What are objects placed to mark key survey points on the Earth's surface, also referred to as benchmarks?

What are objects placed to mark key survey points on the Earth's surface, also referred to as benchmarks?

• A. Survey Control Marks
• B. Azimuths
• C. Stream gradients
• D. Elevation

Answer: (A)

In surveying, fixed markers placed on the surface provide known reference points for measurements. These objects are survey control marks, commonly called benchmarks. They carry known coordinates and elevations, letting surveyors reestablish precise positions and elevations for maps, construction, and geodetic work. This network of benchmarks anchors measurements to a common datum so different surveys can be compared over time.

Azimuths are direction angles, not markers; stream gradients describe the slope of a stream, not reference points; elevation is a height value, not the marker itself.