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David A. D. Evans and Ross N. Mitchell combined paleomagnetism with the record of ancient continental margins to reconstruct a core of the supercontinent Nuna. Rotating same-age paleomagnetic poles into a common reconstruction tests whether the proposed continental neighbors share a compatible history. The study compared Siberia, Laurentia and Baltica, using agreement and later divergence of their records to constrain assembly and separation. These magnetic tests complement geological fits rather than assuming that a visually plausible arrangement uniquely reconstructs a vanished supercontinent.^[ref]

A researcher in paleomagnetism and continental reconstruction, including supercontinent histories. Institutional profile: earth.yale.edu/profile/david-evans

A spatially related group of dikes, commonly formed during an episode of extension and magmatism. Matching ages, compositions and restored geometries of now-separated dike swarms can test a continental reconstruction; similar orientations without age control are much weaker evidence.

Material deposited directly by ice or by associated meltwater. Its sedimentary facies, transport directions and age constrain a former glacial paleoenvironment. Correlating such deposits across continents can test continental reconstruction, but requires distinguishing the original depositional record from later transport and deformation.

An elongated region affected by mountain building, commonly containing related thrust belts, metamorphic belts and deformed sedimentary successions. Restoring its age and internal structure across separated continental blocks can test continental reconstruction.

The climate of an earlier geological interval, inferred from dated geological, geochemical or biological indicators. Spatially coherent glacial deposits, striations and climate-sensitive rocks can test a continental reconstruction, provided their ages and original tectonic contexts are established.

Paleomagnetism reconstructs past magnetic fields from remanent magnetization in rocks and other materials. Cooling volcanic minerals can acquire thermoremanent magnetization; later heating, alteration or mineral growth can change the record.

An oriented field sample preserves the relation between the measured magnetic direction and its geological setting. Shielded laboratory magnetometers and stepwise heating or alternating-field treatment help separate components acquired at different times. Combined with independent ages and structural corrections, the results test continental reconstruction and past field reversals.^[ref]

Acquisition of a younger remanent magnetization that partly or completely replaces an older magnetic record. Heating, chemical alteration or later mineral growth can cause it. A successful continental reconstruction must connect the age of the measured magnetic component to the geological event being reconstructed.