By Mayo Clinic Staff. Erectile dysfunction â the inability to get and keep an erection firm enough for sex â is a common problem. You've likely seen advertisements for erectile dysfunction herbs or supplements to increase your sexual performance..
plate tectonics. In geology, a theory that the Earth's lithosphere (crust and upper mantle) is divided into a number of large, plate-like sections that move as distinct masses. See Notes at fault, Gondwanaland, See more at tectonic boundary.
What is a tectonic plate? Tectonic plates are segments of the Earth's lithosphere, the hardrocky outer shell composed of the crust and the uppermost mantle.This shell is divided by lines of faults, ridâ¦ges of plate creation,and zones of plate destruction.