Origins ANTARCTICA, Scientific Journeys from McMurdo to the Pole
Ideas Tools Place Live Field Notes
  Peter Braddock, Tim Paulsen geology from the air  
Geologist Tim Paulsen identifies volcanic cones from the air Peter Braddock photographs them. Click to enlarge.
   

Flying Geologists

Ground truth from the air.
by Paul Doherty

December 22 , 2001

Stresses are pulling apart McMurdo station, geologic stresses, and yet there are almost no earthquakes around here. Why is that? McMurdo is located in the Mt. Terror rift zone, a place where the continental crust is being pulled apart resulting in deep valleys. Unlike other rift zones on earth, this one is covered by glaciers, what role do they play in suppressing earthquakes? With questions like these it is not surprising that a large fraction of the Antarctic population is made up of geologists.

One geology team has the office next to ours in Crary Lab. It is lead by professor Terry Wilson from Ohio State University. They are hunting for the stresses in the crust of Antarctica by looking for straight lines of volcanic cones. Lines of cones indicate where the crust has been weakened by the spreading of the rift zone. Molten magma makes its way to the surface through these weaknesses. I watched the team work day and night, marking air photos and space photos with locations of possible craters, then boarding helicopters to fly out and look closely at the cones to make sure that they really were cones and not just a trick of the light. They were geologists in search of "ground truth." Their flights revealed that some "cones" were indeed illusions. One day they invited me to join them on their search. I accepted then grabbed my ECW (extreme cold weather) gear and met them at the heliport.

  helicopter landing in a cone Mt. Morning  
View movie (4.5 MB) of helicopter flight. (Get QuickTime)
   

We donned our flight helmets, loaded the "Huey" helicopter with our equipment: cameras, air photos, notebooks and sledge hammers. When I saw the sledge hammers I knew this was going to be an interesting trip. Our pilot Chris flew across the ice of McMurdo sound, past Mt. Discovery to Mt. Morning a volcano covered with smaller cones. From the moment we spotted our first cone the geologist team sprang into high gear. Terry called out instructions to the pilot, Peter Braddock and Tim Paulsen took videos and digital still images of every cone, Jon Koenig photographed cones with a film camera.

After a half-hour Terry asked Chris to land in the flat bowl of a volcanic cone. Chris brought us down so smoothly I never felt it when we touched the ground. I just saw a shadow of a helicopter coming closer then mating with our helicopter. It reminded me of watching astronauts land on the moon, except I was starring in the role of the astronaut.

  helicopter landing in a cone Mt. Morning  
Where no one has gone before, landing in the bowl of a volcanic cone. Click to enlarge.
   

Peter took the sledge hammer and obtained a sample of bedrock, later the radioactive decay products contained in the feldspar crystals would be measured to find the "age" of the rock, the time since it solidified. (The dating technique starts by placing the rock in a nuclear reactor to transmute potassium into argon, alchemy in the service of geology.)

Jon carefully marked a rock, peter removed it with the sledge. Later, in the lab, the magnetic field trapped by the cooling lava would be measured. The magnetic field direction encodes the latitude at which the rock cooled and also gives information about the age of the rock.

  Jon Koenig marks a rock  
Jon carefully marks the orientation of a rock, later its magnetic field will be measured in the laboratory. Click to enlarge.
   

Peter noticed that I was looking at the varied array of volcanic rocks covering the ground. A few had fantastic shapes carved by the wind. He mentioned that we were probably the first people to ever walk on this ground. What an amazing experience, to walk where no one had ever been before.

During our 4 hour flight we photographed dozens of cones and landed at seven of them. From the air I thought I could detect lines of cones but since I work at the Exloratorium, "a museum of science art and human perception," I know that the human eye and brain can find lines where none exist. This is why Terry and her team will mathematically analyze all of their data to see if the alignments are real or not.

Once their observations are published,then discussed and challenged by other scientists, we may understand a bit more about the stresses in the crust underlying McMurdo sound. For sure though, I got a first hand view of modern geologists in action, using helicopters and sledge hammers, air photos and notebooks, alchemy and magnetism to explore the structure of the earth.

 

field notes
 
 
Origins Exploratorium ANTARCTICA

 

© Exploratorium