What is the term for a permanent reference point established by federal government agencies for surveying purposes?

The term "permanent benchmark" refers to a fixed reference point established by federal government agencies to provide accurate elevation data for surveying. These benchmarks are formulated using precise measurements and are often marked with a metal plaque or disk, ensuring that they remain unchanged over time. They serve as a vital resource for surveyors, engineers, and planners as they offer a consistent and reliable reference for elevation and horizontal control, essential for map-making, construction, and various engineering applications.

While the other choices represent different types of reference points used in surveying, they do not specifically capture the definition as completely as "permanent benchmark." Reference markers may refer more generally to various types of markers used on construction sites, whereas a survey point could denote any point used in surveying without the implication of permanence. Control points might be short-term or involve different methods of establishing position, but they may not be specifically tied to elevation like benchmarks. Therefore, the identification of a permanent benchmark is crucial when discussing stable and reliable reference points in surveying contexts.