page_title: Cadastral surveying
section_title: Monuments
hierarchical_section_title: Cadastral surveying / Duties and role of a cadastral surveyor / Monuments
caption_attribution_description: Map of Yellowstone National Park
context_page_description: Cadastral surveying is the sub-field of cadastre and surveying that specialises in the establishment and re-establishment of real property boundaries. It is an important component of the legal creation of properties. A cadastral surveyor must apply both the spatial-measurement principles of general surveying and legal principles such as respect of neighboring titles.
context_section_description: Monuments are categorized into two groups which are known as natural and artificial. Natural monuments are things such as trees, large stones, and other substantial, naturally occurring objects that were in place before the survey was made. An artificial monument is anything within the regulations which marks the property boundary—having been placed by landowners, surveyors, engineers, or others. They may be referred to as iron pins or pipes, stakes, trees, concrete monuments, or whatever the surveyor decides to use at the time, within the regulations for the area. The courts have held that natural monuments take precedence over artificial monuments, because they are more certain in identification and less likely to be disturbed.
  Over time, construction and maintenance of roads and many other human acts, along with acts of nature such as earthquakes, movement of water, and tectonic shift can obliterate or damage the monumented locations of land boundaries. The land surveyor is often compelled to consider other evidence such as fence locations, wood lines, monuments on neighboring properties, and people's recollections. This other evidence is known as extrinsic evidence and is a fairly common principle. Extrinsic evidence is defined as evidence outside the writings, in this case evidence outside of the deed. Extrinsic evidence is held to be of equal value to evidence from another source.
  Today's land surveyor sets monuments at actual physical points on the ground that define angle points of boundary lines dividing neighboring land parcels. These monuments are most often ​¹⁄₂ inch or ​⁵⁄₈ inch iron rebar rods or pipes placed at 18 inches minimum depth, but they vary from state by state. The more recent rods or pipes may have an affixed plastic cap over the top bearing the responsible surveyor's name and license number. Older monuments may exist such as old pipes, gun barrels, axles, mounds of stone, whiskey bottles, or even wooden stakes. In addition to rods and pipes, surveyors might use 4 inch × 4 inch concrete posts at the corners of large parcels or anywhere which requires greater stability (e.g. beach sand). They place the posts three feet deep.
  In locations where there is asphalt or concrete, it is common to place nails or aluminum-alloy caps to re-establish boundary corners. Marks are meant to be durable, stable, and as "permanent" as possible. The aim is to provide sufficient marks so that some of them will remain for future re-establishment of boundaries. The material and marking used for monuments placed to mark boundary corners are often subject to state laws. Many states have laws that protect existing monuments and may apply civil penalties if the markers are disturbed or destroyed.
caption: F. V. Hayden's map of Yellowstone National Park, 1871. His surveys were a significant basis for establishing the park in 1872.
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