Remains of Witness Tree near Grand Canyon, AZ
Witness Trees are the more antiquated term for bearing trees. These are specific trees noted and marked by the original General Land Office surveyors as they crossed the country laying out future homestead properties. A Witness Tree aids future surveyors in the accurate positioning of ancient monuments and other evidence of the first survey. They have withstood the test of time by providing survey location data for hundreds of years, in spite of development, mining, forestry, and other improvements made by civilization.
The existence of and measurement data for Witness (or Bearing) Trees is contained in the original field notes of the General Land Office. Although often difficult to read or decipher, they contain important information for the re-establishment of property lines in their original locations.
Modern-day surveyors are required to search for and utilize this data, even if their measurement capabilities are extremely more precise than those used to mark and locate the tree or other evidences. Original Public Lands Survey System (PLSS) monuments and other marks, like these, control land locations in all 30 public domain states. The PLSS was instituted by Congress in 1785 and continues to be the basis for land titles in those states.