survey tech

I agree with you in general, except that I think its best to set out to prove, rather than disprove, the existence of any point. If the area is so different that the description is worthless, then no absolute conclusion can be made, GPS or no GPS, although it may be hard to imagine how the marker could have survived, some have in such cases. Im sure a lot of people do have misconceptions about the capabilities and eccentricities of GPS, but thats all just part of the learning experience, and no harm is done as long as no one gets the idea that knowing a little bit about markers and coordinates makes one a surveyor. I have been in the surveying industry 20 years as a technician and I am not qualified to call myself a land surveyor. Most people do not realize that the biggest part of becoming a land surveyor is not merely knowledge of the mathematics but a thorough and complete knowledge of the law. Anyone can punch buttons and generate numbers, being a successful surveyor requires a far rarer skill, superior judgement.

True, these points were not set for enjoyment, but the hobby has caught the interest of a number of people, and hopefully, through enjoyment they will learn to respect, appreciate and perhaps even help preserve what remains of the original control network by passing the knowledge they come across here along to others. All the technical info is really irrelevant, since the purpose of improving the descriptions on this site is to advise other geocachers and any benefit to surveyors is a mere by product. The chasm between handheld GPS and survey grade GPS has been explained here many times and I dont think anyone here has any illusions that just because they have learned how to find markers means they are ready to go out and start surveying.

The triangle is the universal mapping symbol for any type of randomly located survey control point, which includes all geodetic markers, whereas the square is used for points that are not set at random locations, such as boundary corners. In fact, many surveyors refer to random control points as deltas, due to the shape of that letter of the greek alphabet.

Thats an especially good one all right. You may search for years without finding an older one of the disk or cap type. The oldest stamped marker I have ever found also dated from 1906 and I believe that may have been the first full year they used markers of that type, although they may have started using them on a limited basis earlier, so there may be some a few years older out there somewhere.

Pictures are fine, but they do not really prove anything. One could extirpate a marker and then take a picture of it and claim it was already out of place to justify removing it, but hopefully no one here would be inclined to engage in this, and if they did I suspect they would draw stern condemnation from the community. Finding a destroyed marker just laying around is rare indeed. Construction crews, who most frequently destroy them accidentally, usually dispose of the evidence as soon as they notice it to cover up what happened, and those that are left lying unnoticed are typically soon reclaimed by a surveyor or engineer working in the area. So anyone claiming to be discovering them destroyed on a regular basis may be worthy of suspicion.

Opinion varies widely, but as I understand it, the NGS policy is that it does not expect disks to be returned and you are welcome to keep it. If you do not want to keep it, take it to the nearest surveyors office and tell the surveyor the conditions you discovered. If you do not want to bother with transporting it, write the surveyor a note and he will probably look into it. Of course, all this applies only to markers that are already completely dislocated. If its still even partially in place, leave it just as it is

The crux of the difference is that the NGS points are specifically intended for public use, whereas any points set by private companies or other agencies are a part of the specific project they were set in the course of completing and are therefore proprietary data. One could no more expect such data to be published than one could expect McDonalds to give away burgers for free. The reason for not releasing the data to the public is purely economic and has nothing to do with any desire to keep it secret. In fact the data is routinely shared between government agencies and private companies working cooperatively on all types of public projects. If you happened to know someone working for the Caltrans engineering department, for example, they could print you a list of coordinates that would keep you busy hunting for life.

The better the description the more useful it is. There will always be plenty of remote markers for others to pursue if they feel like a recently recovered marker is not worth visiting. In fact, it probably wont be long before it will be difficult to avoid repeats without going some distance.

There are enough people here now who know the basics that you should be able to get any terminology questions answered quickly. (And maybe even correctly!)

Rebar has gradually replaced iron pipe as the most commonly used material for property corners set by private surveying companies. More are now capped than in the past, but most are still set without any type of cap. Just be careful not to trip and fall on one, people have been impaled that way.

Probably well over 90% of all benchmarks are not in the NGS database, mainly because they have rigorous standards that make it very time consuming for surveyors to comply and also because state, county and city data serves the same purpose.

If it were an above ground mark there would be some reference to its height. If its still there and not within the fenced area, it sounds like it should be an easy find using the distances given from the objects.

Thats right, it is or was a typical ground marker. The original was probably in a round concrete base and the reset in a square base. The underground mark is irrelevant since you would not see it anyway. Its an example of the fairly rare occurence of a marker being reset in precisely the same position after construction. The note says that visibility from the spot was no longer very good, so its possible that it may have been deemed not useful enough to reset again, and was probably replaced by an undocumented point somewhere else in the vicinity at a better spot. If you are saying that there is now a tower on the spot and the pump house, transformers and fences are all gone, this is likely to be what happened.

With respect to the use of black versus brown on topo maps, black is used for what are called hard elevations, meaning an elevation on a solid permanent object, usually noted with an x for a monument or other small object and without an x for larger objects, like paved road intersections, while brown is used for what are called soft elevations, meaning an elevation on plain ground like dirt, grass or sand. Soft elevations are usually calculated by interpolation, such as contour lines, rather than being precisely determined by direct observation and are therefore not precisely repeatable or recoverable. Brown is also used for unchecked or approximate elevation data, such as aerial photography that has not yet been verified on the ground, and is, for that reason, sometimes the prevailing color on maps in areas where ongoing revisions are being made, known as provisional maps, along with purple, which represents new structures. Provisional maps are fairly common in sparsely developed areas, such as Alaska and the Inter Mountain West, but relatively rare elsewhere. For those not already familiar with the symbols, an x is used for elevations, a triangle is used for geodetic control points and a square is used for boundary monuments

There may or may not be anything to fix, depending upon what exactly has transpired since 1961. The original disk, which would have been stamped 1932, was probably destroyed by improvements to the steps during the 40s or 50s. The second disk was apparently set in 1959, but was already displaced when visited in 1961, and was reused at that time. Each point is entirely separate, even though they have the same name. The reset designation is intended to indicate that the original is gone or undiscoverable and the new point is intended to replace it. This is standard practice in cases where the spot is especially useful and resetting is merited. Reset points are hardly ever in exactly the same place, as in this case, where the new point is 0.6 feet, which is about 7 inches, lower than the old one according to the data sheets, which may seem insignificant, but is actually highly important. It is possible that the current disk may not now be at the elevation given on the datasheet, if the steps have been rebuilt again since 1961 and the same disk was improperly replaced in the new steps at that time, but this is unlikely, and even if it were the case, all local professionals using the current disk are probably already aware of its history and have compensated accordingly in their work.

Embra Deb Brown at NGS has previously pronounced others like V 12 destroyed, so technically that is the appropriate description in your case, but as I have mentioned before, the fact that the shaft remains, positively identifying the spot, means that the spot is still potentially useful for some purposes, and many surveyors would not consider it destroyed. The NGS treats the disk, or other object, itself, as the whole object of the description, largely discounting the continued presence or condition of its setting or mounting, while most surveyors, motivated more by practicality, are more willing to accept the spot, sans disk, provided it can be positively identified and there is no reason to believe it has moved. The important principle to remember is that the destroyed description is not appropriate in any case where speculation about the actual presence of the marker is employed, such as the one above, which may or may not remain in place beneath the concrete slab.

El Camino is correct, the spike is unrelated to the NGS disk. Its a typical example of a new point being set near an old point by a local surveyor when he dscovers that the old one is no longer useful. By the way, since the old point is almost certainly still intact and merely covered up, it cannot be verified that it is destroyed, so the appropriate description would be not found with an explanation of the circumstances.

Crews were typically assigned areas and were generally expected to report on the status of all markers in that area. Some crews interpreted the instructions to mean that they must file some kind of report on every existing marker including those they did not have the time or the need to visit, indicating, at least, the mere fact that they did not have occasion to use those markers, while acknowledging them rather than simply ignoring or overlooking them. This practice was more common in the earlier years and faded away as the number of markers increased to a point where it was no longer feasible to make note of all of them in a given area. In most cases, recovery notes prepared by NGS personnel state whether a search was made or not. The moral to be gathered is that a good benchmark hunter always sets out operating on the presumption that a marker described as not found does still exist until the contrary is proven conclusively. This is the reason for the traditionally strict limitation on the use of the description destroyed, because it is a conclusive finding, whereas not found is inconclusive. Many here have already discovered that not found, particularly when listed by the Power Squadron or other amateurs, is not to be trusted and therefore meaningless.

Go to ngs.noaa.gov and click on "our history". There are links to thousands of documents and photographs.

You guys are right that the history of these points is what really distiguishes them. Those in Virginia may be walking in the footsteps of Washington and Jefferson, and those in Illinois of young Abe Lincoln, all of whom were surveyors.

Make certain that the markings exactly match those given in the description in each case, otherwise you have probably found some newer points that happen to be at or near the described location. Even if the name and date stamped on them matches, look especially carefully to see if the word "reset" is stamped on any of them. This occurs fairly often, because certain areas are more useful than others and when a point in such a place is destroyed another marker is usually set, sooner or later, in that same area, but very seldom in the exact same spot. If they are the original points, its likely that they have been included in a local database. Remember that the "not found" status of description is not intended to indicate that the points are no longer in existence, but merely to indicate that they were not visited at that particular time. Often it simply means that they were not used during the work done in that year and they may not even have been looked for by that survey crew, unless it is specifically stated that a search was made without success.

The truth is that the local professionals who really need to know about the point you found probably already know about it. Unless there is some reason to suspect that the point is in danger of being damaged or destroyed, there is no urgent need to contact anyone to provide further info about it or add it to the database. If you find a large number of undocumented points like this in your area, you could create your own local database and then turn it over to a local surveyor, since it is possible that some such points may locally be erroneously believed to have been destroyed.

BDT I agree that the picture of the Latham Tank does not match the description and it cannot be assumed that it is in the same place as the original. To answer your question, yes, surveyors can also use cylindrical tanks as targets. From a distance of several miles, the width of the tank is not a factor. The center of the object is sighted, so any small object on top, marking the exact center, probably could not be seen anyway, and so would be of no help. The exception to this would be those tanks with a light on the top center, which is helpful, allowing it to be used at night.

Those with any significant amount of experience agree that in most cases a person using only a description will reach their objective more quickly and easily than a person using only GPS. On the other hand, this game/hobby would never have come into existence if not for the fact that it constitutes a valid GPS application. The goal, ideally, of participating, is to learn about both traditional surveying technology and GPS technology while safely engaging in an enjoyable outdoor activity.

High Precision Geodetic Network (HPGN) & High Accuracy Reference Network (HARN) are terms used to describe densification projects at the state level, in which state of the art adjustments are performed on existing points. Densification is the process by which various surveyors have, over many decades, put flesh on the bones provided by the original NGS points, increasing the total number of control points exponentially. In California, the process is particularly tedious and literally endless due to virtually constant displacement of the points by earthquakes. Visit the California Spatial Reference Center website for further info.