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Everything posted by jwahl

  1. They published a fairly unrepentent modification to their story about a week after the initial story.
  2. ETVA guess would be "Electronic Traverse Vertical Angle" which might be their name for trigonometric levelling with EDM. - jlw
  3. Holes were usually drilled with a star drill or various somewhat portable gas driven drills if you could afford one and probably after 1920 or so. My guess is that someone decided to 'try' a circular diamond bit and it wasn't working very well so they abandoned the effort. If they had a gas powered drill it may have broken down at that point. It could also have been that it wore out quickly at the depth shown. Other problems I can imagine are that once you had a circle drilled a half inch deep or so it would seem to me it would bind against the rock. And even if you were successful in going 3 inches deep, you would still have to chisel out the center material. Surveyors have had various small gas driven drills for quite a few years if you did this a lot. I used a fairly large one about 30 years ago I only remember the name "WACKER" on it which may have been a manufacturer. It would drill a really nice 1.25" hole very quickly and looked like the proverbial jack hammer. It weighed about 90 lbs. and would be about all you could carry over your shoulder. Sandstone would practically vaporize under it. Another brand commonly used was called a Cobra and the name Pionjar rings a bell too. Cobra Drill Modern Model Here is one that isn't working that well compared to the Cobra, but looks like it is drilling with a cylindrical bit I have seen drill holes all over the place in Rhode Island that are used as monuments and property corners. These had to have been mechanically drilled with some gas driven device. I suspect that practice is true thoughout New England. Except for the one project where we had the "Wacker" mentioned above most of the disks I set in rock were set in a hole drilled with much arduous labor with a star drill and a 4 or 5 lb. hammer. - jlw
  4. I noticed that the bogus article's author came on to the Utah Geocachers Forum 4 days before he/she published the article asking a lot of leading or misleading questions. The questions reflect incorrect assumptions and so it is not surprising that incorrect answers were given. I saw this phenomenon also with a number of experts that appeared on newscasts for this story. There were two alleged Utah historians who apparently don't know where the Boundary was supposed to be or in fact ANY history of how any of the boundaries were established. Some appear to just be making stuff up about how the point was set or why it is "off". I think there was also some Geologist who weighed in with all kinds of incorrect assumptions. So, if a reporter calls you up and asks some questions you don't know the answer to, it is probably easy to WANT to answer the questions, but it might be smarter to just say "I don't know", or I'll research that and get back to you" or something less harmful. The author implies an attempt was made to get 'answers' from BLM and Utah Geological survey to comment on these questions but didn't get anywhere. It is possible she got a receptionist or a public affairs person and certainly not someone who might have been able to answer. Where she got her original assumptions is still not clear. This is the post: Posted by lynnarave Joined: 16 Apr 2009 Posts: 1 Posted: Thu Apr 16, 2009 12:18 pm Post subject: Media question on 4 Corners -------------------------------------------------------------------------------- Looking at the history of the 4 Corners Monument, it definitely isn’t where it was originally intended to be..... I don’t know if any of you experienced Utah Geocachcers can take a stab at my questions or not----I'm not well versed enough in GPS and have not been successful at getting the Utah Geological Survey or the BLM to answer these same questions---- The exact 4 Corners were supposed to be at an even 37 degrees north latitude and 109 degrees west longitude. However, somehow it ended up at 36 59 56.31532 N and 109 02 42 62019 W. because of survey mistakes. My questions: 1. An on-line calculator figured the difference between the 2 coordinates above at about 2.3 miles apart. Does that appear correct? 2. My next question is if I'm correct in the general direction from the intended 37 north latitude and 109 degrees west longitude spot to the current monument -- it looks to me that the current monument is southwest of the intended location. Does that look correct? 3. So, given if that is correct, it appears that Utah gained some land (all Indian reservation land) out of this mistake, if the monument did indeed move to the southwest. New Mexico too, might have received a sliver extra of land and Arizona was shortchanged the most and Colorado slightly. Does that seem correct? 4. Going from the 37/109 degrees of the original monument goal to the larger numbers above, where the current monument is, that on-line calculator also yielded a bearing of 257.30773862495 degrees and a bearing of 4.4908672298665 in radians, but those numbers are Greek to me. Do they mean anything to Geocachers as far as more absolute directions? This all for a Deseret News "gee whiz" kind of story I would like to do. Any help any forums reader of this can provide would be appreciated and credited for their assistance. Lynn Arave Deseret News 801-237-2168. ----------------------------
  5. The first article that I am aware of on this topic and which may have been the 'seed' was here: Deseret News Without interviewing the reporter it is probably not possible to know precisely 'where' the story came from, but I have the impression that it came from gps hobbiests more of the tourist variety. The question has been raised a few times on geocaching forums over the years. It could also have been raised by people who spend a lot of time on google earth. I guess I differentiate amateur geocachers from the more proficient types and virtually everyone who has ventured into Benchmarking is of the latter variety. The main problem was that the reporting followed disinformation and discounted other input which would have discredited the initial assertions. If I can call up a reporter and make wild assertions that they never really validate with a knowleadgable professional, I think there is great danger in that level of reporting. - jlw
  6. I have been having lots of trouble with posting and editing. Browser times out but post is posted. Edited post but it doubles the post. And neither showing as the latest post. - jlw
  7. The reason I said that the article should not have been published was that there is no such'error' in the location of 4 corners monument. The legally defined corner of the states is actually defined to be at 37 degrees latitude and 32 degrees of longitude west of the WASHINGTON MERIDIAN. The WM was determined from the old Navy Observatory in Washington D.C. which was by another statute that prescribed it for use in the U.S. between the years of 1850 and 1912. It's location was determined later to be at about 77 degrees 03 minutes and a few odd seconds West of Greenwich. Some sources give it a smaller value. So the boundary was not supposed to be at 109 degrees of longitude from Greenwich. Second: That comment made that it had moved once and then moved back is INCORRECT as far as I know. The monument today is a very well documented perpetuation of the original survey monument originally placed there. Some Geocachers have reported another monument to the east that may be a horizontal control mark or a mile marker on the NM-CO Boundary and is not and never has been the state corner. Third: The 'bend' mentioned north on the West line of Colorado is to the West not the East and has nothing to do with an imaginary error at 4 corners. Four: The South Boundary of Colorado has been involved in a number of resurveys all of which used the same 4 corners monument. Some of those surveys were not legally authorized and so a dispute arose between NM and CO which was settled by the Supreme Court in 1928. That case did not involve any change in or dispute relating to 4 corners. Fifth: By law original surveys performed under proper authority are controlling as to location and even though not perfectly performed are considered to be correct. Proper authority for state boundaries are authorization or approval by the Congress of United States, The combined actions of both States approved by U.S. Congress, or the Supreme Court of the United States. The location of all the state boundaries in and around 4 corners are legally authorized and approved boundaries of those states and are considered by law to be unchangeable even though not perfectly located by subsequent technology. Considering the difficulties and equipment available to the original surveyors that established the point, it is remarkably accurate. The only means available in that era were astronomic observations which relied solely on accurate chronometer time and instruments which had to be carried by over treacherous terrain from Durango involved some difficult river crossings. - jlw The surveyors in 1868 thought they were at N38" 00' 00 W109" 00' 00 (dms). Instead, the mark is actually at N36 59 56.31532 W109 02 42.62019, a distance of 2.499 miles. Here is where they should have placed the monument. Also, I agree with jwahl, the article could use a rewrite. I'd be curious to understand how the error occurred, (lack of accurate time, improperly calibrated instruments, accumulated error, etc). ~ Mitch ~
  8. Double post, browser timed out.. Sorry
  9. The article contains erroneous 'information' in almost every thing it says. One could say that it contains considerable error whereas the state lines discussed do not. Really a shame too. I have no idea why this article was even published.
  10. And I have a little 'attitude' issue. In reality a benchmark is a vertical control point. All those evil 'scaled' points are the REAL benchmarks. What this forum and it's users do is recover and help more precisely locate those things which are used to determine the elevation of things that have a major impact on a lot of infrastructure and things like gettin water to run downhill in a pipe that is uphill because someone didn't check into one of these stupid obsolete markers. Finding these things is a service to NGS and society in general. So don't worry about them? To me given a station with an adjusted coordinate, what is the dadgum challenge. That is like shooting ducks in a bathtub. We already know where they are precisely. And much more precisely than YOU can provide any update to. Now it is useful for NGS to know if these still EXIST or if there is a chance they have been disturbed or destroyed. But that info is not as useful as knowing the same about a 'benchmark', and knowing also where it is more precisely which is a function that the people here can provide. So go ahead and shoot all the ducks in your bathtub, but don't try to claim you are a great hunter at the same time. No one discusses this here much but a benchmark is a vertical control point, most often not having a precise horizontal position. The horizontal marks that are "adjusted" are part of the horizontal control network and are not technically benchmarks. You guys have munged the two together, but every once in a while maybe you need to be reminded about the correct definitions. Just because the 'station' is in the benchmarking database does not actually mean it is a benchmark by the traditional surveyor's definition. This would not be an issue with me if someone didn't come up with an attitude about why bother recovering these unadjusted points!! Well sorry they are the actual true benchmarks and the adjusted ones are not. And while it does take some skill and effort to recover 'adjusted marks', they are not benchmarks. Sorry! - jlw
  11. Was it giving you NAD83 or ITRF positions? For California the difference is 1.25 meters more or less which may be a major part of your difference. - jlw
  12. Some google searches seem to indicate that the King's Daughter's home may have been replaced by the Kaimuki Shopping Center which does appear to be close to where you found the disk.
  13. One could check the references to see if it is where it was originally set or has been moved. - jlw
  14. Could it be an unusual outright typo on the data sheet itself. 26.xx seconds versus 36.xx seconds in longitude seems to be the biggest discrepency.. - jlw
  15. There is a guy that has been doing GPS averaging experiments for years people might be interested in. His site is: David Wilson GPS Accuracy Some of the data is pre WAAS, but there are WAAS results also. - jlw
  16. It still doesn't make total sense. It really appears like the same disk in the same setting both before and after the marking. I suppose they could have reset it, repositioned it and then waited 6-10 months before going out and restamping it. A pretty odd one. - jlw
  17. I remember the entire country was covered with control diagrams on a 1:250,000 base map blued out. They showed C&GS control in black and USGS in red and other agency control in a gold yellow. Before the days of internet or even computers, they were extremely useful for planning control projects and I would always acquire one for each project and then order the actual data sheets which were often published by quads from those sheets to cover the areas needed. I am pretty sure they quit publishing those many years ago, but I don't know when, but they may not have been carried forward into NAD83 at all and that is the timeframe of their demise. One thing they did that the internet based tools does not do, is show the network connectivity. In those days of manual paper records a company or county or agency could subscribe to control and you would get mailed any updated data sheets when they became available, and it was not uncommon for people to maintain their own files of all the control in their area or state which would usually include the control diagrams as indexes. I don't specifically remember the state control diagrams but they probably existed too as a general index. And for Bill, the office I worked in between 1980 and 1991 the CA BLM Cadastral Survey in Sacramento, we maintained a full set of the MGS control sheets as well as control diagrams for the state. I doubt they still have them as Gov Bureaucrats are big on moves and throwing seemingly obsolete things away. I have found on several occasions ground marks set directly under occupiable towers or intersection stations such as fire lookouts, bellfries, and so forth. They are usually described thus on the control sheets. If anyone wants examples, I can probably remember a few. - jlw
  18. I would clarify and say that traverse lines ARE definitely connected, as much so as stations in triangulation. However positions are computed by directions and measured distances. The directions being determined from the angles turned AND the distances measured between the stations by EDM or Electronic Distance Measuring equipment. Triangulation you could think of as a way to determine the distances between stations by geometry given only occasionally measured lines. But once EDM technology became available in about that 1960 timeframe distances could be measured directly either with light or microwaves. So now the geometry is a series of points connected more linearly by measured distances. I would expect a C&GS traverse to almost always go from one previously established high order station and close into another. Early EDM's used both light and microwaves and you can probably find pictures of various kinds on the NGS site. Once distance meters became more prevalent, traverse became the preferred and/or economical way to position control points. The first affordable EDMi's came onto the market about 1980. Before that they were more specialized and expensive gadgets to do it. From then on until GPS technology came along in the late 1980's, traverse was how most surveying as well as control surveys were done. One of the last pre-GPS NGS control improvement exercises was the transcontinental traverse which was intented to be very high precision and was included in NAD83. This station is probably not one of those based on the date It is possible that a triangulation station (that is to be completely correct, a station whose position was actually determined by triangulation) may have been monumented with a traverse disk. But by 1960 it is also possible that the station WAS part of a traverse and I suspect that is the case here. Traverse would fit within the definition of 'classic geodetic methods', as opposed to satellite methods. - jlw
  19. I am surprised that NGS didn't evaluate the description before posting it to a datasheet. Surely they must evaluate them. In which case some of the oddball comments can be deleted. The key new information that anyone including a geocacher can provide is an updated location description, condition and for 'unadjusted' marks an updated position. This is valuable to NGS and to surveyors who might want to use the mark. Level benchmarks are notoriously hard to find so this information is valuable. Most NGS database stations are substantial monuments, and recovering them may consist of simple visual sighting to scraping off a few inches of soil or turf that has grown over them. One problem with Cadastral marks is that they are not always so. A surveyor who is trying to retrace section lines within the PLSS township system may at some time be trying to identify very fragmentary evidence of 100-200 year old wood posts or stones. If everyone who comes by starts digging through mounds or digging holes trying to find such remains they are likely to disturb and even destroy such evidence without even realizing it. That is the main caution about Cadastral corners. If the corner is a nice iron post with a brass cap on it, you aren't probably going to hurt anything by recovering it. However, a surveyor may do special things in the way of archeological or biological investigations to verify a corner or blazed and scribed bearing tree, but if a few dozen amateurs come by and start chopping into trees and digging into mounds again the fragile evidence may be destroyed. There are of course surveyors who can be careless as well, but usually fewer of them than there are geocachers and benchmarkers. I feel the same way about amateurs going after underground NGS marks and digging up bottles and other fragile remains. That should be left to surveyors in my opinion, or exercising extreme caution and documenting the work and the position, best leave it alone. That being said, there are many marks destroyed everyday by construction and other oblivious activities so I guess a few more is not necessarily a big deal and there are probably no laws to stop you unless it is the antiquities act. There are many benchmarkers here that set a superior example in terms of research and recovery that would make any surveyor proud. Just be aware of where to draw the line, it is basically common sense, but common sense depends on some level of understanding and appreciation. - jerry wahl
  20. CP2763 plots about 35-40 feet east of the current tower in google earth, based on those buildings that are now underneath the tower. And it is now clearly a 3 legged tower. However discrepancies do appear in descriptions. A good look can be seen in birds eye view from MS live search and compared to a google earth view with the stations coordinates plotted. That is not conclusive because these photos are not always correct or fully corrected. For example terraserver older b/w imagery shows what is probably a 3 legged tower over the buildings at the correct coordinate. - jlw
  21. There are no California survey records on the GLO Records web site at this time. The link I found was to Title plats at the CA office of the BLM. Try this link to the search page: CA MTP Search Page - jlw
  22. It is likely in the Atascadero Grant. There are two basic reasons that there might not be Public Land Surveys in an area. 1) If title to the land was already granted, typically by Spanish or Mexican Grants, but could be Indian Reservations, or lands reserved for other purposes such as military uses. 2) the lands were never surveyed because they were of little agricultural value, such as Death valley or large parts of Nevada. Counties should have tax maps and often have those on line which show the basic title parcels. The BLM has survey plats but they are not currently on line, but their Master Title plats are here: BLM Land Title Plats That you can search by township and Range. I think the area of your coordinates would be T28S R12E MDM and they would usually show what was going on. - jerry I've been looking at an area in California (using GeoCommunicator/LSIS) that is not sectioned. It is T28S R12E Mount Diablo Meridian. 35°27'25.00"N, 120°38'41.00"W is within the area. The USGS topo for this area doesn't have the red township, range or section lines. The Plat that you get from is also not sectioned and is dated current as of Sept 1999. I thought it might be because it was originally a mexican land grant, is there an easy way to find out? What other reasons would there be for it not being sectioned? Where do I start (besides here) to figure this out? I was hoping to find some cadastral marks nearby. Thnx, Bill
  23. What wbf pls is saying is basically what I tried to say in my post of a few days ago. It is more like plate tectonics that are starting to be taken into account in the various geodetic reference systems. There is always a tension between the ability to measure and quantify the actual precise global relationship between points which is now possible with high precision GPS techniques, and having accurate relative positions and stable positions and coordinates of points on the ground. In the old days such as NAD27 the coordinates were tied to lower precision coordinate determination methods and constrained to the derivation of coordinates based solely on terrestrial conventional observations. They never changed. About the time NAD83 was first published, the ability to detect drifts in local areas was starting to be ovservable with GPS measuring technology and was creating problems in defining coordinates that were scientifically accurate over large distances woth the advent of modern GPS technology. We now know that the earth moves at various rates in various parts of the country and globally with respect to other continents. Until recently a station with NAD83 coordinates would remain fixed, but with respect to global reference systems like ITRF it was changing. If you did a GPS Opus session or used the CORS stations to process survey grade GPS you would see reports in the two systems where the ITRF was moving away from the NAD83 values. We now have datum and epoch. That is the datum which represents the reference system ellipsoid and base, and the epoch represents the date that the point or local network coordinate was computed. Most of CORS is NAD83(96) I think. So that means as of the adjustment of 1996. NGS made the decision recently to cut NAD83 loose and let it move with the earth, so there may be future data sheets with newer epochs reported, or surveys with newer epochs reported. The movement is on the order of a few mm's per year but over time adds up to a few feet and depends on where you are. The basic recreational grade GPS unit is NOT usually able to detect these small changes. It's solution would be based on the native almanacs that the satellites transmit and the assumptions about that coded into your receiver. WAAS provides differential corrections based upon stations that were positioned to ITRF coordinates at a certain point in time, and thus those corrections will end up changing the coordinates your receiver computes ever so slightly due to the fact that ITRF coordinates shifted with time based on the plate tectonics shifts as of the date that the WAAS stations were positioned. So if you had the perfect GPS receiver that could accurately compute and report position to 0.01 of a second or better, the WAAS position would differ from the data sheet by a small amount, generally no worse than a few feet off from NAD83 positions as represented by the data sheets. That is about the limit of my comprehension of the subject. It would be very hard to really check your GPS except in the most crude way by sitting on an existent monumented horizontal control point. If you try to do that with say 4 minute averages over several hours or days you will see that although your GPS receiver may report that it is good to 5 feet or so, you will find that your positions actually vary by up to several meters even with WAAS on. In the woods it can be 3 or 4 times worse. WAAS cannot model local conditions and errors which affect your receiver. = jlw
  24. Just as a trivial aside: I think it has been established that the WAAS corrections are actually ITRF values. In some areas of the country those have shifted up to several meters from NAD83(86) published values. Now usually those 1-2 meters are indistinguishable with recreational grade GPS units. You may be able to pick it up with long time averages, AND if you can get a more precise position out of your receiver than is usually displayed. So your WAAS position theortically will not match the published control coordinates. There must be a transformation tool on the NGS site to convert. ITRF positions are time dependent. - jlw
  25. I can give you the exact parameters to set up a Garmin for a SPC Mercator Zone in either meters or feet or Survey feet. I think others have such constants posted on the net also, but I worked out my own many years ago. But it is a radically different proposition to try to shoe horn a Lambert Zone SPC into the user defined system since it is basically setting up a mercator projection. Perhaps it can be done but I am skeptical that it will be very accurate over any significant distance. I fiddled with the idea an afternoon or two and didn't make much headway. It may be possible, but I forget the obstacles that I ran into. After that the problem posed has other issues. The survey data in question if it has local coordinates will likely not be on either an SPC or geodetic basis of bearing. If you assume that is MAY be close to a few degrees and are willing to deal with that then projecting coordinates in one of those standard systems might work. Programs like OziExplorer will also allow you to project a new waypoint Another entire approach is to use some kind of basic COGO to compute the survey coordinates and then apply a coordinate transformation to it based on 2 known points in common between the description and the points on the ground in UTM. We have many programs that would do this kind of thing, but it is not simple to explain all the possibilities in this limited time and space. - jlw
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