Seafloor Spreading Notes. Magnetic Reversal Notes. Magnetic Reversal Website. What do we mean by a magnetic reversal or a magnetic 'flip' of the Earth?
The Earth has a magnetic field, as can be seen by using a magnetic compass. It is mainly generated in the very hot molten core of the planet and has probably existed throughout most of the Earth's lifetime. The magnetic field is largely that of a dipole, by which we mean that it has one North pole and one South pole. At these places, a compass needle will point straight down, or up, respectively. Magnetic reversal picture. Magnetometer Notes. Magnetometer Website. Magnetometer, an instrument for measuring the strength and sometimes the direction of a magnetic field.
An important use of magnetometers is in measuring the earth's magnetic field. By detecting irregularities in the earth's magnetic field, a magnetometer can indicate the location of deposits of magnetic ore, such as iron ore, or of geological formations associated with petroleum. Magnetometer Picture. Mid-Ocean Ridge Notes. Mid-Ocean Ridge Website. A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics.
This uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary. The mid-ocean ridges of the world are connected and form a single global mid-oceanic ridge system that is part of every ocean, making the mid-oceanic ridge system the longest mountain range in the world, with a total length of about 60,000 km. There are two processes, ridge-push and slab-pull, thought to be responsible for the spreading seen at mid-ocean ridges, and there is some uncertainty as to which is dominant.
Ridge-push occurs when the weight of the ridge pushes the rest of the tectonic plate away from the ridge, often towards a subduction zone. Mid-Ocean Ridge Picture.