Survey marker

Closeup of a United States Coast and Geodetic Survey marker.
United States Army Corps of Engineers Survey Marker
Bronze disc set in concrete
Marker for triangulation station, indicated by triangle in center
Bronze disc with inscribed arrow, set in concrete
Reference marker for triangulation station in upper photo
A cotton spindle spike in Tel Aviv pavement, used as a marker for public area cadastral surveying.

Survey markers, also called survey marks, survey monuments, or geodetic marks, are objects placed to mark key survey points on the Earth's surface. They are used in geodetic and land surveying. A benchmark is a type of survey marker that indicates elevation (vertical position). Horizontal position markers used for triangulation are also known as triangulation stations. Benchmarking is the hobby of "hunting" for these marks.