Bench marks are what?

• A. Permanent brass plates placed in the ground noting feet above sea level
• B. Temporary wooden stakes
• C. A type of map projection
• D. A unit of land measurement

Answer: (A)

Bench marks are fixed reference points used in surveying to establish precise elevations. They are permanent metal markers, usually brass discs or plates embedded in the ground or on structures, stamped with a specific elevation and an identifier. This lets surveyors know the exact height above a datum (often mean sea level or a national vertical datum) so they can calibrate leveling instruments and transfer elevations across locations. Because they’re permanent, bench marks provide stable vertical control for maps, construction, and boundary work. They’re not temporary stakes, not a map projection, and not a unit of land measurement.