The geology of the area changes through the years as rock units are deposited and added, and deformational processes change their shapes and locations. Deposition can happen when sediments settle onto the surface of the planet and later lithify into sedimentary rock, or when as volcanic substance like volcanic lava or ash flows blanket the surface. Igneous intrusions like batholiths, laccoliths, dikes, and sills, push upwards into the overlying rock, and crystallize as they intrude. After the first sequence of stones was deposited, the stone units could be deformed and/or metamorphosed. Deformation typically occurs as a consequence of horizontal shortening, horizontal extension, or side-to-side (strike-slip) motion. These structural regimes broadly relate to convergent boundaries, divergent boundaries, and change boundaries, respectively, involving tectonic plates.