It's mean the theory that changes in the earth's crust during geological history have resulted from the action of continuous and uniform processes.
A substance that cant be broken down by cheamical or physical means is an Element.
Hope this helps
It's the weakest of all the intermolecular forces present in chemistry . the London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. This force is sometimes called an induced dipole-induced dipole attraction.
H........................................