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Everything posted by jwahl

  1. The historic quad might be interesting: Current Quad BM location Historic Quad SW corner of it Since I see BM's along the RR, I would suspect it was along the railroad parallel and perpendicular. Alternative explanation is along the highway. Very remote possibility would have been cardinal directions. Again level lines would have been run along railroads or highways and BM's established within the ROW's for them. The mark on the quad is about dead on for the intersect, if it 'appears' to be NW of the intersect, that is well within the 6 second scaling error. The symbols were probably plotted using the reported coordinates and so that is not definative. If the RR is torn out to the north as it appears from the photography there is some chance the mark was destroyed depending on what it looks like on the ground. - jlw
  2. The GLO or General Land Office actually was the agency responsible for the surveying of almost all of the original public domain of the United States. That is about everything from Ohio West excepting in large part Kentucky and Tennessee, but including Florida, Alabama, Mississippi, etc. In 1946 the GLO was combined with the U.S. Grazing service and became the Bureau of Land Management in the Department of the Interior (BLM). The remaining survey and records keeping functions are now carried on by that agency. Iron post monuments were used by GLO from about 1908 to their reorganization into the BLM in 1946. That standard form was a 1 inch pipe with a brass cap as shown here, used primarly on 1/4 section corners and other minor corners. Section corners are a 2 inch iron post, and township corners a 3 in. iron post. All concrete filled, and those things are heavy. When the BLM came along, the post was redesigned and is now a 2.5 in. diameter iron pipe with a brass cap. In the last 15 years aluminum, and stainless steel have also been used. However most of that public domain had been surveyed and sold (patented) to individuals or states well before 1908, and so were marked with posts or marked stone monuments. Anything with an iron post has probably been a resurvey of land done for some federal interest, such as US Forest Service, Park Service, etc. but may be found marking lines which are now between private individuals. A resurvey is a re-establishment of the original survey using all the available evidence and record of the previous survey. The description of these surveys is found in documents called field notes, and the parcels involved are shown on survey plats that are kept in the particular juridictions BLM office. Usually on rock, a tablet with about a 3 in. stem would have been set in a drill hole. In this case, perhaps they were out of tablets or didn't have one along with them at the time and decided to use a cut off pipe monument instead. Slightly unusual, but people make do with what they have. Another interesting thing is that this one is 1947, so right after the GLO ceased to exist by that name and they were probably using up stockpiles of GLO monuments. I do not know the exact dates that BLM marked monuments were first used though. Anyway BLM is who I work for. - jerry wahl
  3. While mostly an experience thing, I have two receivers that are pretty much the same except for the antenna. The GPS48 has a vertically rotatable quad-helix. The other is a GSP12CX that has a patch antenna. I find that in any given situation one does better than the other, but can find no real correlation with that and what is happening. For example, in the woods sometimes the 48 does better, sometimes the 12CX does better. They both seem to do about as well or slightly better than the 60C. The GPS76 is supposed to have a helix, but it seems like it must be horizontal and it never seemed to be as sensitive as my older Garmins. - jlw
  4. And of course the GPSMAP60 series do support serial port also, you may have to get another cable for that. Luckily I had some for use with my GPS48 12CX and GPS76. One reason I got the 60C was that it had the old port too. - jlw
  5. A shiner is nothing but a shiny disk, much like a tin can lid attached to a pole or in the ground with a nail in the center. These are often used as surveying references in poles and sometime in asphalt. A breakoff monument is designed to have the top part break off if struck with earth moving equipment, leaving behind a less disturbed subsurface part. Usually bernsten monuments had magnets in them. We should check the catalog and see if that model might still exist to get an idea. Most of the monument is probably aluminum and so that might affect some kinds of metal detectors. Surveying metal detectors work on magnetic fields and so need the magnet or a ferrous monumnet material. Note that some of the NGS data sheets say there is a bar magnet. Here are some modern models: http://www.berntsen.com/products.aspx?c=41 I am pretty sure the model described W-1-B is a different design. - jlw
  6. Angle Point 1 Tract 37, it will be an irregular tract in that township. Tracts can be a lot of things, such as a Rancho, Indian Reservation, or something of that nature, in this case possibly even the National Preserve Boundary itself. Seems like we had one like this just a few months ago. I'll have to search my id and see if it shows up. - jerry PS without knowing the area in detail, it seems more likely to be T14N R18E
  7. Yes a property corner, probably Corner 3 of a U.S. Survey which are usually for tracts of land surveyed in metes and bounds format and done according to the Alaska Native Claims settlement act. If you had lat and long we could probably pin it down a bit more, but not a benchmark in the classic sense. - jlw
  8. This comment is not so much in regard to this particular mark, but something I thought I would point out. There are some of these type questions where considerable more weight for or against a particular piece of evidence could be obtained with a precise GPS position both vertically and horizontally. Thus if you can get a local surveyor interested in the hunt, you might be able to get them to position the point using survey grade GPS. Or level from other nearby marks in the case of a vertical only BM. For example if the mark has adjusted NAD83 coordinates on it, I would expect it to be well within a foot (and usually much less) of that coordinate as recovered by GPS from other nearby monuments of the network. Even on a benchmark, the elevation itself is a valuable tool to aid in recovery or help eliminate possible recoveries or help in determining if it is lost. This again assumes an accurate surveyed in elevation, not one from a typical GPSR If you find the location ground level is 10 feet lower than where you are looking then it is probably not the right place or the ground has been greatly excavated. If you are certain of the horizontal location, it can tell you how deep the BM might be buried today, etc.. There is an old mark listed near me that I would not dream of excavating until I had a good surveyed position in the immediate area so that I can know where exactly to dig, and how deep to look, or if it has likely been destroyed since it cannot be 6 feet above the current ground. Just some thoughts. -jerry
  9. As to the standard tape. The official way is to send the tape (usually survey type) to NIST and for a particular fee they will give you a calibration report and certification. Some survey supply houses may also be able to do it. For example: Warren-Knight NIST Calibrations - jlw
  10. My first guess is that they may be marking a true meridian. Many county and state governments had a practice in the 1800's of setting two points on a true meridian in local areas for the use of surveyors to set their magnetic surveying compass by. The meridian would have been determined by fairly simple astronomic methods such as polaris observations. Then any surveyor can come by with his compass, set it up on the south mark, sight the north mark and adjust his declination so that the compass indicates north. This would allow all surveys in the general area to be on the same basis of bearing and be very close to being on the true meridian. There are still many statutes on the books requiring these to be established locally in several eastern states. I have not researched this set of marks to know if this is a possibility. If they do truly fall exactly north and south of each other and without any other knowledge the possibility seems high. - jerry PS I found a specific reference to what are probably these marks in the online archives of the Maryland Geological Society, Volume 1, 1897. MARYLAND GEOLOGICAL SURVEY 509 The purposes of such lines are: (a) To enable the surveyor to readily determine himself at any time the declination or the " variation of the compass " at the county- seat and thus to provide the means for determining the amount of secular change. ( To furnish a common line whose magnetic bearing as well as its true one has been accurately determined, on which surveyors can from time to time test and compare their compasses. If such lines had been established long ago at the various county- seats the re-running of old lines would have been greatly simplified; for in addition to the secular change being now accurately determin- able, the condition of the compass used in the early survey would have been known. The law provides, namely, that every surveyor shall duly file with the county clerk the " amount of variation " or magnetic bearing given by his instrument on the authoritatively established county meridian. It is well known that compasses may differ greatly from each other by reason of the fact that the proper care is not, in general, bestowed on them. A magnetic needle poised on a fine pivot point is a delicate instrument and must be carefully handled if it is to settle in the right place when it comes to rest. Nine counties have thus far availed themselves of the privilege of having their meridian lines established in connection with the mag- netic survey. These counties are: Baltimore, Dorchester, Charles, Frederick, Harford, Kent, Queen Anne's, Talbot and Wicomico. The method used in the establishment of the lines was that of altazimuth observations on the sun before and after noon. When for some reason, which only occurred once, observations could not be made on both sides of noon, then special observations for a suffi- ciently accurate determination of the latitude were made. The accu- racy aimed at was, that the established line should be correct within one minute of are. The instruments employed were those used in the magnetic survey. The line was permanently marked by two granite monuments about four feet long and seven by seven inches square. The monuments were generally imbedded in several courses of concrete and were allowed to project about 5 inches above the surface. In the centre of each was leaded, flush with the top, a brass dowel one inch in diameter and three inches long. The line was marked by crosses cut in the brass dowels. The tops of the monuments contained some suitable lettering, as for example: North Monument or Meridian, 1807. Owing to the lay and character of the grounds about the court- houses1 it was not always possible to plant the monuments on a true north and south line. Of course any line whose true bearing is known will suffice for the surveyor's purpose. It was my endeavor, however, always to select as simple a line as possible. Thus at Fred- erick (Frederick), Salisbury (Wicomico), Towson (Baltimore) and La Plata (Charles) north and south lines were given; at Bel Air (Har- ford) and Chestertown (Kent), northeast and southwest lines; at Cam- bridge (Dorchester), a northwest and southeast line; at Centreville (Queen Anne's), an east-southeast and west-northwest line, and at Easton (Talbot), an east and west line. After the line was established careful determinations of the mag- netic declination, or variation of the compass, were made by me over the monuments with the Coast and Geodetic Survey magnetometer. The surveyor, hence, in addition to obtaining a line whose true bear- ing was known, also had the privilege of having determined for him the magnetic bearing with an instrument especially adapted for the purpose. This accurate magnetic bearing gave him the means of determining the reliability of his own instrument and of obtaining the correction to be applied. When the conditions were such that it was not possible to get 1 The law prescribes that the line shall be established on some public lot adjacent to the Court House. entirely beyond the disturbing influence of some artificial cause near the place where by law the line had to be established, special mag- netic observations were made at some point near the town where there was no reason to suspect a local disturbance and the result of these observations likewise furnished to the county commissioners. The Frederick and Wicomico lines were established in the fall of 1896 and the remainder in the spring of the present year. More detailed reports of each line have been prepared and sent to the respective county commissioners and will, doubtless, be published in some other connection. Numerous inquiries have been received by the Maryland Geological Survey with regard to simple methods for the determination of true meridian lines—such methods as could be employed with the average instrumental equipment of the surveyor. In the hope that the furnishing of this information to the surveyor will be instrumental in inducing him to determine the magnetic de- clination or " variation of the compass " more frequently than is his- custom, I take pleasure in complying with the requests for this infor- mation .and have accordingly added the following article. The method used in the magnetic survey—that of determining the true bearing of some distant mark by solar observations—while more expeditious for the work of the survey is not one that the surveyor in general can employ with success. I have therefore omitted an explanation of this method. The extensive article goes on to describe in technical detail how to determine true meridian using polaris and is a common method from the 18th and 19th centuries to do so. The whole article How do you like that? jlw
  11. Each point will likely have the same lat long, but they represent different points vertically. The mon is the monument itself. Remember these have a GPS antenna permanently set on them, and there are a number of vertical values assigned from GPS antennas'. A surveyor who is using a CORS station has collected GPS data using their own receiver at some point, then download the data from the CORS receiver and processes them to determine a position. To get an accurate vertical the post processing software must know how 'high' the CORS station GPS antenna is. To this end the "ARP" or antenna reference point is one method used. The surveyor must then look up the specs for the specific antenna and get the elevation difference between the ARP and the electrical center of the antenna. Another measure is called the L1 phase center, which is an average of the electrical center of the antenna for the L1 frequency used for static GPS survey work. There may also be an L2 phase center, and variations of these. The L1 value is commonly published. So usually there will be the mark, above it somewhere the ARP and some small distance above that the L1 phase center. There must be some good pics on the NGS cors web page to illustrate this, if anyone is curious I could hunt some down and post them. There are pics of many CORS stations out there. - jlw
  12. My opinion is that the map shown in the original post is a rough schematic only and based on a perfect township as to the section lines, and very crude determination of roads. If you look at the roads shown, they could never have been where shown. This is typical of mid 1800's era atlases which are composities of the land ownership and very rough wheelbarrow type surveys of the roads and habitations. Thus overlaying that onto the current quad or ortho isn;t necessarily meaningful. Base on my experience, but not a dead cinch, there are sufficient occupation lines shown to believe that the N and S centerline of the section and its relationship to the section lines and all of it adding up together places the likely position at longitude I gave earlier in line with edge of field and probably a fenceline to the south. Also the N-S position may be indicated by remnants of a fence to the west of where the road curves off to the south. Occupation lines fairly easily locate the North 1/4 corner of the section and the South 1/4 section corner which define the N-S centerline. There is nothing that obvious between then defining the E-W centerline or the corner we are trying to find. These can at best come from apparent fragments of occupation lines in relation to proper distance location.. - jlw
  13. Similar to last, the Center South 1/16 cor of that section is probably near: 36-37-47.7 but could be 30 or so feet north, I picked point in the road 93-48-12.56 in line with edge of field and possible fence to the south NAD83 - jlw
  14. Yes, probably a boundary AP4 meaning angle point number 4 (metes and bounds survey) TR101-102 a little odd, but possibly Tract 101 and 102 or between them. REC SMM NRA Guessing NRA is National Resource Area so abbrev for where you were Santa Monica Mountains NRA It was set in 1995, so I could probably track down the record if someone was desperate for it call CA BLM Cadastral Survey. - jerry wahl
  15. Well I did a computation assuming I knew nothing else than what was provided. I then offered a discussion of what I do know beyond that. The only thing I did not do was follow through the true location as found on maps for comparison, you can do that and judge for yourself. I saw no feedback or interaction about the issue after my posts until now. So I guess I am not sure what the question is. If it was not as stated an abstract computation of where a township 'should be' we can go more into that. Or is it now why is the PLSS so bad? Well it was done in the wilderness on the frontier and in a way that was reasonable for the time in line with a number of acts of congress to get the public domain surveyed platted and sold both as support for the Centerl U.S. Government, and to allow for the expansion of the country providing for any citizen to buy and possess land in an agrarian age. Topo maps didn't exist, the GLO plats were the first maps of most of the country. NGS or CGS control didn't exist either except in a few coastal areas. The PLSS is pretty good overall. It's goal was to get the land surveyed, monumented, described and sold. In 1805 an act was passed which provided that the corners and lines as actually marked on the ground represented those line. This was done to allow stability based on the work done on the ground versus a mathematical abstraction. The initial point NOW has control on it, from what date? (not 1820) A legal description BASED on the PLSS is referenced to the initial point by way of description, but not mathematically or geographically. The land is fixed on the ground by the actual survey done for that township. The initial point is no more critical than saying what state it is in, or what county it is in as to it's position on the ground is only roughly informative. The PLSS was based on the true meridian and is not in ANY way a plane coordinate system, or even a coordinate system at all. E-W lines are curved parallels of latitude, and N-S lines are converging meridians. As the system was developed past the first surveys in Ohio the problem with convergency was beginning to be recognized and so a system was developed to deal with it. As the townships and ranges were laid out and approved by the GLO the monuments established in them control over any idea of where they 'should have been'. Second, the very nature of surveying with relatively crude tools, for not too much money, under adverse conditions, and in a relative hurry lead to error, and in some cases blunders. The PLSS was extended in a non uniform way from the initial points entering different areas from different directions. Without extensive specific research on the actual order and progression of surveys in AR from the initial point it would be difficult to speculate on why the errors are where they are. Such work might require many months of work after months of collection all the records and then laying them out in chronological order and comparing each with where they are found today on the ground, followed by speculation as to why a particular error may have occurred. Often it can only be guessed. One explanation is that the stuff on each side of the rivers were extended for many miles independently on each side. Another factor was that indian title had to be extinguished before surveys could proceed and lands offered for sale. There are a number of these old indian lines that cross Arkansas. There are GLO maps out of old GLO reports on some of the map web sites that can provide some insight. If anyone is interested I could hunt down some links. I would first try the Library of Congress map library, and then the David Rumsey Collection http://www.davidrumsey.com/ search by state for Arkansas and there is a GLO map from 1866, the PLSS is already in, but the offsets are shown, so they knew they had them. The earliest atlas map there which appears to be derived from GLO work is 1840's with similar data. So that doesn't help. We may need to go back earlier which gets hard to do. There are some maps on the library of congress site which so some of the PLSS incomplete along the rivers Burr Atlas 1839 for example. Lots of interesting stuff though. I thought about using the comps in Ozi explorer or in my Garmin instead, but had a program on the PC at hand. - jerry PS, often language on monuments or in books or on web sites make some kind of point about all the lands in such and such an area are based on this point. This slightly over emphasizes and may mislead one a little as to the importance of the initial point. The surveys progressed from them, and are numbered from them, but once the surveys were marked on the ground the initial point has no more signficance than that historical thing. If you lost the initial point monument (some have been), no ones property is affected or influenced in the slightest.
  16. After uncovering several errors including a wrong value for the IP, I now follow on the map. M1 TopoZone M1 by map 36-25-08 / 91-01-14 I think that is the right township corner. It is sometimes hard to tell when looking at topozone maps as the Tp and Rg numbers are usually on the map collars which we don't see. Okay so now on west to W1 Well if you look at the maps, it is a real mess as the PLSS crosses a few rivers there are offsets of several miles. At this point the exercise becomes futile. - jerry
  17. So here goes. A more accurate current NAD83 position for the initial point of the 5th PM is: NAD83: 34-38-44.5 / 91-03-07.3 Assume 4 township blocks and therefor step 1) Guess the arkansas windage without a map? Or ignore it. 1)We are going to T22N, therefor the standard parallel south of that will be the north line of T20N (5*4) we go 20 x 6 miles or 120 miles north from the IP 2)We need to go to the SE corner of R27W or 26 township west along the standard parallel, that might work out 26 x 6 miles at that latitude. 3) Now we can go north 12 miles to the SE corner of that township within that block. Again that assumes that the blocks are in fact 4x4, which they are not many places. Bearings would be assumed to be geodetic except we know that will be off due to the Arkansas windage, but we can see how far off it is. I will use a geodetic traverse program of my own but you could use the interactive stuff on the NGS sight for the N-S part. Elevation would theoretically affect the ideal computation because the lines were run and measured at ground elevation, not ellipsoid. However most of this will be in the mississippi basin and so assume the affect is negligible. For 1 assuming no windage and average elevation of 200 feet I get M1 36-23-10.7 / 91-03-07.3 For 2, to go west is hard to do on the NGS program because if you start out with a forward bearing of west you will head more and more southwest as you go west and not be west. To follow the standard parallel the line will actually curve to the right looking west. My program figures this out so I am cheating a bit. Forward bearing to get there is 270d49'48.4" W1 36-23-10.7 / 93-51-01.1 For 3, we go north again 12 miles if I had figured it right. SE 36-33-37.2 / 93-51-01.0 Expressing way more places of accuracy than is justified. Now we go to the maps and see what went wrong with all my assumptions. 1) are the blocks of townships 4 miles N-S? 2) what is the windage and how far does it extend north? 3) etc. Early work like this may not have dealt with the convergency in the way that evolved slightly later. Now I made some mistakes and just edited this. Lets look at the map and see how far off it is. - jlw
  18. As others have said, one can do the math for exercise and then see how far off you are. The PLSS is not that orderly that you can reliably project that far from the initial point. Since convergencey was built into the corrections at intervals with standard parallels and guide meridians that pattern or interval would affect where you can go 6 miles and where it is short. For example, you are more likely in a theoretical sense to get to the right location by going north on the meridian (if it is even run all the way, not all are), and then east or west along the first standard parallel south of the township, Since those have full 6 mile measure, then north. To know for sure where they are may in fact depend on either looking at a map, or knowing what the instructions were to the surveyors laying it out, as suggested by someone. Also note that the Lat /Longs of the initial points in the Manual are rough in some cases and in NAD27, not that the diff there won't be washed out by accumulated errors in the PLSS going that far anyway. For example, the initial point for the 5th is in AR and if you will notice most of the PLSS lines in AR up to southern MO have a fairly consistent bearing bias (often referred to as the Arkansas Windage), so right away you need to know what that is or drift off considerably to the east as you travel north. Townships are not generally square even in the ideal, the east and west sides run north (converging meridians) through the 4 township blocks. In some areas the blocks are larger than 4 townships. I will come back and work it through to show the basic process i would follow. standard parallels are 4 townships apart. - jerry
  19. Monumented AP's which stands for Angle Point are seldom on section lines, but on other metes and bounds parcels such as Indian Reservations, Grants, and other claims or tracts of land that do not conform to the regular PLSS. In this case there is a tract of land going up and down the creek that is Navajo Trust lands for some reason. While such monuments are not principally bench marks, technically neither are a lot of NGS horizontal trig stations. This forum seems to have always allowed a certain degree of diversity and curiosity when it comes to unusual survey marks out there. The description of BLM survey marks is usually contained in official field notes and can be obtained from your BLM state office. - jerry wahl
  20. Back to one original question. Azimuth marks seldom have distances to them. If I go that azimuth forward geodetic about a half mile and then back up the line to the east side of the road, I get a coordinate of about 33-50-50.1 / 117-38-53.2. Of course judgement about where it is in relation to the road, possible road widening, grading, etc. , may affect that. The 0.55 miles would be road distance. Also, so you should be able to clock down from the station with odometer and be within a few hundred feet. If no vehicles are involved you could build a route and check it. I am looking at photos from terraserver using usaphotomaps. doing that I come out very close to the same point, i.e. 33-50-50.4 / 117-38-53.2 Again guessing a distance beside the road maybe 30 feet from center or so. Look there. - jerry
  21. Metric system was made legal in the U.S. in 1866 (not mandatory, but legal to use), there was a rush to try to metrify the U.S. starting in 1975 (Metric Conversion Act of 1975 (Public Law 94-168) and at about the peak of that activity was 1991-95 (Executive Order 12770, Metric Usage in Federal Government Programs). about the time that this plaque was placed. However I think NGS and C&GS may have darn near always used meter, but would have to do some digging to verify. - jlw
  22. Well first off, if in fact the survey was related to astronomic observations the bearing in that area will be virtually identical to GPS or 'geodetic' bearings. This is not to be confused with UTM grid bearings. Geodetic bearings between points can be confusing. But at a given point an astronomic bearing and a geodetic bearing are very very close. The difference is related to the deflection of gravity from normal to the modeled ellipsoid at that point. Generally this is well under 8 seconds with rare exceptions. - jlw
  23. My first guess, a cover to an electrical outlet or light fixture?
  24. Another explanation is that someone has at sometime in the past placed an aerial survey target on the station and used rocks to hold down the material. I have placed many such panels myself. Ours consisted of plastic sheets, 18 in wide and each arm of the + was 15 feet long. After the panel material had decayed only the rocks used to hold it down might remain. There may be other features in the area that corroborate or diminish that guess, but it is the first thing I thought of particularly since it is oriented towards the mark in the photo. - jlw
  25. To answer one question, RM's and azimuth marks are not necessarily required. Anyway I was tempted once to try to use a point on a peak to the North of Kings Canyon for some work a crew was doing in that area. It had a similar go to description. I think it was GT1860 Tri Station "Spanish", of course I didn't venture that hike. One I did search for in the deep dark woods, that would be much easier to find with GPS is in Northern Washington and used for the survey of the International Boundary: TR0980 Sumas This one was in deep dark timber and vegetation when I was there. We did not look for this one. TR2662 Sumas Mountain. Okay, it's easy to come up with hard ones to find from the armchair...
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