What is a benchmark?

A benchmark is a point on the surface of the earth whose position (both location and elevation) is known with a high degree of accuracy. That point is marked in some way, often with a durable metal disk made specifically for that purpose. Each benchmark has a name called its designation, which is usually stamped on the disk. Sometimes the year the benchmark was created or replaced is also stamped on the disk.

More information about benchmarks is available on the Starting Line as well as from the National Geoditic Survey and Groundspeak.