Following the acclimatization climb, on May 15th Karl Kreutz and I took a National Park Service Helicopter flight to the Mount Hunter Ice DivideAn ice divide is analogous to a watershed divide. An ice sheet divide separates opposing flow directions of ice on an ice sheet..  Andy was our pilot as he has been for several other trips around the park over the past 4 years.  Tucker, a climbing ranger for the park, acted as helicopter manager with a role of keeping us safe during the flight.  The plan was for Karl and I to finalize the exact drill site location within 5-10 feet and then locate our camp.  Our science and camping equipment weighs about 9000 pounds and in order to minimize gear hauling by hand we want the helicopter to place it precisely.  The helicopter must transport thirteen 700 pound sling loads worth of gear from base camp to the drill site over the course of a day.  So, once the helicopter dropped 9000 pounds of gear on the ice divide we certainly didn’t want to have to lug all that gear by hand and sled to a new location....even a short distance.

    Helicopter at the Mt. Hunter Ice Divide
    The helicopter had to deliver multiple loads of camping and drilling gear from Base Camp to Mount Hunter. Although the flights were not a great distance the elevation change from Base Camp to Mount Hunter is about 6,000 feet. Photo Credit: Seth Campbell

    During two field seasons in 2010 and 2011, we collected tons of data on this glacier as a potential ice core drill site.  We have spent about 60 person days at the divide before getting National Science Foundation (NSF) funding for the ice core.  The information we collected in previous years included details such as how fast and in what direction the ice is flowing, depth of ice, the appearance of the internal layering of ice, and the chemistry of the shallow snow (top 40 feet or so).  We used results from this “preliminary research” for the proposal we submitted to NSF for funding the core drilling.  On May 20th I officially spent my 30th day at the ice divide studying the finer details of this glacier.  Prior to this season we had narrowed the specific drill site down to within a 400 foot by 400 foot square region on the glacier.  Now that we are funded we want to be 100% sure that the specific spot we choose is the perfect location which means narrowing down the larger region to an area of about 100 square feet.

    Gear pile on Mount Hunter Ice Divide
    Placement of all of the gear was very important. Many of the boxes are quite heavy and exerting lots of energy moving heavy gear at high elevation would not be the best idea. Photo Credit: Karl Kreutz

    Hunkered Down on Mount Hunter
    Hunkered Down on Mount Hunter. Photo Credit: Seth Campbell

    To extract an ice core record that retains a chronological climate record we need ice with flat lying internal layering, like a stack of pancakes. Each pancake-like layer represents previous snow fall events, or years of layering at greater depths.  The top pancake is the newest snow and the bottom pancake is the oldest ice in an ice core record.  Also, generally speaking the location which has the deepest ice will provide the longest climate record.  We also want simple ice flow and ice divides represent the simplest flow because ice flows at the ice divide, theoretically, straight down (densification) and eventually away from the divide.  In a couple days of work Karl and I narrowed down the specific ice core site to a location at the exact ice divide.  The spot appears to have about 200 meters of snow and ice down to bedrock. Ice flow velocity measurements from previous years show the ice only moves about 1 meter per year to the west at this location.  We used Ground Penetrating RadarA method of estimating the distance or travel speed of an object by bouncing high frequency signals off the object and measuring the reflected signal. (GPR) to figure ice depth and to look at the internal layering at the location selected.  The internal layering does look like a stack of pancakes which is good news for us as well.  I will talk more about GPR and how it works on a later blog.  I will also do a blog that is a bit more scientific which includes results from our preliminary 2008-2011 data at the ice divide to show why this spot was chosen for ice core drilling.  SO… please stay tuned!

    Comments