In surveying, which term denotes a known elevation used as a reference on a plot plan?

• A. Ground level marker
• B. Benchmark
• C. Elevation datum
• D. Contour line

Answer: (B)

A benchmark is a known elevation used as a reference point on a plot plan. In surveying, benchmarks provide vertical control by fixing a precise elevation relative to a national or local datum. This allows all other elevations on the site to be measured and tied back to a single, consistent reference, ensuring accuracy across the plan and construction.

The elevation datum is the standard surface used for measuring elevations (like mean sea level or a national datum). It’s the reference framework, not a specific point on the plan. A contour line represents a line of equal elevation across the terrain, used to illustrate relief rather than serve as a reference for elevations. A ground level marker isn’t a formal surveying term for a fixed reference point with a known elevation.