Rock Magnetism

location, usually as the mineral hematite. As the iron minerals form they acquire a magnetic remanence parallel to the Earth's magnetic field at the time they form. Most times CRM could have been acquired at any time, so it often has little to do with the magnetic field when the rock was formed. It is important to understand and identify magnetic properties formed by CRM so their results to not interfere with the research into the true magnetic field of the rock.

Magnetostratigraphy has become a powerful tool for the geologist hoping to correlate widespread and differing types of rocks. Understanding how magnetic minerals align themselves with the Earth's magnetic field allows geologists to construct a magnetic time scale based on normal and reversed polarity and, as we'll see in a later article, played a key role in promoting the theory of plate tectonics.

My next article will cover how geologists sample and measure rocks for their polarity and how rocks can be demagnetized to reveal their true magnetic properties.

References:
Seyfert, Carl and Sirkin, Leslie; Earth History and Plate Tectonics: an Introduction to Historical Geology; 1973, Harper & Row Publishers.

Prothero, Donald R.; Interpreting the Stratigraphic Record; 1990, W.H. Freeman & Company.

Go To Page: 1 2 3

Articles in this Topic    Discussions in this Topic