Story last updated at 5/28/2014 - 2:04 pm
For decades, the LeConte Survey Program has convinced a select group of Petersburg High School students to give up their lunch break, learn surveying, and practice trigonometry.
The reward? A chance to see and document LeConte, the southernmost tidewater glacier in the northern hemisphere, from a perspective no one else is permitted to. The data the students collect is scientifically valid, has been used in academic papers, and in 1993 attracted a lot of attention from scientists, said science teacher and program leader Vic Trautman.
Petersburg High School geology teacher Paul Bowen started the program in 1983. Trautman took over in the late 1990s, when Bowen retired.
For several students who participated this year, the program is a family affair. Cynthia Benitz' brother and father both participated in the program. Her father traps near the glacier, so she grew up going there.
"I just thought it would be cool to get a different angle - a different perspective of the glacier," she said.
Diane Murph's parents are surveyors, and both of her older sisters participated in the program.
"They said it was an amazing experience, and it helped them a lot," she said.
Kyle Hagerman got interested in the program while taking one of Trautman's classes. He liked the idea of doing something that had to do both with science and the LeConte Glacier, he said.
Students apply to the program, and surveyors rank their applications according to relevant criteria. Most students are in the program for two years; the first is used for training, and the second is the year they get to go to the glacier.
Every Wednesday - with a few exceptions - students head outside during lunch breaks to practice surveying. They learn how to use theodolites (instruments used for measuring angles.) They learn about the history of the program and its study of the glacier.
On the day of the survey, students land at two sites, one to the north, on a 1,000-foot ledge, and one to the south, on a 250-foot ledge. Three students and one supervisor visit each spot.
They measure as many points on the glacier as possible. Usually, Trautman said, that's around 15 to 20.
Then, the TEMSCO helicopter picks them up, and each group measures the other groups' points.
After that, they have a "math night" - an intensive evening of trigonometry, checking and double-checking their results.
In 1993, the glacier receded a half mile in only six months.
"That was significant retreating," Trautman said. "That was way before we had any of the other, quote, unquote, huge recessions of glaciers."
Trautman said University of Alaska Southeast Professor Emeritus Roman Motyka, who has helped with the program, suggested the glacier may have been sitting on an earlier terminal moraine. When it receded, it lacked support, and it calved until it found another terminal moraine - an accumulation of rocks and debris at the maximum extent of a glacier.
Tidewater glaciers function differently than valley glaciers like the Mendenhall glacier in Juneau, Trautman said. Valley glaciers tend to melt. Tidewater glaciers calve, dropping icebergs, especially when the ocean floor drops and part of the glacier begins to float.
"In the bottom of the ocean, you get a rise," Trautman said. "If it starts to go over the top of that high spot, now it's floating and it calves off."
They've only started measuring the terminus' height recently, Trautman said.
They used to record it as 250 or 270 feet above water level. Now, it's only 190 feet above water level, he said. "There seems to be a thinning trend," he said.
This year, they found the glacier's terminus has continued to remain mostly stable. The south side advanced a little - about 60 feet, Hagerman said - while the north receded about 60 feet. Overall, though, it's remained basically in the same spot.
"The face falls off continuously, but we have a map and we plot each point, so every year we get a new line," Trautman said. "We can compare this year's line to last year's line, all the way back."
Trautman said as far as he knows, the program is unique - especially for a high school.
"I'm not familiar with a high school program anyplace in the world that has spent 31 years studying the terminus of a tidewater glacier," he said. "There are professors studying various glaciers all over the world, but not too many high schoolers doing it, especially on their lunch hour."