Grandfather Mountain President Crae Morton announced this week that, based on a recent survey by Doug Suttles of Suttles Surveying in Marion, NC, Grandfather Mountain will list the elevation of its summit as 5,946 feet.
This number is 18 feet lower that the elevation of 5,964 feet that Grandfather Mountain has been using in its promotional materials since opening as a scenic travel attraction in 1952. The higher number originally came from North Carolina Geologic and Economic Survey Bulletin No. 27 entitled “Altitudes in North Carolina” published in 1917.
There has been a plaque on the steps to the Swinging Bridge that marked a spot that was one mile in elevation since the attraction opened in 1952. But in the summer of 2007 surveyors found that when they stood on that spot, their GPS equipment did not register 5,280 feet. Morton then decided to have experts bring in all the proper tools necessary to verify the height of Grandfather Mountain.
Suttles Surveying utilized global positioning systems and dual frequency receivers to collect data at 10 second intervals for five hours on a total of three of Grandfather’s peaks. The data he collected were sent to the National Geodetic Survey Online Positioning User Service (OPUS) where they were converted to Latitude, Longitude and Elevation. OPUS uses data from a network of Continous Operating Reference Stations (CORS) that were established as part of the National Height Modernization Program in NC. After some final “least squares adjustments,” Suttles arrived at the 2008 elevation figures that Grandfather Mountain is now using.
“From all we can learn there is no official agency that needs to authorize use of these findings,” said Morton, “so we have decided to use the elevation of 5,946 feet in all of our future publications because it reflects the best data available to us at this time.”
Work performed by Professional Land Surveyors in North Carolina must meet the minimum standards as established by the North Carolina Engineering and Surveying Laws. Gary Thompson of the North Carolina Geodetic Survey said his office reviewed Suttles OPUS output and that all of the OPUS indicators looked good.
Steve Strader, Geospatial Liaison to North Carolina for the US Geological Survey, said that Suttles’ numbers have been put into a USGS database called the Geographic Names Information System.
“The data was gathered by a licensed public land surveyor,” said Strader, “making it the best information that we have for that peak.”
Concurrently with the change in the listed elevations, Grandfather Mountain will no longer be reported as the highest peak in the Blue Ridge.
“Grandfather Mountain’s status as the ‘highest peak in the Blue Ridge’ is correct by certain definitions of what really is the ‘Blue Ridge,’” explains Morton. “However, geologically-speaking, Mount Mitchell (elevation 6,684 feet) is also part of the Blue Ridge chain, even though many think of it as exclusively part of the Black Mountain range. Regardless of all the names and definitions, our geologist friends tell us Mount Mitchell is the highest in the Blue Ridge, and we’ll defer to the professionals.”
Interestingly, the recent surveys have determined that the Swinging Bridge is exactly one mile above sea level. Historically it was thought that the Bridge was about 20 feet higher than a mile in elevation, but the data shows the north end of the Swinging Bridge (near the parking area) to be 5,282 feet in elevation and the far end to be 5,278 feet in elevation.
“That means that there is a spot in the middle of the bridge that is precisely five-thousand two-hundred and eighty feet above sea level,” said Morton.