Blog · September 30, 2026
What Is a Reference Monument?
A reference monument is a durable mark set near a corner and tied to it by a bearing and distance. It helps the next surveyor rebuild the corner if the corner mark is gone. It is not itself the corner of the parcel.
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An accessory, not the corner
When a corner is likely to be disturbed, a surveyor may set one or more reference monuments nearby and record how far, and on what bearing, each one sits from the corner. Highway work, bank erosion, and new pavement all swallow corner marks. The reference monument is placed where it has a better chance of surviving. On the plat it may be labeled RM, with a distance and a direction back to the corner. Two references can fix the corner by intersection even if the corner monument itself is missing. One reference fixes a direction and a distance, which still has to be read, not paced off with a phone.
Where you will see the tie
Look in the corner detail, the legend, or a short table of accessories. The tie might read something like an iron rod with cap, 45.00 feet north of the section corner. That sentence does not give you 45 extra feet of yard. It tells a later crew how to measure from a surviving mark back to the corner position. If several reference monuments are listed, write each tie on a separate line. Mixing the distance from one mark with the bearing from another will invent a point the survey never set.
How this differs from a tax-map dot
The county parcel viewer is an assessment map. It is not a survey, not a recorded plat, and not a substitute for the deed or for a licensed surveyor. It will not list reference monuments. Platbookmapper links to the county GIS page for the parcel and stops there. It does not trace accessories, and it does not turn a screenshot into a stakeout. If you need the corner occupied, hire a surveyor. Do not cross a neighbor’s land to hunt for a disk, and do not move a fence because a website dot sits near a reference mark.
What to do next
- Read every RM label and copy each bearing and distance.
- Note what object was set, such as a pipe, a disk, or a rod and cap.
- Sketch the references as ties to the corner, not as extra corners.
- Hand the recorded ties to a surveyor if the corner itself must be reset.
The mix-up to avoid
The usual mistake is to fence to the reference disk because it is the mark someone can find. The disk was set off the corner so it would survive. The corner is at the end of the tie.
Questions people ask
How many reference monuments does a corner need?
There is no single count on every plat. One well-described reference can be enough to recover a corner along a known line. Two references can reestablish a point by intersection. Read how many the notes actually call, and do not assume a second disk exists because a textbook diagram showed two.
Will a metal detector prove I found the reference monument?
A beep only says metal is nearby. It does not identify which rod is the reference, and it does not measure the recorded tie. A phone, a measuring wheel, or a laser measure can help you look. None of them is a survey.
Find the county map
Open Platbookmapper and pick the county that taxes the land. Use that viewer to get the parcel id, then match it to the recorded plat if you need the easements and lot numbers.
Not a survey. County GIS and tax parcel maps are assessment and planning layers. They are not a substitute for a recorded plat, deed, or licensed survey.