101. Magnetometers (1968)


Local differences in the values of Earth’s magnetic field reflect the properties of the underlying bedrock. To make use of this, airborne magnetic surveys in Canada were started by the Geological Survey of Canada in 1947. In the 1960s, however, a new generation of magnetometers sparked a global revolution in airborne magnetic mapping.

In Canada, Dominion Observatory scientist Paul Serson working with Survey geophysicist Larry Morley adapted a Proton Precession magnetometer to record the magnetic total field more accurately than previous systems. With magnetometers towed behind aircraft flown at elevations of 1000 feet, the Survey embarked on a campaign of surveys to supplement geological mapping and to stimulate mineral exploration.

The Proton Precession magnetometer was superseded by the Rubidium Optical Absorption magnetometer – first used in 1968, mounted behind the Survey’s Queenair aircraft in a boom system. With sensitivity one hundred times greater than the Proton Precession, the Rubidium enabled a more precise determination of geological sources.

In turn, the Rubidium was superseded by Cesium-Vapour Split Beam magnetometers with sensitivities more than a thousand times that of the Proton Precession. This improvement, coupled with GPS positioning, now produces very high-resolution aeromagnetic survey data.

Category: Equipment and Instrumentation

Decade: 1960s

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