direct assent up the clearly visible path that
twisted, and turned to the summit, I felt filled with the anticipation of a 10
year old boy. Surprisingly, the same energy I had 40 years earlier as I dreamed
of climbing to the top of the bottom of the world. The first rest stop is a
turn leading to the now gone nuclear power plant, disassembled and removed from
Antarctica in 1975 when it developed a primary coolant leak, now home of McMurdo
Traversing the last snow field on Observation Hill, much of the snow already
melted away in the warmth of the Antarctic Summer, literally just fading away,
running down the hill and under the Ross Ice Shelf.
Exiting the snow field, I encountered my first hazard; the path up is very rocky. Not rocky as large boulders, just the opposite like gravel of various size and shapes.
Continuing my climb, I take time to notice the various types of rock that
littered the path up the hill. Some clearly pumice stone, some was very light
and yet others were jet-black basalt, some of it was laid down during the
eruption of Mt. Erebus in 1974 thru 1992. Often on my assent my eyes were drawn
to what I perceived were large pieces of petrified wood. Recent discoveries
here in Antarctica just north of Ross Island out on the Archipelagos, scientist
had discovered and entire petrified cedar forest. So it seemed entirely
possible; unfortunately, the specimens I found were to too large to pack down
the hill. Suddenly, I spotted something clearly out of place for Antarctica.
Antarctica was after all devoid of plant life or was it? Stooping down and
gently touching it my wildest fancies jumped to life. I had found a living
plant here in Antarctica, a patch of yellow-green lichen growing on the windward
side of Observation Hill. No larger than a fifty cent piece, yet here it was a
living plant on this frozen continent. On the grander scale of things, I could
never have seen this single solitary patch of moss. However, because I was
taking my time to explore, I was given a blessing beyond compare. Taking out my
camera, I carefully snapped a close up picture of my discovery. Exploring
Observation Hill, I had made a small scientific discovery.
My excitement once again under control, stopping to rest on a large boulder,
casting a glance back towards McMurdo Station, pausing, I leaped to my feet. I
was in awe. Looming just 12 miles away was Mt. Erebus the world’s southern most
active volcano and today she was venting a huge plume of steam and gas.
Fumbling to retrieve my camera I focused in and took the shot, and then it
happened. The gentle smell of sulfur wafted through the air.
In the plume rising into the Antarctic sky was the pungent, yet pleasant
fragrance that was the breath of Mt. Erebus. This couldn’t possibly be so? I
was over 12 miles away. Quietly thanking my Heavenly Father for this tremendous
experience I was overcome with feelings of the spirit as I heard whispered into
my mind; “With the Lord all things are possible.” In grateful appreciation,
continuing my trek to the summit.
Until now I hadn’t needed my gloves, there was no breeze, the sun shining down
gave the feeling of being at home in Seattle. Suddenly, the wind began to blow
across the summit and my hands began to ache. Like a tooth gone bad the ache in
my fingers prompted me to give in to Antarctica and put on my gloves. I’d
reached the summit. Laid out before me was a 360’ panorama of Antarctica, I was
here. Looking out across the bottom of the world, I could see everywhere for
miles upon miles. To the south, I could see the Trans-Antarctic Mountains. To
the east was Mt. Erebus; venting continuously, unfortunately, the gentle smell
of sulfur was gone. To the north was the vast Ross Ice Shelf in McMurdo Sound
and to the west laid McMurdo Station.
A top Observation Hill was the cross; nine foot tall, made of Australian Jarrah
wood, a monument to the three men on the Scott expeditionary team who perished
while returning from the South Pole in 1913. Sir Apsley Cherry-Garrard the only
member of the team to survive; returned to Ross Island in 1918 to erect this
monument. Struggling for more than two days to haul the cross to the top, Sir
Aspley Cherry-Garrard wanted something to stir the heart and spirit. Thus,
inscribed on the cross is a line from Tennyson’s Ulysses.
“TO STRIVE, TO SEEK, TO FIND AND NOT TO YEILD”
In the name of science and exploration they gave the last measure of greatness.
100 years after Scott, Shackelton and Evans arrived in Antarctica, I was there,
November 27th 2002; I overcame my own personal fears and like those
grand explorers of the last century. I came that I might do likewise. To
Strive, To Seek, To Find and Not to yield.
Mt. Erebus eruptions have deposited several layers of Basalt and Lava formations all across the Antarctic Continent. While I walked around, exploring the Ross Island and the volcanic deposits that can be found all over the island. While on several occasions I encountered many formations that were intriguing. On one occasion I discovered a stacked formation in the middle of a crushed basalt field.
Transportation down onto Antarctica is provided by the United States Air Force 149th Airborne squadron out of New York State, flying on this C-130 Hercules. Flying down to Antarctica takes over eight hours flying from Christchurch, New Zealand. Being on the Ice is how living on Antarctica is referred to. The opportunities and beauties of Antarctica can be over whelming when you consider that where you are so few have ever been. I will long remember my days on the Ice and the Gentle Smell of Sulfur that I enjoyed when I was overlooking Mt. Erebus.
National Geographic Society. Washington D.C.: Map. 2002. Dec 2001. Print
Memoirs of Steve Presher, The Gentle Smell of Sulfur Un-published
Volcano Profile: Mt. Erebus. Klemetti, Erik. July 31, 2009 web.