Scientists have uncovered a huge magnetic anomaly beneath Australia's Northern Territory, with the formation bearing a striking resemblance to the country's outline.
The discovery, made through sophisticated modelling methods, has been dubbed the Australia Magnetic Anomaly.
And the underground feature contains crucial details about the continent's geological past.
The anomaly provides insights into how various rock layers came into existence and developed their unique magnetic characteristics.
Researchers from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) led the project examining this hidden geological structure.
Their mapping work exposed features that conventional surveying approaches had previously failed to identify.
Magnetic anomalies occur in Earth's magnetic field when minerals and rocks with magnetic properties are arranged in a certain way.
Rocks begin acquiring magnetic signatures from the moment of their formation.
Researchers were shocked to discover an Australia-shaped object hiding beneath the Northern Territory
|CSIRO
These signatures capture information about the direction of Earth's magnetic field at that particular point in time.
Scientists refer to this phenomenon as remanent magnetism, which functions as a kind of magnetic memory.
This preserved record enables researchers to piece together what rocks experienced throughout their history.
By deciphering the clues inside a rock's magnetic signature, geologists can reconstruct the precise events and timing of geological processes.
"Magnetic data allows us to see through the ground and understand geological architecture that would otherwise remain completely hidden," said Dr Clive Foss, senior research geoscientist with CSIRO and project lead.
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Scientists used magnetic analysis to shed light on 'invisible' underground formations
|CSIRO
Dr Foss and his team employed advanced modelling techniques to better visualise magnetic data.
The original magnetic information was gathered during a survey conducted by the Northern Territory Government in 1999.
The Australia Magnetic Anomaly has revealed structures including faults, folds and basins, which traditional mapping methods had been unable to detect.
The research demonstrates how magnetic analysis can shed light on "invisible" underground formations.
The Australia Magnetic Anomaly has revealed structures including faults, folds and basins below the country's vast red deserts
|NASA
Interpreting these magnetic signatures presents significant challenges for researchers.
Earth's magnetic field periodically flips, complicating the analysis of rock formations.
Such a challenge arose to researchers looking into ancient humans in a 700,000-year-old cave in Morocco.
Tectonic activity can also shift the orientation of rocks over time, further muddling the geological record.
But, when researchers successfully decode the various signals encrypted within a rock's magnetic properties, they can determine precisely what occurred and when.