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pgrig

Need Surveyor Help, Please!

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The battle was well fought, and you should be commended on your efforts. Maybe another battle to come.....

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Paul

 

I would love to come down and help you on this one, but I'm tied up on weekends through mid-October. Maybe after that...?

 

In the meantime there is one more thing you can check. With a simple builder's level (the kind that sits on a tripod, not the long bar with bubbles in it), and a sighting rod or tape measure, you can determine the relative elevations of RM 1, RM 2, and the bottom of your hole. According to the datasheets, RM 1 = 97.9', RM 2 = 98.2', and the station = 99.2'. These elevations seem to have originated when the RMs were set in 1943 and should be accurate to the nearest 0.1'. If the bottom of your hole is still more than a foot higher than both RMs, you need to dig deeper. If the hole is lower than the RMs, there is a good chance the site has been altered by heavy equipment.

 

I'll take a look at the calendar and see if there's a date that will work for getting down there.

 

Bob aka Holtie22

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I was reviewing this excellent and fascinating saga and this question caught my eye...

 

2. Is there a simple "triangle-solving" calculator, like for doing a resection?

Good ol' internet .... Plane Triangle Solver.

No doubt there are more out there, I just checked out this one. It does the job, all right.

 

It's always amazing to me to see how much interest people (like the DCR folks) have in finding marks with us! :ph34r:

 

The datasheet for this mark has a reference to an underground mark - odd since the station mark is said to be mounted in a surface boulder (in a 1943 note by the NGS(!) ) or an underground ledge (the 1953 note). It seems that perhaps ledge=bedrock to the 1953 writer. Hopefully the hole is not 1" off the edge of an underground ledge. The LARGE BOULDER FLUSH WITH THE GROUND really must be somewhere there, unless they blew it up with explosives or somethning.

Edited by Black Dog Trackers

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Once again, thanks to all!

_____________________

 

Holtie22-- From memory (and mine's gotten pretty good for this site!), and a now extensive photo gallery, I am pretty sure that the surface of the parking is not more than a foot above the level of (surface-mounted) RM1, and I believe this is a generous estimate--actually, I believe they're within 8 in. of each other. (Of course, my eye for elevations [over a 100 ft. distance] is not well-trained.) So if the 1953 Description says the station is 12 in. down, that would be, say, 14-24 in. below the current driveway surface. My "Big Dig" of 9/22/08 went down a measured 28" and I then sunk the drill another 8" down in a couple of places. :unsure: .

 

My hope is that the underlying ledge (which is what I believe the mark is on) undulates like a wave, and we just had the misfortune to hit a "trough". [From my experience, folks who write Descriptions use the terms "outcropping ledge" and "boulder" almost interchangeably... :ph34r: But still, my expectations of success took a big hit after Monday's outing.

 

Still. my various resections were enough off of each other (1-2 ft.!) that I'd love to see what a real transit (as opposed to a Brunton-on-a-photo-tripod) can do! More learning for me! [When this is over, I'm going to apply for my Benchmarking Merit Badge!]

 

So yes, let's see if we can plan something next month. I've now actually got the Park people excited about finding "their" mark, so I think they'll be helpful again. How many sites do you visit where you have a huge power drill, line power to run it, and a 25 lb. iron bar at hand? [We actually hauled a 40-50 lb. boulder (false ledge) out of the hole we dug Monday.]

________________

 

BDT-- Thanks for the link to the triangle-solver! Following Papa-Bear's suggestion, I set my laptop up with a "resection spreadsheet" before going out on Monday, and I think it worked OK. And it let me know that Excel does indeed have SQRT and COS-ACOS functions. :lol:

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