Spirit Mountain Peak Markers

According to the data sheet it was set in 1925 and the two reference marks weren't set until 1934. Data sheet makes no mention of any stampings or markings on the main disk. As shown on the perimeter of the disk it was a triangulation station, it's primary azimuth mark was another point named Cresent which was approx 43.1 km away.

Thanks for the info, Stephen. I Googled Crescent Peak, and it looks about 43 km to the west of Spirit. Now that's a backsight!

Dave

Data sheet also gives an NAVD 88 ortho height to the nearest foot (5,642'), but once you wade through all of the info you discover that it was determined by running the NGVD 29 elevation through VERTCON. The NGVD 29 elevation was determined using vertical angle observations.

> The two "pointer" markers looked old and tarnished. The peak marker looked almost new. It didn't have anything stamped on it, so I assume this is a redo.

It seems pretty unusual to see a station disk without its name stamped into it. However, since mark setting conditions varied so much, it's possible to imagine a situation in which the name didn't get stamped and a return visit just to stamp it was deemed impractical.

The difference in coloration between the station disk and the RM disks is interesting, but might be attributable to differences in the alloys used. The fact that the station mark bears the USC&GS rather than the NGS imprints tends to support the 1925 date, though the old disks were reportedly still in use in the early 1970s.

> Is this going to be just an elevation marker, or will it be a HARN point?

Probably neither at this point. GPS has rendered most of the triangulation stations irrelevant.

> Before GPS, how did they get an elevation on a mountain peak?

As Stephen mentioned, VABM was a common approach. However, some of them were leveled. As an extreme example, there's a First Order level run up to the top of Mount Whitney in California, a peak that's over 14,000 feet and about 10,000 feet above the surrounding flatlands. It's a very demanding hike even when you're not carrying survey equipment, and when I went up there I marveled at the thought of a survey crew running high-precision levels to the top and back.

> .... As an extreme example, there's a First Order level run up to the top of Mount Whitney in California, a peak that's over 14,000 feet and about 10,000 feet above the surrounding flatlands. It's a very demanding hike even when you're not carrying survey equipment, and when I went up there I marveled at the thought of a survey crew running high-precision levels to the top and back.

I would marvel too....

That is AMAZING!!!!

Thanks Stephen and Jim.

That level loop to the top of Mt. Whitney and back was a huge accomplishment. I'd definitely put that on my resume.

Dave

While it was not the norm for USC&GS to not stamp anything triangulation disks back in the 20s, it was also not especially unusual. David is right, the level loop up Whitney was quite a feat. I have a copy of the leveling report by William Bowie published in the Sierra Club Bulletin, February 1929. Anyone who would like a copy just drop me an e-mail and I'll be happy to pass it along.

> I have a copy of the leveling report by William Bowie published in the Sierra Club Bulletin, February 1929. Anyone who would like a copy just drop me an e-mail and I'll be happy to pass it along.

I'd love to have a copy. I don't see an email address for you, but I can be reached at jhframe[at]dcn.org.

Oops Sorry -- base9geodesy@gmail.com