The National Geodetic Vertical Datum of 1929 refers to a sea level baseline measured in which year?

The National Geodetic Vertical Datum of 1929 refers to a sea level baseline measured in which year?

• A. 1929
• B. 1900
• C. 1950
• D. 1980

Answer: (A)

Vertical datums fix elevations to a single reference surface, defined by mean sea level at a specific time. The NGVD 1929 is tied to mean sea level as it existed around 1929, determined from observations at many tide stations and a nationwide leveling network. That year is part of the datum’s name, indicating when the reference surface was established. So the sea level baseline is defined for the year 1929.

Vertical datums fix elevations to a single reference surface, defined by mean sea level at a specific time. The NGVD 1929 is tied to mean sea level as it existed around 1929, determined from observations at many tide stations and a nationwide leveling network. That year is part of the datum’s name, indicating when the reference surface was established. So the sea level baseline is defined for the year 1929.