Papa Bear said:
The USGS Map has a spot elevation "x 4025". This is the only "governmental or professional survey of the summit ridge " This is at the new summit, based on many GPS routes from numerous folks published here, as well as sight lines to ridges.
Both this and Scar Ridge are discussed in this thread (
here)
GPS (both consumer and professional variety) are usually considered about 3 times as accurate in location vs. elevation, with an uncertainty of 10 - 30 feet when satellite reception is good. So it's quite easy to distinguish the location of the old and new summit, even if you might doubt the elevation readings.
Since the AMC has traditionally accepted the spot elevation mark from USGS maps (see Scar Ridge debate of several years back), this is the reason folks with fancy equipment trudged up a few years back and got readings of about 30' higher (see
this thread by Dr. Dasypodidae)
So it's not just the guys taking elevation readings ("unofficial"), it's the USGS map ("official").
Thanks for posting the first link, Papa Bear, as after stirring up the Owls Head hornet's nest with my Paulin surveying altimeter in June 2005, I headed West for the summer and never read this new thread. I did read my surveying accomplice Weedhopper's (we are both geologists) final post on the thread that I started for Owls Head (your second link), but I never posted a reply, as I had nothing new to add at that time (for example, my GPS lat/long data were lousy). I did go back to Owls Head solo with my surverying altimeter in 2006, and thought that I posted those results (I seem to recall about a 5' to 10 ft vs. 15' to 25' differential between the two summits; I walked and measured twice between the two bumps over the course of about 40 minutes, hence the tighter range), but cannot seem to find any of those results posted using the VFTT search function.
So, now I am wondering if Spencer, DougPaul, and others followed up with a multi-instrument topographic survey of the ridge on Owls Head, because if they did, somehow I missed it. Although DougPaul's leveling hose filled with beer idea sounds like fun, I think that a simple hand level would be sufficient, but I keep forgetting to take one with me whenever I hike Owls Head (six or seven times now since I last carried my surveying altimeter up there!).
I agree that a small handheld GPS, even using differential post-processing, will probably not resolve the elevation difference between the bumps issue, let alone the actual elevation of the ridge on Owls Head. A Trimble navigation system might work, as suggested by Spencer, at least for the elevation difference between the bumps, if not for determining the actual elevations of the ridge. Larry Garland and his assistants used a Trimble to nail down the lat and long of trail junctions and other points of interest for the AMC topo maps, but I believe that he translated elevation data from USGS topo maps.
Since 2005, hundreds of folks have hiked to the more northerly bump on Owls Head, opening up the once difficult to follow herd paths, so using a hand level will be much easier now (one obviously uses a hand level in a series of line-of-sight measurements). Summit signs and cairns on both summits continue to come and go as hikers play cat and mouse games with the USFS rangers.
From the long thread at the first link, I do not agree with Papa Bear and DougPaul that the newer 7.5' topo maps (constructed by machines with minimal human oversight) are more accurate than the old 15' topo maps (constructed by topographers using aerial photos and transfer scopes in USGS laboratories at the Denver Federal Center). For the past 40 years of mapping that I have done on the ground across the U.S., especially in Maine and New Hampshire, I and others have found again and again that the elevation data are much more accurate on the older 15' topo maps than the newer 7.5' topo maps. We commonly map surficial geologic features that have less relief than a map's contour interval, but I am continually amazed how the old 15' maps sometimes pick up some of the larger of these features whereas the newer 7.5' maps do not. I am not including Brad Washburn's topo map of the Presidential Range with these newer 7.5' maps, of course, as Washburn's maps are the most accurate on the planet, as they should be considering the time that was spent surveying on the ground with a laser theodolite.
Thus, although all USGS topo maps are constructed from aerial photos, I feel that those from the 1960-1980s were not done nearly as carefully, when towards the end the USGS made a rushed effort to complete provisional 7.5' topo coverage across the U.S. for political reasons without hiring new mapping personnel as the old topographers retired. The USGS 7.5' maps were generally never ground-truthed in areas such as the Whites, although the USFS has re-published many of the these maps as if they were.
Although the 1967 or 1995 (USFS) editions of the South Twin 7.5' map were not provisional, like for example the 1987 Crawford Notch 7.5' map, my guess is that neither the 2023' spot elevation on the old Franconia 15' map nor the rounded off 2025' spot elevation on the South Twin 7.5' maps for Owls Head were ever surveyed, but rather "guess-timated," as they are shown in italics like most spot elevations. Compare these spot elevations with surveyed elevations that are not italicized, such as those with bench marks at two locations near the Littleton Reservoir in the northwest corner of the South Twin 7.5' map.
So, although I doubt that we will ever resolve the actual elevations of bumps on the Owls Head ridge (maybe they are not even over 4000 ft!), we should be able to confirm which bump is highest without a laser theodolite.
