Definition: A surveyed location that surveyors or cartographers use to confirm elevation. Benchmarks are usually metal disks set into concrete or rock in the ground. They are placed by national surveying or mapping organizations, such as the United States Geological Survey, and indicate the elevation at the benchmark. Topographic maps indicate the location and elevation of benchmarks.
Examples:
I discovered a bronze benchmark in the field near my house; its elevation is 52 feet above sea level.
