There’s a small problem with Earth’s magnetic field: It should not have existed, as Earth’s rock record indicates it has, for the past 3.5 billion years. Motions in the Earth’s molten iron core ...
MINNEAPOLIS / ST. PAUL--There's a small problem with Earth's magnetic field: It should not have existed, as Earth's rock record indicates it has, for the past 3.5 billion years. Motions in the Earth's ...