Paleomagnetism in some volcanic areas where scientists have determined the yearly changes in the position of the Earth's magnetic pole over the past several hundreds or thousands of years and when the Earth's magnetic direction is preserved in volcanic rocks (usually lava flows and individual large rocks in pyroclastic flows);
(scientists; have determined; the yearly changes in the position of the Earth's magnetic pole; L:some volcanic areas) (the Earth's magnetic direction; is preserved; L:in volcanic rocks) (lava; flows; T:usually)
scientists the Earth's magnetic direction lava
have determined is preserved flows
the yearly changes in the position of the Earth's magnetic pole L:some volcanic areas
L:in volcanic rocks
T:usually