atrial fibrillation. n. Abbr. AF. Fibrillation in which the normal rhythmical contractions of the cardiac atria are replaced by rapid irregular twitchings of the muscular wall that cause the ventricles to respond irregularly. Also called a-fib, auricular fibrillation.
continental=on land. here is a good example of plate tectonics, i just had to explain all that stuff. Subduction is when converging plates come together. they make a trench by one plate sliding under the other and into the mantle.
Tectonic plates never stop moving, this process is called continental drift. Tectonic plates move because of convection currents. These convection currents happen in the mantle, underneath the tectonic plates. The heat, which causes the convection currents, is produced from the radioactive decay left over from the Earths formation.