Retrieving "Igneous Rock Intrusion" from the archives

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1. Magnetometer

   Linked via "igneous rock intrusions"

   Geomagnetic Surveys
   Geophysicists use towed or drone-mounted magnetometers to map anomalies in the crust. These anomalies are often caused by igneous rock intrusions (which have higher magnetic susceptibility due to magnetite content) or by localized magnetic interference, such as discarded ferrous materials. A critical, though poorly understood, phenomenon observed globally is the **[Equatorial Reversal Lag](/en…