LSIT Geodesy and Control Surveys

Question 1

The geoid is best described as:

Accepted Answer

An equipotential surface of Earth's gravity field approximating mean sea level

Answer

The geoid is an equipotential surface of Earth's gravity field that closely approximates mean sea level globally.

Question 2

The difference between ellipsoidal height (h) and orthometric height (H) is called:

Accepted Answer

Geoid undulation (N)

Answer

Geoid undulation (N) is the signed vertical distance between the ellipsoid and the geoid at a given point, expressed as h = H + N.

Question 3

NAD 83 is based on which reference ellipsoid?

Accepted Answer

GRS80

Answer

NAD83 uses the GRS80 (Geodetic Reference System 1980) ellipsoid, while NAD27 was based on the Clarke 1866 ellipsoid.

Question 4

Which vertical datum is the official vertical datum for the contiguous United States?

Accepted Answer

NAVD 88

Answer

NAVD 88 (North American Vertical Datum of 1988) replaced NGVD29 as the official vertical datum for the contiguous United States.

Question 5

A benchmark is best defined as:

Accepted Answer

A permanent marked point with a known elevation referenced to a vertical datum

Answer

A benchmark is a permanent, stable monument with a known elevation referenced to a vertical datum such as NAVD 88.

(LSIT) Land Surveyor in Training Practice Test