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3 benchmark items at one area?


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I was reading a description of a benchmark that I am going to try and find and was wondering about the 2 additional reference marks that were mentioned.Here is the part of the description I was talking about..."STATION MARK--STANDARD USGS TABLET STAMPED---BEND 1948 - VABM 4566---, CEMENTED IN DRILL HOLE IN BEDROCK. REFERENCE MARKS--STANDARD USGS REFERENCE TABLET STAMPED---BEND 1948--- AND CEMENTED IN DRILL HOLE IN OUTCROPPING BEDROCK, NO. 1 BEING 20.8 FT. FROM STATION, S 76 DEG 22 MIN E, NO. 2 BEING 28.2 FT. FROM STATION, N 28 DEG 31 MIN E"...would this be 3 seperate benchmark items,and should I get pictures of all 3 for my log post if I find this benchmark.Thanks.

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I am not sure exactly what "S 76 deg 22 min E and N 28 deg 31 min E would be direction wise.


Somebody smarter than me is gonna have to explain how to determine such directions with your hand-held GPS unit. I've always found an orienteering compass much easier to use for such tasks.


Basically, the first coordinate says: "Face due South, then turn 76 degrees, 22 min toward the East" so you're heading roughly ESE. The second, "Face N, turn 28 Deg, 31 min E" (heading NE).


With a compass for the first coordinates:

- Hold compass in its "ready position" - waist-high, squarely in front of you, as you'd use it for navigating.

- Rotate the circular housing so the 180 Deg (South) mark lines up with the index mark on the compass base.

- Rotate the housing 76 degrees 22 min easterly (clockwise) bringing the 90 Deg / East label closer to the index mark. i.e., 180 - 76 = 104 degrees -> the 104 Deg mark should be at the index mark. For practical purposes over short distances with hand-held compasses, getting within a degree or 2 (forgetting the fractions of degrees/ minutes) will get you close enough.

- Keeping the compass base in its ready position, turn your body until the N needle is within the "gate" on the compass face. You should now be facing in the correct direction.


For the second coordinates, step 2: rotate the housing so the 0 Deg (N) mark is at the index mark; then counterclockwise 28 degrees, bringing the 90 Deg / E mark closer to the index mark.


Remember you'll need to consider declination correction of the compass, also - more important as you measure off farther distances than the 20' & 28' distances in your examples.

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If you want help, it helps to post the PID for this benchmark. That's the number like AA1234.


You'll probably do better if you check the official NGS datasheet, which has a section informally called the 'box score,' where the distance and direction of the reference marks (which are, yes, separate disks) from the main ('station') disk are specified.




(edited to correct typo)

Edited by ArtMan
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skeezicks -


The system of bearing notation in that description is called quadrant notation. Quadrant notation starts with either N or S, then tells which way to go (towards E or W) from one of those as A tapeworm explained. To convert to the regular notation (azimuth notation), add or subtract the degrees indicated as follows:

N X E: add X to 0

N X W: subtract X from 360

S X E: subtract X from 180

S X W: add X to 180


So, in your example, S 76 degrees 22 minutes E : subtract (76 + 22/60) from 180 to get 103.633333 degrees. That means, if you are at the main station, look in the direction of 104 degrees to find the reference mark. As A tapeworm said, you must pay attention to the magnetic declination for the area where you are (if you're using a magnetic compass). If you are using a magnetic compass then you may wish to read this part of the Benchmark Hunting FAQ page that explains how to use the magnetic declination. Using the topozone link from the benchmark page that 2oldfarts (the rockhounders) found, the magnetic declination is currently 14.617 so if you're using a magnetic compass, look in the direction: 103.633 - 14.617 = 89 degrees (rounded off). That's pretty much straight E on a magnetic compass. :D


Since there's no official box score for this station, I'm not sure whether or not the quadrant information for the reference marks was based on true North or magnetic North. (Perhaps DaveD can help us here.) If it was based on magnetic North, you will need to use the declination site referenced in the first link I gave to determine what the magnetic declination was in 1948 and apply that. :D


In answer to your picture question, the optimal log in terms of pictures for a main station and 2 reference marks is to take and post 6 pictures. One closeup of each marker (the main station and the 2 reference marks) plus a 'distant' picture for each of the three, from 10 or 15 feet away, looking toward the disk to show how it looks in its surroundings. If you don't feel like doing all 6 pictures, the 2 most important pictures of the 6 are the closeup of the main station and its 'distant' picture.


For 'distant' pictures, it is sometimes helpful to also add to the picture's description which basic (like NE) compass direction you were facing when you took the picture.

Edited by Black Dog Trackers
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Others have done a great job coaching about "degrees" and "photos". I'll just put in a commercial for including the city/county and state in the photo captions, along with the mark's identification.


It makes it more interesting when folks browse the photo gallery.



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Thanks for the replies...that definately helps me out with both my questions.The one thing that is really challenging about benchmarking for me is when the gps coords aren't very accurate and I have to find them by the location description...but that is also what makes finding alot of these fun at the same time.I have one in particular that I found all the description information for,but believe that the benchmark might be just under the ground surface.I am going to take my metal detector out in a few weeks and try and find it...tons of fun looking for and finding these little pieces of history.

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