The magnetism left in rocks is a record of the magnetic field when the rock solidified.

Dance music trends developed every few months, formerly obscure world-music artists collaborated with pop stars, and alternative rock solidified its position as the new Top 40.

Then close the insulation ports and wait while the molten rock solidified over the next century.

These rocks solidified 414 9 Mya.

The rock abruptly solidified and Zedd stepped atop it, into the light.

However, argon, being a gas, is at zero concentration when the rock solidifies from the molten state, so the amount of argon produced is measured.

The hills were formed in the early Paleogene period, and geologically are known as stocks - intrusive igneous rock forced up from below and solidified.

Radiometric age determinations of the minette establish that these volcanic rocks solidified about 27 million years ago.

New oceanic crust is being formed by hot molten rock slowly cooling and solidifying.

When such rock solidifies, the magnetite aligns itself with the prevailing magnetic field at the time, thus providing a sort of "fossil" magnetic record.