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1. The movement caused within a fluid by the tendency of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity, which consequently results in the transfer of heat.

2. Mantle convection is the very slow creeping motion of Earth's solid silicate mantle caused by convection currents carrying heat from the interior to the planet's surface. The Earth's surface lithosphere rides atop the asthenosphere and the two form the components of the upper mantle.

3. Geologists have hypothesized that the movement of tectonic plates is related to convection currents in the earth's mantle. ... Tremendous heat and pressure within the earth cause the hot magma to flow in convection currents. These currents cause the movement of the tectonic plates that make up the earth's crust.

4.  Compare and contrast ridge pull and slab pull. ... Ridge push is a process in which the uplifted ridge is thought to push the oceanic plate toward the subduction zone. Slab pull is a process whereby the weight of a subducting plate helps to pull the trailing lithosphere into the subduction zone.

I used google. These are not my words.

the second type of galaxy is called a barred spiral, which has a thing called a bar straddling the nucleus

within 30 of the equator hope this