Editing Public Land Survey System (section)

===Monumentation===

Monumentation is the establishment of permanent on-the-ground objects that mark exact locations of surveyed points and lines. They are the legally binding markers used for setting property lines and as such are the culminating work of any survey. They consist of both corner monuments as well as nearby accessory objects that "witness" to them.  Witness objects allow subsequent surveyors and landowners to find the original corner monument location should the monument be destroyed. It was not uncommon for [[Squatting|squatters]] or [[Homestead Acts|homesteaders]] to destroy corner monuments if they felt the [[Land patent|patenting]] of the land would threaten their residence on it.  For this reason, destruction of corner monuments, or their accompanying witness objects was, and still is, a federal offense.

At corners, ''corner monuments'' are established to mark their exact location on the ground. As with most PLSS specifications, those for corner monumentation also changed over time.  In the 19th century, monuments were commonly a rock pile, a wooden post, or a combination of the two. Trees could be used if the corner happened to fall at the exact spot where one grew. In the 20th century, steel pipes with caps, supported by mounds of rock, became required (for example, see Fig. 4). Witnesses can be trees, rocks, or trenches dug in the ground; their exact locations relative to the corner, and the markings made on them, are also recorded in the surveyor's official [[fieldnotes]].  Witness trees at corners are more commonly referred to as bearing trees because the exact distance and bearing from the corner, to them, was required to be recorded (as well as the [[taxon]] and diameter).

[[File:YoseBoundaryMon.JPG|thumb|200px|right|Figure 4. The cast and stamped cap on a corner monument pipe, in western Yosemite National Park, placed in 1905 during the Park boundary resurvey.]]

On each bearing tree, two blazes were typically required, one about chest height and easily visible, and one at ground level (in case the tree were illegally cut, the stump remaining).  On the exposed wood of the blaze, surveyors were required to inscribe, with wood chisels, township, range and section information, on typically either two or four bearing trees, if they were within some reasonable distance of the corner (unspecified early on but later set at a maximum of 3 chains (178 feet, 60 meters) away). Bearing trees are of vital importance not just for these land boundary purposes but also for their use by ecologists in the estimation of historic forest vegetation conditions before settlement and large scale human disturbance of the land.  The data provided in these surveys provide a definitive estimate of original forest composition and structure, and the data have accordingly been used heavily.

Along survey lines, monumentation was much less elaborate, consisting primarily of only the blazing and some simple scribing of trees directly on, or very close to, the survey line.  The purpose was to help retrace a surveyed line should that become necessary.  It was also additional proof that the line had in fact been run correctly, especially in those cases where the blazed line tree's pertinent information (species, diameter and distance from previous corner) was recorded in the fieldnotes, as was often required.