Witness TreeConsultingDennis J. Mouland, PLS

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The witness tree shown was drawn by a gentleman named Ted Drummond. He was a 30 year employee for DOI and drew the current Interior seal (with the buffalo). The tree drawing was first used in a Corner Restoration Circular in 1952, shortly after GLO became BLM. He and others drew some great pictures of survey evidence and restoration processes.

Monthly "How to"

January, 2014 - Road intersections as evidence.


The discussions in the previous two months can also be applied to road intersections. The construction of road on a section line was an obvious intent in many places in the country. The construction itself may have destroyed the evidence. In many places, the grader operator was not really aware of the evidence of those lines, and the position of the road becomes disconnected from the original evidence, whether preserved or not. In practicality, there are many places in the "plains" where little exists but the road. The same questions arise about the relation to other evidence (topo calls, etc.) in the record. It's positional precision is not the sole factor, and it is true that sometimes the road is the best available evidence.

The biggest danger with both road and fence evidence is this: It gets really easy to use it without really looking for other evidence, or supporting evidence. So be sure what really is "available", and then determine the best.

December, 2013 - Fence Corners as evidence - PART TWO.


Use of fences (or other types of occupation) can be even more dangerous inside a section. In most cases, the GLO/BLM never went inside the section. So if a fence was actually based on some sort of corner evidence, it is most likely from a local surveyor. Now the question goes beyond is this where the GLO set it? It is now about whether the surveyor who did it knew what he or she was doing, and whether their procedure was in harmony with the law. Consider these questions:

1. Is there any record of the surveyors work, showing his procedure and evidence used to control his work?


2. If no record exists, is it likely this sort of work was done in the area? Are you in a county where the county surveyor did this sort of work, or other surveyors were conscientious about their work?


3. If all you have is the fence, does it's position relate properly (not perfectly) with the control? Or does one of the 1/4 section corners inverse to be at 2640' from a supposed C1/4 position. These are signs of stubbing, which rarely protects their bona fide rights in the PLSS.

November, 2013 - Fence Corners as evidence - PART ONE.


One of the more dangerous things a surveyor can do is use a fence corner as evidence of a PLSS corner set by the GLO. While it is not impossible, we should consider what it is we are saying about the fence if we make such a decision. First, we are telling the world it is the best available evidence. Are you sure? Have you really researched the record and did your field search properly? Most fences I've seen used were not the best available evidence.....maybe the fastest and cheapest evidence to use, but not the best. When you use a fence corner, what are you claiming?


No better evidence exists The fence corner appears to have been placed with some knowledge of the original corner position The fences themselves are representative of the original lines run Fence construction may have been the reason the evidence is gone.


Think about these four statements and analyze what they really mean. The fences should be running cardinally, with no bows or zig zags. The fact that a proportion hits within a few feet of a fence corner proves nothing either way. Is it in harmony with the other evidence found in the area? (Always short/long, or rotated the same direction and amount). Or is it the place where the ranchers 1320' of wire ended? Does it fit other evidence like topo calls, cultural feature ties, etc.? Is it likely the fence was first built at a time when the original evidence was still present? Why is the evidence gone?


Next month we will expand this discussion to subdivisional corners as well.

October, 2013 - Using topographic calls to reset corners - PART TWO.


A truly lost corner is to be re-established by proportionate measure. The key to this question is whether the corner is really lost, or perhaps obliterated/existent. In other words, is there nearby evidence of sufficient precision to set the corner without resorting to proportioning? In rare cases, a topo call may be a better solution than a proportion. Remember that proportioning assumes the difference between the record and measured is equally distributed along the line between the other evidence. This is not a very true assumption, but one that must be made when math is all we have left to recover a position.


So, if a topo call solution is possibly better than a proportion, it should at least be considered. Here are three real world cases I have seen to help you think about the possibilities.


1. I had a topo call (to the nearest 10 links in the record) for crossing a small stream. The stream was in a well defined little channel, and had clearly not moved. The call was at 1.20 chains from the 1/4 section corner I needed to set. Often topo calls are only in one dimension; that is they identify where a distance was on the line, but not where the line was exactly at the crossing. In this case, I had line blazes (not line trees) along the section line. They varied by about 5 feet for line. I took an average of the line blazes and used the 1.20 chains to set the corner. My option was to proportion another 1.5 miles through very rugged terrain. I felt my position for the 1/4 section corner was within a few feet of the original position at most. A proportion would have had my point fall in the creek.


2. A township corner was apparently lost. It fell on the south edge of a mesa. It had topo calls for the cliff edge in three directions, east, west, and south. All of them were under 50 links. It was clear from the original surveys that it was sitting on a small point projecting south on the mesa. No where else could such a relationship exist. At that point, I found a scattered mound of stones, but nothing with a mark on it. A proportion would place it off the cliff about 50 feet. I chose to use the three topo calls to set the corner and consider it obliterated, not lost.


3. I had a 1/4 section corner to set on a distinct cliff near Gallup, NM. The GLO had run the line and called for the cliff top, with the 1/4 section corner being 40 links back from the top. When I did a single proportion, the corner fell about 20 links out into mid-air. There was clearly no cliff erosion or breaking away. The error in the record/measured distance comparison was probably all in the 300' vertical drop when GLO attempted to measure it horizontally. I used the section corners on each side to control the line, but used the 40 link topo call to fix the point for distance. This preserved the topo call and I believe was successful in "leaving the error where it occurred".


These three stories have some common elements:


1. They were all short distance away topo calls.


2. They were all recorded to the nearest 10 links and were to distinct permanent objects.


3. I verified their reliability with other topo calls by the same surveyor in the same township, feeling he carefully measured and recorded their data.


Bottom line: Be very careful using topo calls. For these three success stories, I have a hundred where the topo calls seemed to be useless. Avoid black and white policies, but always be sure you are truly using the "best available evidence".

Previous Discussions

September, 2013 - Using topographic calls to reset corners - PART ONE.


On most GLO original surveys (and many resurveys) topographic (topo) calls were made, actually measured as the line was being run and noted in the field notes. Basically, a distance along the line was noted and the crossing feature was noted. For example: 40.00 chains is the 1/4 section corner, then at 47.50, begin descent. Occasionally a call would be made to something off the line; these have often been called "passing calls". An example would be: at 49.10, the NE corner of Smiths cabin bears east 2.00 chains.


The question often arises as to whether one can use a topo or passing call to identify a corner point, as opposed to proportioning it. As with everything in the PLSS, there is no simple answer. And as I often warn, don't fall for the "never and always" crowds who prefer a mindless rule over actual evidence analysis.


There are several problems with using topo and passing calls which need to be discussed before considering using them for corner restoration. Their history and process of data collection must be considered prior to use in a resurvey. The idea of topo calls was never really to use them in corner restoration, but rather to aid in plat drafting of certain features, identification of the type of terrain and resources on the land, and a general aid in locating previously set corners. This fact should scare us enough to be very cautious in using them. That does not mean we cannot use them in various ways, but let's ask some important questions about their origin.



Were the topo/passing calls measured well? How do they compare amongst themselves? Do they make sense at all? See slide below right.


What level of precision were they reported at? Nearest chain, or nearest 10 links?


Were the topo/passing calls recorded immediately? Some evidence exists of them not recording these until the end of the line or even the end of the day. The possibility of error in recording otherwise good topo calls is great in this case, and often they will be quite unreliable even amongst themselves.


Was the call something that was at a definitive immoveable point, or a general description? Some can be used more precisely than others...See slide below left.


Is it possible the calls were made on a random or offset line? If so, they are not really approved evidence. See slide below right.


Some of these concerns are self-evident. Obviously a well measured and recorded call made to a definitive feature, to the nearest 10 links, on a true line, is the best scenario. As you change any of those qualifiers, things get less certain. In the best scenario, the closest you will get is plus or minus 5 links (3.3 feet). While that does not sound very precise, it may be far preferable to proportioning the corner in.


Next month we will discuss the application of topo calls in 3 different scenarios to show when they can be used as a superior solution to corner restoration.


August, 2013 - Dealing with a double GLO monument at a corner point.


The GLO had a policy for a time where they would plant a regulation brass cap right next to a stone monument they had found. This unfortunate policy created confusion as to the exact position of the corner point. Was the brass cap added as a "witness" to the stone? If so, were there any guidelines as to where and how far from the corner point this was to be placed? (Similar to Manual guidance on mounds of stones?) Or was the stone moved and the cap marks the actual position? Should we mean the positions? Use the stone since it was the original? Or use the cap since it is newer and marked as if it is the point?


Here is a picture of such a situation, found in New Mexico. Some want to jump to conclusions, such as listed above. But our real desire should not be some poorly thought-out rule, but a solution that fits the circumstances.


1. If there is language in the notes indicating clearly which monument is it, then use that.


2. If the notes are vague or silent (the norm in these cases), then see if there are any accessories (especially close ones) at this or other corners set by the same survey, and see if the position falls on one monument more than the other. In most cases where I could do this, the stone was the place.


3. If there is nothing definitive in the notes, and no accessories are available to check to, some use the cap automatically since the notes say "at the corner point". I prefer to use the stone, unless it is clear they moved it. REMEMBER that their standard method should have been to turn the stone upside down and bury it out of site, placing the brass cap at the correct point. In most of these that I have seen they do not appear to have disturbed the stone at all, and the brass cap seems to have been set as a very close witness.


July, 2013 - Using an off-line Witness Corner.


We understand there are two basic types of witness corners (WC) in the PLSS: Online and offline. This writing is limited to the offline WC. Offline WC's do not represent the line of the survey. Rather, they are simply monumented points to help identify a specific corner from off the line. In this way, they are identical to the purpose of an accessory, bearings trees and bearing objects as an example. In fact, offline WC's are often referred to as artificial bearing trees.


Therefor, to use an offline WC to determine a corner point, we follow the same rules as for any accessory, as is discussed in the January and February entries below. We do not use the offline WC to proportion or modify the record in any way, unless some form of indexing is appropriate.


June, 2013 - Being too picky about GLO evidence.


A good dose of reality and common sense are certainly useful to the modern GLO survey retracer. That original surveyor (or resurveyor in some cases) was not an absolute expert on all things in the world. He also was under tremendous pressure to get the job done as quickly and efficiently as possible. While they were rarely outright dishonest, most of them did an amazing job and we need to be fair and honest about what we "demand" of their work. Some examples follow:


The species of a bearing tree, line tree, or corner tree. - Some of us cannot be too sure of some of these even today, such as a dozen types of oaks, spruce vs. fir trees, and birch vs. aspen.


The exact dimensions of a stone monument - These monuments are reported in inches as the minimum size was expressed in inches. What did they have with them that measured in inches? A link was 7.92 inches, maybe they converted it. But there are good odds they guessed at it and moved on.


The type of rock (geologically speaking) that the stone monument (or a bearing object) is made of.


The description of the soil, topography, or other factors. - These were required at times but were of little interest to the surveyor trying to hustle through a township. Sometimes this data was filled in at the end of the day...not very precise, but met the obligation.


The exact location of the Ordinary High Water Mark (OHWM) for his meanders of a body of water. - He was not required to get the exact sinuosity's of the bank, and often the worst place to do a traverse in the entire township was along that OHWM covered with thick overhanging brush, etc.


Consistency from start to finish. - Reality tells us things were probably not as good at the end of the project as when they began. Running out of time, money, food, or whiskey, could certainly impact the quality of measurements, note keeping, and marking of evidence.


The bottom line: It is not fair or wise to demand perfection of these surveyors or their evidence.

May, 2013 - Honesty with numbers.


Inspite of our incredible abilities to measure and compute, we cannot ignore basic math principles, like rounding and significant figures. Being honest about the numerical data we use is very important. A couple of examples will illustrate this issue:


1. The GLO record calls for a half-mile as 40.00 chains. It was measured to the nearest link, which is 0.66 feet. So the rounding employed is half of that, or 0.33 feet. To say that 40.00 chains equals 2640.00 feet is an incorrect statement. A distance to the nearest hundredth indicates a rounding of .005 feet, a far greater implied precision than the record in chains. This can be an issue when any "argument" is being made over anything less than 0.33 feet in the PLSS. The center of a tree, a record v. measured distance, or the center of a stone monument. In other words, don't argue trivia or math precisions based on units.


2. An old deed you are retracing calls for every bearing to be to the nearest degree. This indicates a precision much less than we can produce today. It opens up a "wider" range of positions that we might find that are still withn the error the record indicates. A 500 feet length with a one degree bearing indicates a half degree of precision, thus implying that anything within 4.36 feet either left or right is still "perfect" to the record. Distances can be done the same way, with many old deeds to the nearest foot or even more. Pay attention to what the record says, and what it does not say.


April, 2013 - Working in the original units when analyzing evidence.


The GLO/BLM surveyors were human and made simple but significant mistakes when establishing corner evidence. Sometimes we have to deal with fraud, but most of the time confusing evidence situations arise due to honest mistakes, like typos, transposed numbers, and wrong quadrants. For this reason, it is best to operate and think in the original units when looking for and analyzing evidence.


If we convert everything from links to feet, we miss the opportunities to identify those honest errors; 27 links instead of 72 links.......it does not work with 17.82' vs. 47.52'. The lesson is to learn to think in the units it was recorded and measured in, and look for these honest errors before giving up on confusing evidence that does not seem to "fit".


March, 2013 - From where do we measure a bearing tree?


Bearing trees were one of the more popular accessories to be tied in the PLSS. There are some misconceptions about how to use them. Other articles in this series have addressed using them in different existent configurations, but from what point do we actually measure the tree?


In forestry, the diameter of a tree is measured at breast height, which is defined as 4.5 feet above the ground. This was done to avoid distortions of the root system in computing the volume of wood in a tree. And while surveyors also measure the diameter there (dbh= diameter breast height), the distance to the tree is not measured to this point. If the tree were to lean significantly over time, the location at dbh or elsewhere on the tree would also change, thus not perpetuating the corner position precisely. For this reason the standard is to measure to the center of the tree at the top of the root crown. This changes little over time, and the center is a repeatable location that low on the tree.


The fact that an "X" was carved at dbh does not change this. Unless specific information is provided that the trees were measured at a different location, the top of the root crown is the only repeatable and precise possibility. It should be noted that in Mineral Claims, the trees were usually measured to the face of the blaze near the top of the root crown, not to the center.


Feb. 2013 - How to determine a corner position when only one accessory remains:


When we find an accessory, it is considered an existent corner, meaning the accessory (bearing tree, bearing object, other fixed object tied in the record) is part of the corner evidence. When only one such piece of evidence remains, the true corner point is determined at record bearing and distance from the accessory. Generally, distance is horizontal from the "X" on the object or the center of the tree at the top of the root crown.


The real issue is that of bearing. Your basis of bearings can make a huge difference in where you place the corner point. A BT 150 feet away could be placed as much as 5 feet off due to a basis of bearings error of 2°. So what exactly is your proper basis of bearings? The PLSS is based on astronomic bearings at every point. Unless you have a very good set of data to index the bearing, it is based on a true astronomic bearing. Rarely do we have good indexing data, so you should seriously consider the astronomic location as the correct and most defensible solution.


Example: The GLO record says a 12" pine bears S23W 120 links dist. You find and validate a now 32" pine as the BT. From the center of the tree at the top of the root crown, measure 79.2 feet at an astronomic bearing of N23E.


Next month: Why we measure BT's from the top of the root crown.

Jan. 2013 - How to use two accessories when the monument is missing or disturbed:


In spite of the name "bearing tree" (or witness tree), the ties to these accessories are primarily based on distances. Hence the term "witness" is better suited, as it witnesses to the existence and position of a corner, even if the monument is not useable. The GLO was required to establish an accessory (trees, bearing objects, other RM type ties) in each section. Thus, a quarter section corner would have two, a section corner would have four.


When 2 accessories exist, the process is to use the distances in the record to establish a distance-distance intersection. Since there will be two solutions, the bearings identify which of the two solutions is the one intended by the evidence.