Denali Summit Survey

By Britta Schroeder (last updated April, 2016)

NPS Photo

The highest peak in North America has gone by many names and many elevations over the centuries. Pre-contact, each Native Alaskan language area called the mountain by a different name. These names included the Koyukon Athabascan name for the mountain, Denali.

Similarly, different heights have been estimated or measured since the late 1800’s. The most widely accepted height of Denali's south summit is often cited as 20,320 feet and was derived from a 1953 photogrammetric survey. More recently, in 2013, remote sensing data acquired over the area of the peak suggested a height of 20,237 feet. While this height of 20,237 feet was accepted as the new official height by the State of Alaska, the National Geodetic Survey did not recognize this new height. To address the discrepancy between these two heights, during the summer of 2015 a GPS survey was conducted on the summit of Denali’s South Peak to determine a more accurate elevation for the mountain.

Probing Denali’s ice cap for the GPS antenna location.

CompassData Photo / Blaine Horner

In June 2015, a survey expedition used modern GPS equipment and methods, along with a better geoid model, to determine a new elevation of 20,310 feet. The team probed the depth of the ice cap on the peak (Figure 2) to determine the location of the rock beneath the ice cap. They estimated the depth at 13.6 feet but could not definitively identify the rock summit. So, the new elevation of the mountain was measured to the top of the ice cap. Two antennas were set up, to serve as accuracy checks and as a back-up in case of failure (Figure 3). Fourteen hours of satellite data were logged during the survey, which increased the accuracy of the data. Three separate entities (the University of Alaska Fairbanks, the National Geodetic Survey, and CompassData) analyzed the GPS data and each arrived at the same height, with negligible differences in the results. 

This new height of 20,310 feet, which is now accepted by the U.S. Geological Survey and the National Geodetic Survey, usurped the previous height of the mountain that reigned for over 60 years. The more accurate height was announced during the same week the federal government announced the official restoration of a Native Alaskan name to the mountain: Denali.

Two GPS antennas measure the height of Denali’s South Peak.

CompassData Photo / Blaine Horner