Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Paleomagnetism
Document related concepts
Friction-plate electromagnetic couplings wikipedia , lookup
Magnetosphere of Jupiter wikipedia , lookup
Maxwell's equations wikipedia , lookup
Van Allen radiation belt wikipedia , lookup
Magnetosphere of Saturn wikipedia , lookup
Geomagnetic storm wikipedia , lookup
Electromagnetism wikipedia , lookup
Superconducting magnet wikipedia , lookup
Mathematical descriptions of the electromagnetic field wikipedia , lookup
Edward Sabine wikipedia , lookup
Magnetic stripe card wikipedia , lookup
Lorentz force wikipedia , lookup
Neutron magnetic moment wikipedia , lookup
Giant magnetoresistance wikipedia , lookup
Magnetic monopole wikipedia , lookup
Magnetic nanoparticles wikipedia , lookup
Magnetometer wikipedia , lookup
Electromagnetic field wikipedia , lookup
Force between magnets wikipedia , lookup
Multiferroics wikipedia , lookup
Earth's magnetic field wikipedia , lookup
Electromagnet wikipedia , lookup
Magnetotactic bacteria wikipedia , lookup
Magnetochemistry wikipedia , lookup
Magnetotellurics wikipedia , lookup
Magnetoreception wikipedia , lookup
Geomagnetic reversal wikipedia , lookup
Transcript
Paleomagnetism Aging the Ocean Floor Paleomagnetism Paleomagnetism, or ‘ancient magnetism,’ is the study of the changes in Earth’s magnetic field over its history to determine how old the ocean floor is in a particular spot. Magnetic Field • Earth’s magnetic field originates in the core and it can reverse direction. – Currently the magnetic field originates in the north. • We don’t know why it reverses, or how to predict when it will occur. • The field has reversed about 20 times in the last 5 million years – the most recent was 730 000 years ago. • The oldest ocean floor is 200 MY, and is in the northwest Pacific. Oldest Ocean Crust Magnetic North • In the asthenosphere there is a mineral called magnetite, which emerges in lava at mid-oceanic ridges. • It is magnetic, and as the new crust hardens, its particles lock in place pointing in the direction of the origin of the magnetic field. • Since the particles will align in different directions depending on where the magnetic origin is, the result is an equal pattern on either side of a ridge showing how many times the field has shifted, and how long each shift lasted. • The further from the ridge the ocean floor is, the older it is. • The oldest ocean floor is in trenches. Detecting the Field • Earth’s magnetic field can’t be seen by the naked eye, and it also can’t be detected by a compass. • Instead, we use a device called a magnetometer which graphs out the changes in the magnetic field. • It is built into a ship or an airplane.
