pgrig

Mostly during the 1930s, but continuing up through the 70s, the Mass. Geodetic Survey (MAGS) set a number of reference marks using the often difficult to find "tack in lead," a copper tack embedded in a lead-filled drill hole in ledge. Here's a very distinct example. I've recently run into quite a few of these. Example sites include MY3451 and MY3453. If these marks have been weathering out in the open for a while, they are often quite distinct (resembling aluminum plugs), and tend to survive more often than benchmark disks (what kid gets a thrill out of digging lead out of a drill hole?). If they've been buried under soil or thatch for a few decades, however, they can be almost impossible to pick out from a background of dirty rock. I was wondering if these marks were unique to Massachusetts, or do you others run into them elsewhere?

After about a year using my Garrett Ace-250 machine (about $200), I find it's useful in perhaps 40% of the problem situations I hit. I usually set it for "All Metals" and use its "pinpoint" feature to see where it lets off the loudest signal. It seems to detect things down to 6" or more. Problem comes from its getting fooled by bits of metal trash that are so prevalent nowadays. As much as 1/8 of a cola can sounds like a benchmark disk. Rather small scraps of tin foil, pull-tabs, etc. set it off, and are hard to discriminate from disks. Also it seems to "miss the mark" quite often by 6"-12". This may not sound like much, but if you're digging down 6" through hard terrain, it's a pain! I usually use it only as a last resort, when taping is very hard or measurements have been made but are inconsistent (or logically impossible). But it has found me a significant number of marks that otherwise would have remained hidden. [Particularly memorable was a disk that was planted for one of the old Nike missle sites that used to ring Boston but which have now been replaced by subdivisions, wiping all tie-ins and RMs away in the process.] Now if they would only make a machine that would detect a "drill hole in ledge," I'd be a happy man....

If the blazes on the trees only identify them as RMs, what's the problem with re-blazing them if time has caused the blaze to "heal up"? This doesn't seem to me to be anything like "restamping" a station mark. It only helps to identify a RM and has no "geodetic" significance.

Hi Patty-- I would think the CIA would be battering down our doors seeking our expertise in "related fields." I'd like to say more about the interest your posting kindled in me, BUT: The Company says: " Friends, family, individuals [benchmark-hunters], or organizations may be interested to learn that you are an applicant for or an employee of the CIA. Their interest, however, may not be benign or in your best interest. You cannot control whom they would tell. We therefore ask you to exercise discretion and good judgment in disclosing your interest in a position with the Agency. You will receive further guidance on this topic as you proceed through your CIA employment processing." In other words, I could tell you, but then they might have to shoot me.

Awesome data display! (I like the bar graph a lot!) 1. It's a relief (at least judging from their reports in MA) to see the Power Squadron reports disappearing. They must have stopped giving out "points" for these.... 2. I'm really impressed with the role played by us geocachers! Do these reports include only those actually coded with GEOCAC at the time the NGS report is made, or are there other ways to identify geocaching inputs? 3. Interesting to see that the level of geocacher (a bit odd to be called that; I've never even seen a geocache) activity has remained relatively constant at say 800/mo. for the past three years. 4. Does this mean that NGS, state geodetic agencies, and other mark-setting entities rarely conduct station status visits anymore?

Nice write-up by NGS. Just one complaint. NGS said "the monument provides a mechanism for geospatial professionals (land surveyors, engineers, etc.) to access this framework ...." Wouldn't it have been easy to add "and benchmark-hunting hacks" after the ) ? Aren't we, even with all of our faults, entitled to a little recognition once in a while? Maybe Holograph knows the answer to this one: of the total of all reported recoveries of NGS benchmarks in a recent year, what percentage are attributable to us?

Sharp eyes, Shorelander. Please tell me the little-used penalty of $250 will be exacted from the seller. "We don't know how we got this" indeed! May he be hung by his thumbs from that last-remaining Bilby tower in LA until bitten to death by mosquitos....

OK, so there goes my crop circle theory... (beautiful old photo, by the way).

Good find! I'm pretty sure your image is like a benchmarking crop circle. Have there been any reports of small, weird flying disks hovering over likely-looking boulders? And are you sure about those stories of NGS staff "bringing in" the boulders from elsewhere? Has anyone ever seen them lugging boulders around? I rest my case... -Paul

First, I have to confess that I've been out here on GC.com a little more than a year without ever being aware of "The Gallery". You get to it by clicking the [Visit the Gallery] link, which is right next to the [Discuss in the Forums] link on the Benchmark Hunting home page. What it gives you is a serial display of all the images that members have posted recently as part of their logs, in date order. (After a certain point, the display "rolls over" to ignore the oldest photos.) This is fun, because it shows you the incredible variety of settings in which we all work--deserts, mountaintops, railsides, and town squares. It also gives you an idea of things you can do to improve the images you attach to your logs (like it would help if I attached the PID to mine...!). The Gallery presents your posted images in the reverse of the order in which you posted them....). Clicking on a Gallery image takes you to the log page for that station. I can't believe I missed this!

m&h-- In the last couple of trips, I've had several of these SOTR (Somewhere Over the Rainbow) reference mark sets, and I'm developing the knack of finding them, as with this site, which I'll log soon. By the way, are you local to me? -Paul

Hi cjz here-- For an explanation, take a look at the "Scaled Marks" thread just below. The Description of your mark seems OK, but as you discovered, its stated location is way off. This is characteristic of many of the Scaled (as opposed to Adjusted) marks we hunt. A helpful thing would be, once you find it, to include its actual coordinates (as measured by your GPSr) in your log, which previous folks who have logged this mark failed to do. -Paul

__________________ I find this thread very interesting! The quote above by m&h actually hits the crux of my initial question, which, boiled down, asked, "How can a mark be useful if we don't know where (horizontally) it is? And my concerns were heightened (good pun, huh?) by the fact that most of the scaled marks I have hunted have had really sloppy directions, so sloppy as to render many of them virtually unrecoverable. It often takes me hours for one of these, or a hunt equivalent to finding (and documenting) a tri-station with three "copper pin in lead" RMs which have neither direction nor distance described on the Datasheet (from the website . By the way, is this phenomenon, the reporting of "cloaked" reference marks, characteristic of Mass., or do others of you get to experience the joy of hunting these down? [see, for example, MY2758.] I was not trying to somehow demean the scaled mark, or to give it some sort of second class citizenship, and it's interesting to see that many folks consider recoveries of these to be more valuable than recoveries of tri-stations. And I only resort to "shooting a few ducks in the bathtub" (which to me means going after roadside stations set by the Mass. Geodetic Survey in the 1970s) when I've emptied both barrels at a particularly stubborn scaled mark with no success. By the way, is it proper to call a scaled bench mark a "station"? Thanks for all the interesting comments! -Paul

Hi Patty-- Just a pat on the back for you from Boston. I've noticed that you are often the one who gives the first, fullest, and friendliest response to newcomers who ask basic benchmarking questions over here. For what it's worth, I commend you. This is also meant to buy me forbearance with my next less-than genius question-post. -Paul

Thanks, all. OK mloser and seventhings. Your "temporary re-set by field party" was my last guess above, and I suspect the correct call. I've just never seen this in my lengthy (1-year) career! :-) By the way, the drillhole for this mark would appear to be the standard size and (I suspect) depth. It's just one of dozens of 1934 MAGS disk installations around here. -Paul

Thanks, t8r. But I don't see how prying out the stem (which I don't think happened here) would leave material that looks like my Detail photo where the stem used to be.

Most of mine requiring detail have the long dimension set at 600 px, or sometimes 630 if I push it. Above that, I believe resizing by GC.com sets in, and that can cost you quite a bit of sharpness, I believe I recall. Simple closeups of disks that are well-focused I can get away with at about 450 px on a side, if I recall correctly.

Hi All-- On Benchmarking Opening Day, 2009, I visited MY2792. Please take a look at my MY2792-Detail photo, or the detail photos by Munin (6/28/05) or ddnutzy (5/1/05). I'm wondering what this is. At first I thought it was an ordinary "only the stem remains" station. But what remains at the "stem" location doesn't look much like bronze disk metal. Rather, it looks like some sort of weathered-down, pitted compound, which had small, entrapped bubbles. And it seems to have been center-drilled. The photo by ddnutzy even appears to show a small pin located at the center of the "stem" (similar to that in the early 1930's reference marks set around here by the Mass. Geodetic Survey (MAGS), which monumented this station in 1934). The Datasheet shows a Recovered-Good entry by MAGS in 1978. Today you can clearly see what looks like old disk cement around the "stem", and a faint outline of a former disk in the rock itself (shows nicely in Munin's photo). No resets are mentioned. What's going on here? Do bronze stems ever weather-down to this? Did some disks have a center hole running down their stems? Is this an unlisted reset of some sort, with only a center pin (or compound) re-set and the actual disk not replaced? Something else?

As I start out on my 2nd year of the GBQ (Great Benchmarking Quest), I was planning a few Scaled marks for an early trip when this question hit me: "Why do we bother with these suckers at all?" Here on GC.com we engage in lengthy discussions (which have helped me a lot!) on whether to accept this or that Adjusted mark as Found or Not Found, based on complicated assumptions concerning their precise history, placement, and stability, or lack of same--usually accompanied by arguments that the slightest displacement (or mis-location) of these marks over time renders them useless for practical purposes. But the NGS database contains (and we hunt) Scaled marks that have no practical location whatsoever, often turning up many hundreds of feet distant from their (admittedly imprecise) officially designated positions. I suddenly realized that I don't understand why Scaled marks are even carried in the NGS database at all, or have any practical utility. Are they in fact marks that were initially set with precise locations but for which precise location data were lost in the mists of time? [i believe that I know that Scaled marks are useful primarily for their elevations, but how useful can this be if we don't know precisely where they are on the ground?] Would one of you Great Ones please enlighten me? :-) Many thanks, -Paul

No problems here (Firefox 3.0.8 and XP Pro v. 5.1 SP3 behind a H/W firewall), nor did I see any over the past 4 or 5 days (since Harry's original post), while I've been in and out of about 40 different marks and perhaps 75 photos.

I would like to add Paul's Principle to the scheme laid out for Paul-PFF's otherwise excellent probability prediction machine, to wit: "If mark was reported as set more than 6" above the surface of the roof (e.g., on top of a parapet), add three points, unless located in New England, in which case, deduct those three points, and three points more, since mark is likely covered with tin flashing and ample amounts of roofing cement, from previous attempt/s to stop leaks into school caused by ice damming, etc. "If you have successfully bribed the custodian to gain access to the roof, but have neglected to bring along a heavy iron prybar for peeling back tin flashing, deduct 5 additional points. DO NOT ATTEMPT TO SALVAGE YOUR "'FIND" BY ATTEMPTING TO PEEL BACK THE FLASHING BARE-HANDED; flashing causes deep, ragged gashes in your fingers." MY2594 would be a good exemplar of Paul's Principle.

Marvelous job! Down a lazy river..dum de dum, dum dum....

Patty-- That would give me credit for knowing how to drop Groundspeak a note... I will now figure out how to do that and message them. -Paul _____________________ Edit: OK. I emailed them.

I'm not sure what's going on here... Recently, when I click on a Google Maps link at the right side of a Details page for a benchmark on GC.com, I get a "we could not understand the location" error page, next to a national-level map of the US. This is apparently because GC.com (?) has started inserting successive open- and closed- parens characters [like this: () ] at the end of the lat/long string. If I edit out these characters, it works fine. Is this something my computer is inserting into the lat/long reference? I'm not sure if this happens all the time or just every now and then... Thanks, -Paul

Thank you! Andylphoto--That sounds doable; I already include at least a "Detail" (C-type) photo and an "Area" (A-type) photo with each of my GC.com reports. But how do you send them to Deb? As individual e-mails (like I do with Destroyed stations)? Does this mean if you file 10 NGS reports she gets 10 emails, each with two or more JPEGs attached? (What a pile of e-mail on her end!). And what do with think she does with all these? Also, my Area shots are starting to include a fair amount of info added to them via SnagIt--they come out looking something like this. Does this make sense? -Paul