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Ten Great Colorado Peak Bagging Feats - Saw this on the 14er.com site and thought it was interesting. JP

Ha replying to myself LMAO - at least my post will have one response

John et. al. - Did you check out Scott P & Chicago Transplants response on that thread? WTF -> "all (not only peaks) Colorado elevations were corrected up by 5-7 feet" No big deal? JP

johnpaul, I believe their conversation is in reference to the GEOID96 model that came out in... well... 1996. As I understand it, the National Geodetic Survey used GPS to get a better mapping of the earth's surface than previous land-based surveys were capable of. There's now a 1-sigma error of 3 cm... a whole order of magnitude better than previous surveys. This new model modified the geoid upon which altitudes are calculated (essentially, "sea level" changed). So, yes... our mountains in Colorado are all a little higher above sea level than we originally thought. :-)

John is using the standard upon which most topo maps (including the USGS) still use... which I believe is based on North American Vertical Datum of 1988 (NAVD 88). So even though we know things are a little higher than shown on maps, most people still adhere to the older measurements as the gold standard. John may have more thoughts on this.

See this thread about using old elevations.

Thanks Brian and KentonB! You guys rock

I should have searched the threads deeper. I like John's idea of waiting until the maps are reprinted because it seems like a mess to try and figure out all the nuances.

johnpaul wrote:John et. al. - Did you check out Scott P & Chicago Transplants response on that thread?

It affects all elevations, not just CO (see this article on Grand Teton). There have been many new quads created in the last few years with 'The National Map/US Topo' project, and the geoid changes do not appear to be considered/reflected. The newer quads project has been disappointing to say the least, with a lot of detail missing for newer maps (especially in WA and AZ - some of WA's long-established highest 100 fall off the list with new quads because summit contours are missing). In fact, their own article acknowledges it is an inferior product:

It is clear to most map users that the old topographic maps have higher visual quality than US Topo maps. The old maps show more features, have better text design and placement, better visual integration, and a more graceful overall appearance. A traditional hand-drawn map is a marvel of data presentation, facilitating human processing of large amounts of information quickly and accurately. US Topo maps, although superior in this regard to a typical GIS display or plot, fall short of traditional map presentation standards.

There are no spot elevations included on the newer maps available for download or the nationalmap.gov viewer.
The new maps are also being cast in WGS84 datum instead of NAD27, creating boundary issues where peaks and other features move to other quads (imagine the frustration of a quad highpointer when the boundary shifts 300' up a slope of a "liner" after previously identifying the HP and climbing it on a NAD27 boundary map) Hint: Don't take up quad or lat/lon boundary-based highpointing.

I don't think we'll be seeing geoid adjustment changes reflected on traditional quadrangle formats. With movement toward digital data formats, and higher precision data including LIDAR, I predict we'll be listing peaks from a much different methodology/perspective. It's just a matter of which technology/source is adopted as standard.