EESA06H3 Lecture Notes - Lecture 2: Basalt, San Andreas Fault, Gabbro
Document Summary
Sea floor created at mor"s recycled into mantle at trenches. Inclination: inclination of magnetic line of force within the earths magnetic field (changing depth/controls latitude) Declination: the orientation of anything with respect to magnetic north (has a declination of 0-360) Periodically the earth"s magnetic field flips, north magnetic pole changes to south. There are present orientation of earth"s magnetic field, there is also lava that flows, showing reverse magnetism. Magnetometer surveys of ocean floor identified patterns of anomalies on each side of mor"s. Magnetic reversals in lavas average every 500,000 years. Takes = 10,000 years or less for a reversal to occur. If we know the timing of the reversals, we can map and determine the age of the ocean floor. The factories where we produce the ocean floor. Crust produced in subduction zones (melts and creates new crust) The highs of the ocean floor mean that there is a positive magnetic anomaly.
