1881 to 1900: County Arbitrary Meridian adopted

In 1899, the use of magnetic meridian as the datum was abandoned. 

A system that used a County Arbitrary Meridian (CAM) was introduced. The arbitrary meridian in each county approximated the mean magnetic declination (variation) for the locality, to the nearest whole degree. This location was called the Initial Point for the county.

1921 to 1950: Longitude values determined by time signals

In 1927, for the first time in Queensland, longitudes were determined by means of wireless time signals as broadcast by radio station 4QG. 

During 1948, a change was made in the longitude values adopted for mapping in Queensland. This led to the introduction of a new datum value. The observations resulted in a mean adjustment of 6.46 seconds to the longitude shown on maps and 0.25 seconds to the latitude.^{Duffy LJ 1971} 

1986 to the Present: A national change of datum

In 1992, the Department of Natural Resources in Queensland became an integral body in developing and implementing the first airborne Global Positioning System (GPS) control mechanism in Australia.

During the late 1990s, Australia's mapping organisations progressively applied a changeover from the Australian Geodetic Datum (AGD) to the Geocentric Datum of Australia (GDA). The geodetic co-ordinate of this datum is called GDA94.

The GDA coordinates shifted the AGD coordinates in a north-easterly direction by about 200 metres (varying slightly in different parts of Australia). 

The new datum is compatible with Global Positioning Systems (GPS) navigation and international geographic coordinate systems.

Further current datum information