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Benchmark Secrets


Toby Tyler

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Along with finding geocaches I am interested in finding the benchmarks in my town and in the area. I have found one so far but they seem so elusive. I guess I like the feeling of finding something that other people have not paid attention to, cared about, or even knew that was there.

 

My question is, what is the secret to finding benchmarks. Is there even a secret or is it just hard work and determination? How about tips for location.

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Along with finding geocaches I am interested in finding the benchmarks in my town and in the area. I have found one so far but they seem so elusive. I guess I like the feeling of finding something that other people have not paid attention to, cared about, or even knew that was there.

 

My question is, what is the secret to finding benchmarks. Is there even a secret or is it just hard work and determination? How about tips for location.

 

1st check the coordinates on the benchmark page. If it says "scaled", then the coordinates can be off by as much as 3/10 of a mile. Typically they're off from 200 to 500 feet. If they are scaled you MUST go by the description of where the benchmark is located.

 

If they coordinates are "adjusted" then your GPSr should get you within 10-15 feet.

 

If you need more help, feel free to ask for help in the benchmark hunting forum.

 

John

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I guess I like the feeling of finding something that other people have not paid attention to, cared about, or even knew that was there.

This is precisely what has gotten me interested in this recently. I have a general affinity for things forgotten, ignored, or just not noticed by the rest of the world whether they are buildings, bridges, and now even lowly benchmarks.

 

There's just something cool about seeing the world from a little different perspective than most people.

 

Sorry, I have no helpful advice as yet since 've only just begun hunting them myself. But I thoguht I'd share my take on it. :)

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I'll echo the previous suggestion about visiting the Benchmark forum (www.geocaching.com/mark) and reading the FAQ. Also tour the gallery so you can see examples of benchmark types and typical settings.

 

Two comments:

 

*There is no need for "stealth" in benchmark hunting. Relax and enjoy it. Enlist the help of the public, if you wish.

 

*Your contributions (recovery notes) actually can help professionals in the surveying field. About one hundred individuals throughout the United States visit benchmark locations to verify continued existence of the mark and to write a new "To Reach" description, if needed. Several times I've been stumped by an out-of-date description, due to road changes, grading, building destruction, etc. Then I spot a recovery note on geocaching.com and it clears up the mystery. Soon, a revised description is added to the government's data base, and others benefit.

 

May I add a third observation? Folks with 50+ cache finds are awesome when it comes to locating benchmarks. I've had the pleasure of watching several guys and gals go after elusive marks. Hunting for mini's and micro's seems to give folks a "sixth sense" about where to look.

 

Two things are Standard Operating Proceedure for me:

1. If you can't figure out how to put batteries in something, stand on the sidewalk and flag down a 12 to 15 year-old kid. They'll get the batteries installed, power up the device, and program it for you!

 

2. If a benchmark is "eating your lunch", just ask the local geocachers for help. They seldom miss!

 

Summary: Look up a few benchmarks and give them a try. I know you'll be successful, and I'm pretty confident you will enjoy it.

 

-Paul-

Raleigh, NC

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Like mentioned earlier, explaining that your hunting a Benchmark is much easier than explaining Geocaching. If you say: "I'm recovering a National Geodetic Society Survey Marker." People will probably leave you alone.

 

I haven't done much BM hunting recently (Been after caches too much ;) ) but it is really fun and you feel kinda like your doing something helpful. :rolleyes:

 

Edit to add: The Benchmark hunting forums are great, PFF, the rockhounders, and several other knowledgeable folks will help you out there.

Edited by Airmapper
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The other thing to remember is that the coords are in the map datum NAD 83 for benchmarking while geocaches are in WGS 84.

 

Your gps likely has the ability to change the map datum so that you end up at ground zero more accuarately.

 

Just remember to switch back to WGS 84 when you go looking for caches again!

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I set my unit on NAD83 and leave it there. We have had long discussions of the difference. I think the answer is that right now nobody's handheld unit will show a diffence in the US.

 

If the technology gets better in the future, NAD83 is the correct one for benchmarks, and it will still be close enough for geocaching. Consider that most geocaches are placed where reception is bad and you don't get the potential accuracy of the device anyway.

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Along with the other advice, here are a couple things that have tripped me up in the past-

 

Know what you're looking for. If it's a "copper bolt", go look at some photos in the gallery to see what they look like. You can tune your mind so a bluish green fuzzy knub stands out like a sore thumb. If you're looking for a survey disk, see if you can find a picture of a similar one in the same area. Remember, you have to find the exact disk, with the exact name and date stamped on it.

 

Know where they typically put things. Around here, survey disks are typically put in the center of cement drain culverts (except when they aren't). Copper bolts are typically put about one foot from the end. This can save a lot of digging and clearing away because you start in the right place. It's no guarantee, but statistically it help. I found a bunch of copper bolt marks that nobody else had found just by knowing where they'd likely be.

 

Carry a plain old magnetic compass. I like the flat clear plastic ones for hiking. Read the description of the benchmark about ten times and note the direction of everything. When out in the field, check directions often. I hate to admit it, but I've spent a good half an hour searching for an obvious mark on the wrong side of the road because I had a preconceived notion of where it should be. Use your compass!

 

Take advantage of the on-line aerial photos and topo maps to get a feel for the area, then use the description to make a sketch of where the mark is, and what the important distances are. Sometimes all the original landmarks will be gone, and you'll have to recreate the way things were up to 100 years ago. This is the part I like best :lol:

 

Post a bunch here, and get half a dozen finds under your belt before trying to file an official UGS report. It's easy, but there's a certain style and a few rules to follow so it looks professional. I have a bunch filed now, but am still working on looking really polished. What you want is for someone who actually has to use the mark, to follow your description, walk up to the mark in 30 seconds, and say, "man, that was easy."

 

Above all, have fun and try not to become too addicted.

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The other thing to remember is that the coords are in the map datum NAD 83 for benchmarking while geocaches are in WGS 84.

 

Your gps likely has the ability to change the map datum so that you end up at ground zero more accuarately.

 

Just remember to switch back to WGS 84 when you go looking for caches again!

For the purposes of geocaching and benchmark hunting with a recreational GPSr, the NAD83 and WGS84 datums are identical. There is no real need to switch the datums to hunt either caches or benchmarks. The positional differences between the datum origins is relatively small (<3') and should only be of concern if you are using high precision, survey-grade GPS equipment.

- Kewaneh

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get a little metal pole and probe the ground within 10 feet of the GZ. You will probubly find it. I even use a nearby marker flag to probe the ground.

If you have a bit of spare cash a metal detector would work well too, especially one that can discriminate between different metals.

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Get to know what the witness posts look like in your area.

 

Witness Post? What's that??

 

A witness post is sometimes located near the benchmark, and is used to help find the mark. Check the data sheet for the distance and direction from the witness post that the mark might be.

 

Most new NGS witness posts are orange carsonite, and will have a NOAA sticker affixed to the front. You will need some practice to tell these apart from the orange carsonite posts that are placed to warn people about underground cables and phone lines (you certainly don't want to probe here!).

 

The older witness posts were white metal signs attached to a t-post.

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Photobuff has disclosed several very excellent items of experience and benchmark hunting wisdom. I do all the things he said (as do most/all of us). I do some other things, as well.

 

I try to "find" the mark before I even leave the house. I print the datasheet and read it very carefully taking note especially of what the mark is, how its monumented (flush, sub-surface, vertically, etc), and what its accessibilty is (road right-of-way, private property, curb, wall, etc.) I usually sketch a simple schematic on the sheet: if the mark is described as being in the southeast angle of the intersection of Smith St and Jones St, for example, I'll check the alignments of Smith and Jones (Microsoft Streets or Google Maps), draw the intersection and "plot" the mark's location with notations as to distances from curbs, street centerlines and utility poles, etc. For marks in rural areas, I'll print a Topozone sheet and "plot" the mark as best I can from the description (NOT using lat/long). Then, I'll load the coordinates into my handheld.

 

The whole idea here is to avoid trying to figure out where the mark is while approaching it in the car. You can't (well, I can't, anyway) analyze a datasheet while navigating, driving safely and trying to find a good place to park. I use the handheld's GOTO function to tell me when to start looking for a place to park. I never (seldom, actually) use the GOTO to find the mark.

 

Finally, when I get out of the car the first thing I do is to get myself oriented to N-S-E-W. Next thing, take a good look around for a witness post or orange ribbon: if you see them, the game should be over in a few seconds. If there's no witness post, I go to where I think the mark is with the datasheet, a tape measure, the handheld (for the compass function) and a weeding-tool probe. If I don't find the mark within about one minute, I get the metal detector out. If I don't find the mark in about three minutes, I step back, survey the situation and re-read the datasheet. If I haven't discovered that I've made some sort of mistake (like, I'm looking north of the utility pole rather than south), I generally pack it in. My overall "find rate" is about 75 percent. My "find rate" for marks that I don't find almost immediately is approximately two percent.

 

I may take three hours to drive to a mark and another 20 minutes walking to it's location and I'll dig for 15 minutes without hesitation (if I'm sure of the mark's location). But only very rarely will I spend more than five or six minutes actually looking for a mark.

 

A note on the "find rate" - about 10 percent of the marks I look for are the "unfindables" - predecessors of RESET marks and marks previously unfound by the NGS and/or professional surveyors. If I excluded them from my list of things to do, my find rate would be higher.

 

Hope this is of some help.

Will

 

p.s. - Very very important - also check the current version of the NGS datasheet before starting out. Do NOT use the "view original datasheet" link on the Geocaching datasheet - it's five years old. Go directly to the current NGS datasheet via the NGS site. There's often more info and more current info on the NGS datasheet. For marks with complex descriptions, I'll print the NGS sheet, as well.

Edited by seventhings
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You may want to bookmark this web page:

 

NGS Datasheet PIDS Form

 

Once at that web page, you can find the most current datasheet for the marks in which you are interested by simply entering the PID("s). (The PID found is found at the top of the Geocaching page for the mark following "Details for Benchmark:" It is 2 letters followed by 4 digits.)

 

Also, it is recommended to read the Me First! topic in this forum for answers to frequently asked questions and for some other tips.

 

Happy hunting!

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Instead of carrying a metal detector with me, in my back pockets are two 16 inch long copper rods(bent into a sidewards L. stick short end loosly in hand hold about 6 inches in front of me and where they cross do a little scratching of the bround with rock hammer and bingo benchmarks are found , geo caches under rock piles and pine needles and twigs and letter boxes.....

 

Of course all people for some reason are unable to do this. its kinda like witching for water.......

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Interesting. I carry "dowsing rods" as standard equipment. As a REALTOR who works with a lot of rural property, I often need to find the septic tank drain field on a property. The rods do a good job for me.

 

I had not thought of trying them on benchmarks. I'll report in after the next expedition! :-) But see my post "Buried Magnets" about the possibility of using a standard magnetic compass to locate a benchmark.

 

-Paul-

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