Geoscience Reference
In-Depth Information
Some kinds of sedimentary and volcanic rocks contain minute
particles made of iron-bearing minerals, such as magnetite. When
these particles settle out through a water column or cool within a
body of magma, they align themselves with the earth's existing mag-
netic field. So, in rocks, these microscopic, magnetic mineral grains
reflect the direction of the magnetic field at the time that the rocks
were formed, which we can then analyze in a magnetometer.
Magnetic polarity indicated by the rocks exposed
at Auca Mahuevo.
