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Finding Benchmarks


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If I had to choose between yes and no, I would have to say YES.


Benchmark hunting is one of those things that you will really be helped by reading the FAQ. And if our FAQ is not providing the details needed for someone to start looking sucessfully, please let us know. The two most important things for a beginner benchmark hunter (in my opinion) are:


1. Is the location adjusted (coords should be right on) or scaled (coords could be off by as much as 660 feet). However, in both cases, the description will help you find it because the description will give you details that coordinates can not.


2. Is the marker type some sort of building or structure? If so, verify that it is the same structure and confirm that the point used (as mentioned in the description) still exists on the building and call it found.


So, imbedded in both of my points is that the description is also an invaluable part of looking for these things.

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On a benchmark's sheet, look under the lines that give the Lat Lon coordinates and the Altitude. Part of the next line will say "location is". You want to note the very next word, which is either "Scaled" or "Adjusted".


The FAQ that rogbarn refers to explains what "Scaled" and "Adjusted" mean. Briefly, if the PID you're looking for says "Scaled", ignore the coordinates except to find approximately where to park your car, and use the description instead.


If you're interested in finding benchmarks, you should first read the entire FAQ. :)


Yes, they can be very hard to find. Unlike geocaches, it isn't always true that what you search for is really there - it may be gone now.


If you want an easy time with success as you begin, I suggest picking benchmarks that are "location is Adjusted" and have a found report sometime in the last 10 or 15 years. :D

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It can be anything from Trivially easy, to VERY hard. You go looking for a benchmark that has an adjusted location, in a good GPS sport, and you should just be able to walk up on it. Ones with GOOD directions that have not had too much change in their area since they were last found are also easy - I found one the other week that hadn't been found since 1952 - walked right up to it. It was described as "In the west wall 3 feet south of northwest corner, 2 feet off the ground" - yep the big massive building built in 1952 was still there, and so was the disk


The you go looking for some mark that hasn't been found in a while, where there has been massive construction - good luck - i t might be gone, might be burried, and all of the reference points are GONE - good luck. The first one I tried to find was like that

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I've gone out a couple of times looking for benchmarks, and have trouble finding them using the coords given...

:) I see you found one of each, scaled and adjusted. I noticed the adjusted one had several previous finders

who also were probably going by coordinates. However, YOU were the first to find PH2347 using the description! Good show! :D


I would suggest you take more than one picture of benchmark locations. Not only a picture of the disk, but one or more panoramic views to help others to easily locate the mark. Could be a picture from over the disk looking at an identifying feature (building, roadway, tower, etc.), or from another spot back towards the mark with identifying features in the background. If you read the guidelines from NGS, they do not want people in the pictures. Caption the pictures as to what direction they were taken.:D

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Here is my methodology to hunting benchmarks... I am not necessarily recommending it, but it works very well for me.


I use USGS quad maps extensively and bought a whole bunch at once directly from the USGS Store, which has them for $6 each, and shipping $5 for the lot. Then I go to the NGS website and retrieve all the datasheets for each quad at Datasheet retrieval by Quad. I save the web page as a .txt file, edit it to strip off the junk at the top and bottom, and run it through BMGPXto get a .gpx file. Then I open USAPhotoMaps and open .gpx the file I created, display the topographic map, and manually highlight all the benchmarks listed on my paper map. Next I edit the quad .txt file and format it to clean up the pages, print all the description sheets, put them in a binder in their own quad section, and I am ready to hunt! The books and maps stay in my car so I can hunt on a whim.


When I find a station I check it off on the map and make a notation on the sheet. If I can't find the station, and am sure I will never find it, I put an X on the map and make a not found notation on the sheet. Those sheets get put in a found/not found book. I make any notations on the sheet that might help to update the description and later use those sheets to enter my finds on Geocaching and NGS web sites.


If I can't find a mark I will often use USAPhotoMaps aerial photo capability to research the mark. Looking at the images often gives clues that aren't seen in maps, such as rerouted roads, new features, removal of features, etc. I have found a few (not a lot, but a few!) marks that way. And on a couple of occasions I have NOT found a mark, but was at least pretty confident I was looking in the right spot. Here is an example KW1220.


I have read a lot about paperless hunting in these forums and, despite being a computer professional, I don't really have any desire to drag a Palm or Windows CE device around with me as I benchmark. For one thing they are somewhat fragile devices and might not last long. For another, they are hard to read in direct sunlight. I would LOVE to have a laptop with me in the car with USAPhotoMaps on it so I can reference the aerial photographs. That isn't real likely though. And while it is possible to load a huge number of points into a GPSr, I am note sure how I would handle that, as my books encompass well over 1,000 marks and I tend to hunt randomly, either heading off in some direction and seeing what I can find, or hunting when travel takes me somewhere, such as my daughter's soccer practices. Where GPS IS handy is where reference points are vague, mentioning such items as 15 inch oak trees with triangle blazes, which are certain to be unblazed 50 years later and no longer 15 inch. A GPSr can get you close at least.


Any of you veterans do it this way? I would love to hear how others do it. I started doing it this way soon after I started and have refined it a bit, but not much. It works for me and I enjoy it, so I doubt I will change much (my car is a constant benchmark hunting mess between the maps, books, shovel, poker sticks, measureing tape, stakes, etc etc). But I also like to hear others' techniques too!



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I've been hunting for a little over a year and my success rate has improved steadily. I have come to understand one very important thing: the description on the datasheet is, assuming it is fairly complete and not inaccurate, the best way to find a benchmark. Recently, I have relied more on the datasheet and a tape measure than the GPS (although the GPS is a good tool, especially for marks with adjusted coords.)


Don't get discouraged. I've had my share of "one for 13" days, but I've also had a number of "seven for eight" days, especially recently as I've gotten better organized and prepared.


Re mloser's system: for the past few months I've employed a very similar system (though even lower tech) for organizing my searches. Plotting the marks on a topo gives you the ability to see very easily how to move about an area so as to maximize the number of searches for a given time period. I often add an additional step: I'll do a very crude drawing of the area as I understand it from the written description. If, for example, the mark is described as being in the northwest angle of a road intersection, 36 feet west of the centerline of the the N-S road and 54 feet north of the E-W road, I'll do a quick line drawing with those data. This is especially helpful if (1) you've got a notebook with a hundred or so datasheets in it and, (2) it's been more than a few days since you planned your hunting trip.



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I do a drawing sometimes too, especially if the description is complicated. That certainly saves time in the field trying to reinterpret the description. I do that in the margin or on the back of the datasheet so I don't lose it.


And my favorite part of hunting is finding the 'Not Found' previously ones. I am happy to say I have a number of these to my credit.



Edited by mloser
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mloser -


Here's my method:


1. I pick an area for a day's benchmark hunt and get a GC.com datasheet for a benchmark in that area and then click on "nearest benchmarks".


2. I go through the list of nearest benchmarks, bringing up each PID on the list. I check the box next to each that I want to look for. I end up picking about 15-25. (I may or may not get to them all during the day's hunt.)


3. I download from the GC.com site a .loc file of the group. If the group is from more than one GC.com page, then there is more than one .loc file.


4. I start easygps.exe and read the .loc file. I use easygps to save-as a .gpx file and I use easygps to transfer the lat-lons and PIDs to my GPS.


5. I have a .BAT file that extracts the PID numbers from the .gpx file using a pc version of unix's grep and a pc version of unix's sed (freewares). (It's a 2-line sed file). (This could be done manually too, or by using perl instead of grep and sed.) The result is just a text file of the PID numbers, one PID per line.


6. I go to the NGS's PID retrieval page and browse in it to open my text file of PIDs.


7. Using this NGS webpage, I get all the datasheets for the PIDs on my screen and save-as it to a text file. I make sure to sort the list of PIDs by PID.


8. I have another .BAT file that runs a 35-line sed script that reduces the datasheet file down to about 1/3 of its size by removing unneeded lines. (I don't fiddle with the format - I just delete some lines.) I can get 2-4 PID's per page in reduced NGS datasheet format that way.


9. I import the reduced datasheet file into a word processor and print it on paper.


10. Often, I use either GPS Visualizer or USAPhotoMaps to make a map of all the PID's in my group so that I can refer to the map and decide which one to do next after I finish with each PID. I just use such maps for planning my driving, not for finding the benchmarks - to find the benchmarks, I use the description for the scaled ones and the coordinates for the adjsuted ones.


So, with the printout of the reduced datasheets, and maybe a map of the benchmarks, and my GPSr stuffed with the PID's coordinates, off I go. During my search, I write notes on the printout - changes in to-reach instructions and maeasurements, and for the scaled ones, the time-averaged lat-lon coordinates that I get from the GPSr at the station.


Generally, I don't print out the GC.com datasheets any more because:


a. they don't include the reference mark distances and azumths (if they exist for the PID), and


b. paperwise, the printing is much more efficient with reduced NGS format, and


c. I only have to say "print" to the computer once, for the whole collection of PIDs., since they are all in one text file.


If I do use the GC.com datasheets, such as when the NGS site is down like it was last weekend, I don't use the mapping softwares because the maps on the GC.com datasheets are good enough to figure out the order of driving.

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That is something I have wondered about - I notice some BMs are listed on the topo maps and some are not - what criteria was is used?

BM are placed for different purposes. My guess would be that BMs used as reference points to create data to draw the map will be shown.

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The ones that are on the maps are placed there when they did the field work. Done by the field person annotating the map when he found the mark, they are predominately USGS marks. Much of the map work done in later years was with the use of temp help and may lack thoroughness. I recall running into a USGS map party here in Michigan in the 1980's. Most were college kids working for the summer with senior survey people. The maps teams we met up with was just a 2 man crew, a senior tech and his rod-man. He was driving a pickup and the rod-man has a dirt bike. They ran elevations down all roads and trails on the map. They had another crew that was setting BM's in some areas and those guys were all college students working for the summer. Also USGS had a habit of only looking for and using marks they needed and no more. One would think they looked for them all but no so. One of the guys who worked on that crew (when is was in this area) for about 1 year, never went to Mississippi when they left and came to work for our DOT. Said he was sick of working in swamps all the time. He was on the party that was mapping the Seney National Wildlife Refuge. He said the ground was so swampy that they had to use a Weasel (4x4 ATV) to get thru the swamps, the would park it and set up the level on the top it so as to see over all the brush. Still required men to cut brush as day long to clear lines of sight. They had a team of draftsmen in the field office plotting at the work on provisional maps. Appeared to be a good job but they lived like Gypsies all their life.


Once the map is field checked, thats it. They do not place all marks possible on the maps. So if the map date is 1972, anything since is not likely to on it.

Edited by elcamino
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Just use the directions.

The past few days, have been having a blast finding old benchmarks along the abandoned Denver & Rio Grande railroad. In most cases, the description hits the nail on the head which lead to the conclusion JL0043 had been destroyed. :(


However, in trying to locate KL0264, the dam, lake and roads had all been changed. By using the scaled coordinates, I was able to get to a point where a search of the area locate the benchmark. :D


Whatever works!

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In the lower left corner of a USGS quadrangle sheet are the credits. On most, but not all, maps is a line that starts with "Control by". It is followed by the agencies whose control is shown on the map. In my area, this is true for the older maps, but more recent map revisions have a statement saying that the survey control [is] current as of the date of the previous edition.

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